Surface treatment process for an aluminium alloy profile

Abstract

The application discloses a surface treatment process of an aluminum alloy profile and belongs to the technical field of aluminum alloy processing. The aluminum alloy profile is immersed into an oil removal cleaning solution, and the pretreatment of the aluminum alloy profile is completed under the assistance of ultrasonic waves. The pretreated aluminum alloy profile is used as an anode, and anodic oxidation treatment is carried out under the assistance of ultrasonic waves and constant voltage. The anodic oxidation treatment is stopped when particles are generated in an electrolyte through a liquid particle counting system. The aluminum alloy profile after the anodic oxidation treatment and cleaning is used as a cathode to carry out electrophoretic treatment. Then, the cathode is taken out and washed with clean water for 3-5 times. After being dried at room temperature, the aluminum alloy profile is dried at 140 DEG C for 30 min, and the electrophoretic coating is completed. Fluorine atoms are introduced into the electrophoretic paint during preparation, which is helpful to increase the corrosion resistance and wear resistance of the paint film. The liquid particle counting system is used for monitoring during the anodic oxidation treatment, so that the anodic oxidation is prevented from being excessive, and the paint film with better adhesion and smoothness is formed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum alloy processing, and particularly relates to a surface treatment process of aluminum alloy profiles. BACKGROUND

[0002] Aluminum alloy is an alloy material taking aluminum as a base element and adding a certain amount of other metal elements, and is one of light metal materials. The aluminum alloy profile is the most widely used non-ferrous structural material in industrial production and is widely used in the fields of aerospace, aviation, automobile, machinery manufacturing, shipbuilding, building, decoration and the like.

[0003] Aluminum alloy has good corrosion resistance. The aluminum alloy is composed of aluminum and metal elements such as copper, manganese, nickel and titanium. When the aluminum alloy is exposed to an oxidizing environment, aluminum atoms will chemically react with oxygen to form a dense oxide film, thereby preventing further corrosion of the metal. However, the oxide film formed by self-oxidation is relatively thin and easy to remove. The corrosion potential of aluminum is negative, and when the aluminum alloy is in contact with other metals, galvanic corrosion problem is easy to occur. Therefore, the aluminum alloy needs to be surface treated during the processing process, so as to solve or improve its corrosion resistance and decorative function.

[0004] The corrosion resistance of the aluminum alloy is generally obtained by anodic oxidation treatment. After anodic oxidation, the oxide film of the aluminum alloy profile is easy to present a yellow tone, which covers the color of the aluminum alloy itself and is not beautiful enough. In addition, if the oxidation process is not properly controlled, a loose oxide film is easy to be generated, resulting in poor corrosion resistance. By coating anticorrosive paint, the adhesion between the paint and the aluminum alloy profile is also poor. Therefore, a surface treatment process of the aluminum alloy profile is proposed. SUMMARY

[0005] The purpose of the present application is to provide a surface treatment process of an aluminum alloy profile to solve the problems in the background art.

[0006] The purpose of the present application can be achieved by the following technical solutions.

[0007] A surface treatment process of an aluminum alloy profile comprises the following steps:

[0008] Step 1: immerse the aluminum alloy profile in an oil removal cleaning solution under the assistance of an ultrasonic wave with a power of 3-3.5 KW for 3-5 min, then rinse the aluminum alloy profile with clean water for 3-5 times to complete the pretreatment of the aluminum alloy profile.

[0009] The oil removal cleaning solution comprises sodium carbonate, sodium hydroxide, triethanolamine, sodium dodecyl benzene sulfonate and deionized water. The amount ratio of sodium carbonate, sodium hydroxide, triethanolamine, sodium dodecyl benzene sulfonate and deionized water is 2-3 g: 3 g: 1-1.5 g: 0.5-1 g: 40 g.

[0010] Step two: using a solution of sulfuric acid with a mass concentration of 150-170 g / L as electrolyte, electrolyte is introduced into the electrolytic cell, the pretreated aluminum alloy profile is immersed in the electrolyte, lead plate is used as cathode and aluminum alloy profile is used as anode, anodic oxidation treatment is carried out under the condition of 2.5-3 KW power ultrasonic wave assistance and 10-15 V constant voltage.

[0011] The temperature of electrolyte is kept at 15-20 ℃ during anodic oxidation treatment, and the electrolyte is stirred and circulated in the way of axial flow; during the anodic oxidation treatment, a detection sensor of liquid particle counting system is arranged below the anode in the electrolyte, and the liquid particle counting system is used to detect whether particles are generated in the electrolyte, and the anodic oxidation treatment is stopped when particles are detected.

[0012] Step three: the aluminum alloy profile after anodic oxidation treatment is washed with clean water for 3-5 times, and the electrophoretic paint is diluted with deionized water to form an electrophoretic solution with a solid content of 15-18%; cathode electrophoresis treatment is carried out under the condition of 100 V voltage for 2-3 min, then the cathode is taken out and washed with clean water for 3-5 times, and dried at 140 ℃ for 30 min after air drying at room temperature, to complete the electrophoretic coating and the surface treatment process of the aluminum alloy profile.

[0013] Further, the electrophoretic paint is prepared by the following steps:

[0014] Step 1: propylene glycol methyl ether and propylene glycol methyl ether acetate are stirred and mixed, heated to 90-95 ℃ under nitrogen protection, then dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, methyl methacrylate, styrene, hexafluorobutyl methacrylate and azobisisobutyronitrile are added, stirred and mixed, then heated for 4-5 h, then dibutyltin dilaurate and dibutylhydroxytoluene are added and uniformly mixed to obtain an acrylate copolymer supplement solution;

[0015] The amount ratio of propylene glycol methyl ether, propylene glycol methyl ether acetate, dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, methyl methacrylate, styrene, hexafluorobutyl methacrylate, azobisisobutyronitrile, dibutyltin dilaurate and dibutylhydroxytoluene is 50 g: 50 g: 28-30 g: 40 g: 60 g: 10 g: 15 g: 8 g: 0.05 g: 0.3 g.

[0016] Step 2: isophorone diisocyanate, dibutyltin dilaurate and dibutyltin hydroxytoluene are stirred and mixed, then hydroxyethyl methacrylate is added at 40-45 ℃, the conversion rate of isocyanate group is determined by toluene-dibutylamine titration method to reach 40%, then the acrylate copolymer supplement solution is added, and after complete reaction without isocyanate group, the temperature is lowered to 50 ℃, and lactic acid is used to adjust the pH value to 7 to obtain a polyacrylate resin.

[0017] The ratio of the supplementary solution containing isophorone diisocyanate, dibutyltin dilaurate, dibutyltin hydroxytoluene, hydroxyethyl methacrylate, and acrylate copolymer is 290g:0.03g:0.25g:170g:260g.

[0018] The beneficial effects of this invention are:

[0019] The surface treatment process for aluminum alloy profiles in this invention first removes grease from the surface of the aluminum alloy profiles using a low-concentration alkaline degreasing cleaning solution. Under ultrasonic assistance, saponified grease can be removed from the surface of the aluminum alloy profiles, which helps to increase the degreasing effect, completes degreasing in a shorter cleaning time, and prevents excessive corrosion of the aluminum alloy profiles. During the anodizing process, a liquid particle counting system is used for monitoring. Anodizing is stopped when alumina particles are detected, which helps to form a thicker oxide film while avoiding over-anodizing, thus preventing the formation of a loose oxide film. Fluorine atoms are introduced during the preparation of the electrophoretic paint, which helps to increase the corrosion resistance and wear resistance of the paint film. In the subsequent electrophoretic coating process, the electrophoretic paint can better penetrate into the pores of the oxide film, which helps to form a paint film with better adhesion and a smooth and flat surface, thereby improving the appearance performance of the aluminum alloy profiles. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] This embodiment prepares an electrophoretic paint, including the following steps: 3

[0023] Step 1: Mix 10 kg of propylene glycol methyl ether and 10 kg of propylene glycol methyl ether acetate, heat to 90°C under nitrogen protection, then add 5.6 kg of dimethylaminoethyl methacrylate, 8 kg of hydroxyethyl methacrylate, 12 kg of methyl methacrylate, 2 kg of styrene, 3 kg of hexafluorobutyl methacrylate and 1.6 kg of azobisisobutyronitrile, mix and keep warm for 4 hours, then add 10 g of dibutyltin dilaurate and 60 g of dibutylhydroxytoluene and mix evenly to obtain the acrylate copolymer replenishment solution.

[0024] Step 2: Mix 29 kg of isophorone diisocyanate, 3 g of dibutyltin dilaurate, and 25 g of dibutyltin hydroxytoluene. Then, add 17 kg of hydroxyethyl methacrylate at 40 °C. The conversion rate of isocyanate groups is determined to be 40% by toluene-di-n-butylamine titration. Then, add 26 kg of acrylate copolymer replenishing solution. After the reaction is complete and no isocyanate groups remain, cool to 50 °C and adjust the pH to 7 with lactic acid to obtain polyacrylate resin.

[0025] Example 2

[0026] This embodiment prepares an electrophoretic paint, including the following steps:

[0027] Step 1: Mix 10 kg of propylene glycol methyl ether and 10 kg of propylene glycol methyl ether acetate, and heat to 92°C under nitrogen protection. Then add 5.8 kg of dimethylaminoethyl methacrylate, 8 kg of hydroxyethyl methacrylate, 12 kg of methyl methacrylate, 2 kg of styrene, 3 kg of hexafluorobutyl methacrylate, and 1.6 kg of azobisisobutyronitrile. After mixing, keep the mixture at this temperature for 4.5 h. Then add 10 g of dibutyltin dilaurate and 60 g of dibutylhydroxytoluene and mix well to obtain the acrylate copolymer replenishment solution.

[0028] Step 2: Mix 29 kg of isophorone diisocyanate, 3 g of dibutyltin dilaurate, and 25 g of dibutyltin hydroxytoluene. Then, add 17 kg of hydroxyethyl methacrylate at 42 °C. The conversion rate of isocyanate groups is determined to be 40% by toluene-di-n-butylamine titration. Then, add 26 kg of acrylate copolymer replenishing solution. After the reaction is complete and no isocyanate groups remain, cool to 50 °C and adjust the pH to 7 with lactic acid to obtain polyacrylate resin.

[0029] Example 3

[0030] This embodiment prepares an electrophoretic paint, including the following steps:

[0031] Step 1: Mix 10 kg of propylene glycol methyl ether and 10 kg of propylene glycol methyl ether acetate, heat to 95°C under nitrogen protection, then add 6 kg of dimethylaminoethyl methacrylate, 8 kg of hydroxyethyl methacrylate, 12 kg of methyl methacrylate, 2 kg of styrene, 3 kg of hexafluorobutyl methacrylate and 1.6 kg of azobisisobutyronitrile, mix and keep warm for 5 hours, then add 10 g of dibutyltin dilaurate and 60 g of dibutylhydroxytoluene and mix evenly to obtain the acrylate copolymer replenishment solution.

[0032] Step 2: 29 kg of isophorone diisocyanate, 3 g of dibutyltin dilaurate, 25 g of dibutyltin hydroxytoluene were stirred and mixed, then 17 kg of hydroxyethyl methacrylate was added at 45°C, the conversion rate of isocyanate groups was determined by toluene-dibutylamine titration method to reach 40%, then 26 kg of acrylate copolymer supplement solution was added, and the reaction was completed until no isocyanate group was detected, then the temperature was lowered to 50°C, lactic acid was used to adjust the pH value to 7, and a polyacrylate resin was obtained.

[0033] Example 4

[0034] The present embodiment provides a surface treatment process for an aluminum alloy profile, comprising the following steps:

[0035] Step 1: Mix 200 kg of sodium carbonate, 300 kg of sodium hydroxide, 100 kg of triethanolamine, 50 kg of sodium dodecylbenzenesulfonate, and 4000 kg of deionized water to form an oil removal cleaning solution; immerse the aluminum alloy profile in the oil removal cleaning solution, and remove the oil under the assistance of a 3KW power ultrasonic wave for 3 minutes, then rinse the aluminum alloy profile with clean water for 3 times to complete the pretreatment of the aluminum alloy profile.

[0036] Step 2: Use a sulfuric acid solution with a mass concentration of 150 g / L as the electrolyte, and introduce the electrolyte into the electrolytic tank, immerse the pretreated aluminum alloy profile in the electrolyte, use a lead plate as the cathode and the aluminum alloy profile as the anode, and perform anodic oxidation treatment under the assistance of a 2.5KW power ultrasonic wave and a constant voltage of 10V; maintain the temperature of the electrolyte at 15°C during the anodic oxidation treatment, and use an axial flow method to stir and circulate the electrolyte; during the anodic oxidation treatment, set a detection sensor of a liquid particle counting system below the anode, and detect whether particles are generated in the electrolyte through the liquid particle counting system, and stop the anodic oxidation treatment when particles are detected.

[0037] Step 3: Rinse the aluminum alloy profile after anodic oxidation treatment with clean water for 3-5 times, dilute the electrophoretic paint prepared in Example 1 with deionized water to form an electrophoretic solution with a solid content of 15%; perform cathodic electrophoresis treatment at a voltage of 100V for 2 minutes with the aluminum alloy profile as the cathode, then take out the cathode and rinse it with clean water for 3 times, dry it at room temperature, and then dry it at 140°C for 30 minutes to complete the electrophoretic coating, and complete the surface treatment process of the aluminum alloy profile. According to GB / T 1720-2020, the adhesion of the electrophoretic coating film is 1 level, and the film is smooth and uniform.

[0038] Example 5

[0039] The present embodiment provides a surface treatment process for an aluminum alloy profile, comprising the following steps:

[0040] Step one: mix 200-300 kg of sodium carbonate, 300 kg of sodium hydroxide, 100-150 kg of triethanolamine, 80 kg of sodium dodecyl benzene sulfonate and 4000 kg of deionized water into a degreasing cleaning solution; immerse the aluminum alloy profile into the degreasing cleaning solution, and clean the oil under the assistance of ultrasonic wave with a power of 3.2 KW for 3-5 min, then rinse the aluminum alloy profile with clean water for 3-5 times to complete the pretreatment of the aluminum alloy profile.

[0041] Step two: use a sulfuric acid solution with a mass concentration of 160 g / L as electrolyte, and pass the electrolyte into the electrolytic tank, immerse the pretreated aluminum alloy profile into the electrolyte, use lead plate as cathode and aluminum alloy profile as anode, and perform anodic oxidation treatment under the assistance of ultrasonic wave with a power of 2.8 KW and a constant voltage of 12 V; keep the temperature of the electrolyte at 18 ℃ during the anodic oxidation treatment, and use the axial flow mode to stir and circulate the electrolyte; during the anodic oxidation treatment, set the detection sensor of the liquid particle counting system in the electrolyte below the anode, and detect whether particles are generated in the electrolyte through the liquid particle counting system, and stop the anodic oxidation treatment when particles are detected.

[0042] Step three: rinse the aluminum alloy profile after anodic oxidation treatment with clean water for 4 times, dilute the electrophoretic paint prepared in Example 2 with deionized water into an electrophoretic solution with a solid content of 16%; perform cathodic electrophoresis treatment under a voltage of 100 V with the aluminum alloy profile as cathode for 2.5 min, then take out the cathode and rinse it with clean water for 4 times, dry it at room temperature, and then dry it at 140 ℃ for 30 min to complete the electrophoretic coating, and complete the surface treatment process of the aluminum alloy profile. According to GB / T 1720-2020, the adhesion of the electrophoretic coating film is 1 level, and the film is smooth and uniform.

[0043] Example 6

[0044] The embodiment provides a surface treatment process of an aluminum alloy profile, which comprises the following steps:

[0045] Step one: mix 300 kg of sodium carbonate, 300 kg of sodium hydroxide, 150 kg of triethanolamine, 100 kg of sodium dodecyl benzene sulfonate and 4000 kg of deionized water into a degreasing cleaning solution; immerse the aluminum alloy profile into the degreasing cleaning solution, and clean the oil under the assistance of ultrasonic wave with a power of 3.5 KW for 5 min, then rinse the aluminum alloy profile with clean water for 5 times to complete the pretreatment of the aluminum alloy profile.

[0046] Step two: using a sulfuric acid solution with a mass concentration of 170 g / L as the electrolyte, the electrolyte is introduced into the electrolytic tank, the pretreated aluminum alloy profile is immersed in the electrolyte, the lead plate is used as the cathode and the aluminum alloy profile is used as the anode, and the anodic oxidation treatment is carried out under the condition of 3 KW power ultrasonic assistance and 15 V constant voltage; the temperature of the electrolyte is kept at 20 DEG C during the anodic oxidation treatment, and the electrolyte is stirred and circulated in the axial flow mode; during the anodic oxidation treatment, the detection sensor of the liquid particle counting system is arranged below the anode, and the liquid particle counting system is used to detect whether particles are generated in the electrolyte, and the anodic oxidation treatment is stopped when particles are detected.

[0047] Step three: the aluminum alloy profile after the anodic oxidation treatment is rinsed with clean water for 5 times, the electrophoretic paint prepared in Example 3 is diluted with deionized water to an electrophoretic liquid with a solid content of 18%; the aluminum alloy profile is used as the cathode to carry out cathode electrophoretic treatment under the condition of 100 V voltage for 3 min, then the cathode is taken out and rinsed with clean water for 5 times, and after air drying at room temperature, drying is carried out at 140 DEG C for 30 min, the electrophoretic coating is completed, and the surface treatment process of the aluminum alloy profile is completed. According to GB / T 1720-2020, the adhesion of the electrophoretic coating film is 1 level, and the film is smooth and uniform.

[0048] It should be noted that in this document, terms such as "comprise", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices including a series of elements not only include those elements, but also include other elements not explicitly listed, or inherent to such processes, methods, articles or devices.

[0049] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A surface treatment process for aluminum alloy profiles, characterized in that, Includes the following steps: Step 1: Immerse the aluminum alloy profile in the degreasing cleaning solution and clean it for 3-5 minutes with ultrasonic assistance at a power of 3-3.5KW. Then rinse the aluminum alloy profile with clean water 3-5 times to complete the pretreatment of the aluminum alloy profile. Step 2: Using the pretreated aluminum alloy profile as the anode, perform anodizing treatment with ultrasonic assistance at 2.5-3KW power and a constant voltage of 10-15V. Stop the anodizing treatment when particles are detected in the electrolyte by the liquid particle counting system. Step 3: Rinse the anodized aluminum alloy profile with clean water 3-5 times. Dilute the electrophoretic paint with deionized water to prepare an electrophoretic solution with a solid content of 15-18%. Use the aluminum alloy profile as the cathode and perform electrophoretic treatment at 100V for 2-3 minutes. Then remove the cathode and rinse it with clean water 3-5 times. After air drying at room temperature, dry it at 140℃ for 30 minutes to complete the electrophoretic coating and the surface treatment process of the aluminum alloy profile. The electrolyte is a sulfuric acid solution with a mass concentration of 150-170 g / L; The electrophoretic paint is prepared through the following steps: Isophorone diisocyanate, dibutyltin dilaurate, and dibutyltin hydroxytoluene were stirred and mixed. Then, hydroxyethyl methacrylate was added at 40-45°C. The conversion rate of isocyanate groups was determined to be 40% by toluene-di-n-butylamine titration. Then, acrylate copolymer replenishment solution was added. After the reaction was complete until no isocyanate groups were left, the temperature was lowered to 50°C, and the pH value was adjusted to 7 with lactic acid to obtain polyacrylate resin. The acrylate copolymer replenishment solution is prepared by the following steps: Propylene glycol methyl ether and propylene glycol methyl ether acetate were stirred and mixed, and then heated to 90-95℃ under nitrogen protection. Then, dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, methyl methacrylate, styrene, hexafluorobutyl methacrylate and azobisisobutyronitrile were added. After stirring and mixing, the mixture was kept at the temperature for 4-5 hours. Then, dibutyltin dilaurate and dibutylhydroxytoluene were added and mixed evenly to obtain the acrylate copolymer replenishment solution.

2. The surface treatment process for aluminum alloy profiles according to claim 1, characterized in that, The degreasing cleaning solution includes sodium carbonate, sodium hydroxide, triethanolamine, sodium dodecylbenzenesulfonate, and deionized water. The ratio of sodium carbonate, sodium hydroxide, triethanolamine, sodium dodecylbenzenesulfonate, and deionized water is 2-3g:3g:1-1.5g:0.5-1g:40g.

3. The surface treatment process for aluminum alloy profiles according to claim 1, characterized in that, The ratio of the supplementary solution containing isophorone diisocyanate, dibutyltin dilaurate, dibutyltin hydroxytoluene, hydroxyethyl methacrylate, and acrylate copolymer is 290g:0.03g:0.25g:170g:260g.

4. The surface treatment process for aluminum alloy profiles according to claim 1, characterized in that, The ratio of the following components is as follows: propylene glycol methyl ether, propylene glycol methyl ether acetate, dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, methyl methacrylate, styrene, hexafluorobutyl methacrylate, azobisisobutyronitrile, dibutyltin dilaurate, and dibutylhydroxytoluene.

5. The surface treatment process for aluminum alloy profiles according to claim 1, characterized in that, During the anodizing process, the electrolyte temperature is maintained at 15-20℃, and the electrolyte is stirred and circulated in an axial flow manner.