阅读说明：本技术 一种提高汽车多彩着色外饰件耐光老化性的方法 (Method for improving light aging resistance of automobile colorful coloring exterior trimming part ) 是由 别小卫 陈康东 王超 于 2021-08-13 设计创作，主要内容包括：本发明涉及一种提高汽车多彩着色外饰件耐光老化性的方法,属于铝合金表面处理技术领域。本发明公开了一种提高汽车多彩着色外饰件耐光老化性的方法,包括对铝合金制品进行超声波清洗、电化学抛光、阳极氧化、电化学扩孔、电解着色、电泳和固化；其中电化学扩孔为直流-交流-直流电化学扩孔,电解着色为直流-交流着色。电化学扩孔过程中先通第一次直流电,再通交流电,然后通第二次直流电,且第一次通直流电的电压与第二次通直流电的电压不同,第一次通直流电的时间与第二次通直流电的时间不同。(The invention relates to a method for improving the light aging resistance of automobile colorful coloring exterior trimming parts, belonging to the technical field of aluminum alloy surface treatment. The invention discloses a method for improving the light aging resistance of an automobile colorful coloring exterior trimming part, which comprises the steps of carrying out ultrasonic cleaning, electrochemical polishing, anodic oxidation, electrochemical reaming, electrolytic coloring, electrophoresis and curing on an aluminum alloy product; wherein the electrochemical pore expanding is direct current-alternating current-direct current electrochemical pore expanding, and the electrolytic coloring is direct current-alternating current coloring. The electrochemical reaming process is firstly conducted with direct current for the first time, then conducted with alternating current, and then conducted with direct current for the second time, the voltage of the direct current conducted for the first time is different from the voltage of the direct current conducted for the second time, and the time of the direct current conducted for the first time is different from the time of the direct current conducted for the second time.)

1. A method for improving the light aging resistance of colorful automobile coloring exterior trimming parts is characterized in that the preparation method comprises the steps of carrying out ultrasonic cleaning, electrochemical polishing, anodic oxidation, electrochemical pore expansion, electrolytic coloring, electrophoresis and solidification on an aluminum alloy product; the electrochemical pore expanding is direct current-alternating current-direct current electrochemical pore expanding, and the electrolytic coloring is direct current-alternating current coloring.

2. The method of claim 1, wherein the electrochemical reaming temperature is 10-20 ℃ and the total time is 3-13 min.

3. The method according to claim 1 or 2, wherein the electrochemical reaming process is performed by firstly applying direct current and then applying alternating current, and then applying direct current for the second time, wherein the effective voltage values of the direct current and the alternating current are 2-6V.

4. The method of claim 3, wherein the voltage of the first direct current is different from the voltage of the second direct current.

5. The method according to claim 1 or 2, wherein the time of the direct current is 1-4min, the time of the alternating current is 1-5min, and the time of the first direct current is different from the time of the second direct current.

6. The method according to claim 1, wherein the temperature of the electrolytic coloring is 16 to 20 ℃ and the total time is 5 to 10 min.

7. The method according to claim 1 or 6, wherein the electrolytic coloring is conducted by first conducting DC and then conducting AC, and the effective voltage value is 10-20V.

8. The method of claim 1, wherein the electrochemical polishing process is performed at a voltage of 25 to 35V, a temperature of 50 to 80 ℃, and a time of 15 to 25 min.

9. The method of claim 1, wherein the electrophoresis voltage is 80-120V, the temperature is 15-25 ℃, and the time is 1-4 min.

Technical Field

The invention belongs to the technical field of aluminum alloy surface treatment, and relates to a method for improving light aging resistance of automobile colorful coloring exterior trimming parts.

Background

Aluminum alloys are one of the ideal lightweight materials for automotive bodies due to their material properties, cost, and recyclability. With the application and development of aluminum alloy materials, surface treatment techniques are also rapidly developed. The main aluminum alloy surface treatment technology mainly comprises the following steps: anodic oxidation treatment, micro-arc oxidation, chemical oxidation treatment, coating, electroplating, enamel and the like, wherein the anodic oxidation treatment technology is developed most rapidly and has the most extensive application, thereby playing a very important role. The anodic oxidation electrolytic coloring of the aluminum alloy is one of the most widely applicable treatment methods in the surface treatment of the aluminum alloy, and a dense oxide film is formed on the surface of an aluminum piece by using the anodic oxidation method, so that the corrosion resistance, the hardness, the wear resistance and the decoration of the aluminum alloy are remarkably improved.

Although the processes of chemical coloring, primary electrolytic coloring, secondary electrolytic coloring, tertiary electrolytic coloring and the like have been developed in the current aluminum alloy coloring, the long-term corrosion resistance and light aging resistance of the aluminum alloy multicolor technology still remain the relatively troublesome problems faced at present. Especially the colorful durability of the automobile decoration in the field of automobile parts. Therefore, there is a need to develop a process for imparting high corrosion resistance, high durability and light aging resistance to the colored layer on the surface of the aluminum alloy.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a method for improving the light aging resistance of colorful coloring exterior trimming parts of automobiles.

The purpose of the invention can be realized by the following technical scheme:

a method for improving the light aging resistance of colorful automobile exterior trimming parts comprises the steps of ultrasonic cleaning, electrochemical polishing, anodic oxidation, electrochemical pore expansion, electrolytic coloring, electrophoresis and curing of an aluminum alloy product.

Preferably, the electrochemical pore expanding is direct current-alternating current-direct current electrochemical pore expanding, and the electrolytic coloring is direct current-alternating current coloring.

The electrochemical reaming and electrolytic coloring process is the key process steps of the invention, wherein the electrochemical reaming is firstly conducted with direct current and then alternating current, and the electrolytic coloring is firstly conducted with direct current and then alternating current. The voltage and the electrifying time of the direct current electrified for the first time, the direct current electrified for the second time and the alternating current electrified for the second time in the electrochemical reaming are not completely the same; the voltage of direct current and alternating current and the electrifying time are not completely the same in electrolytic coloring; and the voltage of the electrolytic coloration is higher than the electrochemical pore expansion. In addition, the electrochemical hole expanding process with different voltage and time is combined with the electrolytic coloring process with the same voltage and time, so that the surface of the material can present different colors.

Preferably, the temperature of the electrochemical reaming process is 10-25 ℃, and the total time is 3-13 min.

Further preferably, the electrochemical reaming process is performed in a sulfuric acid solution.

Preferably, the effective voltage values of both the direct current and the alternating current are 2 to 6V.

Further preferably, the voltage of the first direct current is different from the voltage of the second direct current.

Preferably, the time for electrifying the direct current is 1-4min, and the time for electrifying the alternating current is 1-5 min.

Further preferably, the time of the first direct current is different from the time of the second direct current.

Still more preferably, the time for applying the direct current is different from the time for applying the alternating current.

Preferably, the electrolytic coloring process comprises firstly applying DC and then applying AC, wherein the voltage is 10-20V, the temperature is 16-20 deg.C, and the total time is 5-10 min.

Further preferably, the voltage effective values of the direct current and the alternating current in the electrolytic coloring process are both 10 to 20V.

Still more preferably, the electrolytic coloring process is carried out in a solution containing a metal salt comprising: one or more of stannous sulfate, magnesium sulfate, nickel sulfate and zinc sulfate.

Electrolytic coloring is an important step affecting the color of products, and products obtained under different process parameters have different effects. The coloring uniformity is deteriorated due to the excessively high electrolytic coloring temperature; the over-voltage can cause the coloring speed to be reduced and even cause the film to fall off; too long a period of time can result in a dark surface.

Preferably, the ultrasonic cleaning solution is a weakly alkaline deoiling and deashing agent, the concentration is 40-60 g/L, the time is 8-20min, and the ultrasonic frequency is 30-50 KHz.

And selecting whether to perform an etching step or not according to different appearance requirements. If the etching is not carried out, the surface of the material presents a lustrous feeling; if etching is performed, the surface of the material presents a sandy feeling.

Preferably, the electrochemical polishing is carried out in a sulfuric acid/phosphoric acid double-acid solution with the phosphoric acid concentration of 700-900g/L and the sulfuric acid concentration of 300-500g/L, the voltage is 25-35V, the temperature is 50-80 ℃, and the time is 15-25 min.

And carrying out electrochemical polishing under the conditions to flatten the surface of the aluminum piece. Too long a time can result in a dark surface; too short a time may result in spotting. Too high a temperature can cause corrosion of the material; too low a temperature can result in shadowing of the material surface.

Preferably, the anodic oxidation is carried out in an oxidation tank containing an acidic solution at a temperature of 16-20 deg.C and a voltage of 15-20V for a period of 20-30 min.

The anodic oxidation process is carried out under the condition of direct current, and an oxide film is formed on the surface of the aluminum piece. The technological parameters of the anodic oxidation process are controlled, so that the generated oxide film has the characteristics of elasticity, porosity, corrosion resistance, wear resistance and the like, and the subsequent process is facilitated to be promoted.

Preferably, the electrophoresis voltage is 80-120V, the temperature is 15-25 ℃, and the time is 1-4 min.

Further preferably, the solid component in the solution in the electrophoresis tank comprises an electrophoresis refining resin, the conductivity is 600-800. mu.s/cm, and the pH value is 7.9-8.6.

Still more preferably, the electrophoretic refined resin comprises one or both of acrylic resin and melamine resin.

The electrophoresis process needs to control the parameter conditions of temperature, time, voltage, pH value and conductivity, so that the sealing process is effective and the color stability is ensured. Too short electrophoresis time can cause the paint film to be too thin and even not good in film forming; too long an electrophoresis time may result in uneven film thickness. Too high an electrophoretic voltage can cause paint film defects, roughness and even breakdown; too low an electrophoretic voltage may result in thinning of the paint film and decrease of the electrophoretic permeability. The electrophoresis temperature is too high, so that a paint film is rough and wrinkled, and the swimming transmittance and the adhesive force are poor; too low an electrophoresis temperature can lead to uneven paint films. Too high pH value and conductivity of the electrophoresis tank liquid can cause paint film to be coarse and block; too low a pH of the bath solution leads to no varnish.

Preferably, the curing process comprises the step of keeping the aluminum piece at the temperature of 160-200 ℃ for 30-60 min.

Compared with the prior art, the invention has the following beneficial effects:

1. electrochemical reaming is carried out through a direct current-alternating current-direct current alternating process, and then electrolytic coloring is carried out, so that the diversity and stability of the surface color of the aluminum piece are realized.

2. Compared with the traditional electrolytic coloring technology, the aluminum alloy piece subjected to direct current-alternating current-direct current reaming and electrophoresis sealing treatment can effectively maintain the stability of metal salt, improve the light aging resistance of the aluminum alloy piece, and greatly reduce the probability of stripping and fading of a product coating, thereby ensuring the performance of the aluminum alloy piece in use.

3. The treatment process for the colorful coloring surface of the aluminum alloy, provided by the invention, has the advantages of simple preparation method, convenience in operation, environmental protection, no pollution, good product effect, easiness in industrialization and wide application prospect.

Detailed Description

The following are specific examples of the present invention and further describe the technical solutions of the present invention, but the present invention is not limited to these examples. Unless otherwise specified, the raw materials used in the following examples of the present invention are all conventional raw materials, and the methods of use are all conventional methods.

The treated aluminum parts were tested according to the following method: and (3) suspending the sample in a photoaging test box, simulating natural conditions such as sunlight irradiation, high temperature, dew and the like, accelerating aging, and observing the surface of the sample.

Example 1

And (3) putting the aluminum piece into an ultrasonic cleaning machine, and ultrasonically cleaning for 9min under the action of a degreasing agent to remove attachments such as surface grease, dust and the like. And performing electrochemical polishing under a double-acid system, wherein the set voltage is 25V and the time is 17 min. And (3) carrying out oxidation treatment after the electrochemical polishing is finished, and adjusting the temperature of the oxidation tank to be 16 ℃, the electrifying time to be 20min and the electrifying voltage to be 15V. And (3) carrying out electrochemical reaming treatment on the oxidized aluminum piece in sulfuric acid, firstly introducing 3V direct current voltage for 2min, then introducing 4V alternating current voltage for 3min, and then introducing 5V direct current voltage for 2.5 min. And (3) carrying out electrolytic coloring treatment on the aluminum piece after hole expansion in an electrolyte containing stannous sulfate, and introducing 15V direct current at 18 ℃ and then 18V alternating current for coloring for 8 min. Then carrying out electrophoresis treatment, wherein the electrophoresis voltage is 80V, the temperature is 15 ℃, and the time is 2 min; and curing at 170 deg.C for 40 min.

Example 2

The difference compared to example 1 is that the electrochemical polishing was set at a voltage of 30V for a time of 25 min.

Example 3

Compared with the embodiment 1, the difference lies in that the temperature of the oxidation tank is adjusted to 18 ℃, the electrifying time is 30min, and the electrifying voltage is 18V during the anodic oxidation.

Example 4

Compared with the embodiment 1, the difference is that the direct current voltage of 5V is firstly applied, then the alternating current voltage of 3V is applied, and then the direct current voltage of 3V is applied during electrochemical hole expanding.

Example 5

Compared with the embodiment 1, the difference is that the direct current voltage of 4V is firstly applied, then the alternating current voltage of 6V is applied, and then the direct current voltage of 5V is applied during electrochemical hole expanding.

Example 6

The difference compared with example 1 is that the electrolytic coloring temperature is 20 ℃ and the time is 7 min.

Example 7

Compared with example 1, the difference is that the electrophoresis voltage is 80V, the temperature is 20 ℃, and the time is 3 min.

Example 8

The difference compared to example 1 is that the curing temperature is 190 ℃ and the time is 60 min.

Comparative example 1

The difference from example 1 is that 3V DC voltage was applied for 3min during the hole expanding treatment.

Comparative example 2

The difference from example 1 is that an AC voltage of 4V was applied for 3min during the hole expanding treatment.

Comparative example 3

The difference compared to example 1 is that no ultrasonic cleaning was performed.

Comparative example 4

Compared with example 1, the difference is that the electrochemical polishing voltage is 30V and the time is 40 min.

Comparative example 5

Compared with example 1, the difference is that the electrolytic coloring voltage is 8V and the time is 15 min.

Comparative example 6

Compared with example 1, the difference is that the electrophoresis voltage is 120V, the temperature is 5 ℃, and the time is 3 min.

The test results are shown in table 1:

TABLE 1 test results of samples after photoaging test

	Film thickness and gloss	Film falling out condition
			Example 1	The paint film is uniform and keeps luster	No shedding and foaming of paint film
Example 2	The paint film is uniform and keeps luster	A small part of the paint film falls off and foams
			Example 3	The paint film is uniform and keeps luster	No shedding and foaming of paint film
Example 4	The paint film is uniform and keeps luster	No shedding and foaming of paint film
			Example 5	The paint film is uniform and keeps luster	No shedding and foaming of paint film
Example 6	The paint film is uniform and keeps luster	No shedding and foaming of paint film
			Example 7	The paint film is uniform and has slightly dark color and luster	No shedding and foaming of paint film
Example 8	The paint film is uniform and keeps luster	No shedding and foaming of paint film
			Comparative example 1	The paint film is uniform and keeps luster	No shedding and foaming of paint film
Comparative example 2	The paint film is uniform and keeps luster	No shedding and foaming of paint film
			Comparative example 3	Even paint film and speckled surface	Partial falling off of paint film
Comparative example 4	Even paint film, gray surface color and slightly dark luster	No shedding phenomenon of paint film
			Comparative example 5	Even paint film, yellowish surface color and slightly dark luster	No shedding phenomenon of paint film
Comparative example 6	Uneven paint film, uneven surface color and luster	Partial falling off of paint film

The test result shows that: the paint films of the samples in examples 1-8 are uniform, almost free from discoloration, glossy, and free from obvious shedding and foaming phenomena; in the comparative examples, the thickness, color, gloss and light aging resistance of the paint film were all deficient due to process imperfections. And the examples 1, 4 and 5 can show different surface colors after the same electrolytic coloring process is carried out in the same solution.

In conclusion, the automobile colorful and colored exterior trimming part prepared by the ultrasonic cleaning, electrochemical polishing, anodic oxidation, electrochemical pore-enlarging, electrolytic coloring, electrophoresis and curing processes has good light aging resistance.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.