Powder type super-weather-resistant chromate-free aluminum alloy profile and preparation method thereof

Abstract

The invention relates to the technical field of powder coating preparation, provides a powder type super-weather-resistant chromate-free aluminum alloy profile and a preparation method thereof, and solves the problems that an existing powder coating for an aluminum alloy profile does not have high weather resistance, good compatibility and ecological environmental protection. Comprising the following steps: 1) oil removal treatment; (2) carrying out acid etching treatment; (3) chromate-free treatment; and (4) electrostatic spraying is conducted, specifically, super-weather-resistant powder coating is evenly sprayed to the surface of the aluminum alloy profile obtained through treatment in the step (S3) through an electrostatic spraying machine, then curing is conducted for 15-20 min at the temperature of 160-190 DEG C, the aluminum alloy profile is taken out and cooled, and the powder type super-weather-resistant chromate-free aluminum alloy profile is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of powder coating preparation, and in particular to a powder-type super-weather-resistant chromium-free aluminum alloy profile and a preparation method thereof. Background Art

[0002] Powder coatings have the characteristics of good decorativeness, environmental protection, high coating efficiency and excellent performance, and are widely used in aluminum profile coating. At present, the commercially available powder coatings for aluminum profiles are mainly polyester / TGIC system (TGIC is triglycidyl isocyanurate), and the film-forming substance of general polyester / TGIC system powder coatings is polyester resin. Ordinary aluminum profile ester resins can be divided into general industrial and building material grades according to the difference in weather resistance. The general industrial weather resistance is 3-4 years, and the building material grade weather resistance is 5-6 years.

[0003] Chinese patent application No. 202410324973.4 discloses a high-temperature-resistant and wear-resistant insulating thin spray coating and a preparation process thereof. The insulating thin spray coating is composed of the following components in parts by weight: 55-70 parts of polyurethane-epoxy resin, 20-40 parts of hyperbranched epoxy resin, 5-15 parts of curing agent, 8-12 parts of extinction barium, 20-25 parts of titanium dioxide, 1-3 parts of leveling agent, 0.7-0.9 parts of brightener, 0.2-0.4 parts of pure benzoin, 0.3-0.6 parts of PTFE-modified polyethylene wax, 0.5-0.7 parts of charge enhancer, 0-2 parts of pigment and 0.5-0.7 parts of aluminum oxide C; a preparation process of the thin spray coating is also provided. The thin spray coating provided by the invention has an adhesion of 0 level to the substrate and has excellent mechanical strength, flexibility, weather resistance, flame retardancy, corrosion resistance, friction resistance and impact resistance. It also has excellent insulation and high voltage resistance and can be used in battery tanks for new energy vehicles. However, the application still uses traditional triglycidyl isocyanurate as a curing agent, which is eco-toxic.

[0004] Chinese patent application No. 202311704011.3 discloses a process for preparing a polished heat-insulating aluminum profile, comprising the following steps: magnetic field homogenization treatment of aluminum alloy round cast rods; preliminary polishing and alkaline oxidation treatment of aluminum plates; preparation of heat-insulating adhesives; and coating of aluminum profiles. The invention uses an alkaline oxidation treatment solution prepared with sodium peroxide, sodium silicate, ammonium molybdate, sodium hydroxide, disodium ethylenediaminetetraacetic acid, sodium benzotriazole, polyethylene glycol 6000 and pure water to treat the clean aluminum plate, so that a uniform organic-inorganic metal oxide film is generated on the surface of the clean aluminum plate, which improves the bonding force between the aluminum profile and the powder coating in the subsequent coating process, so that more powder coating can be attached to the surface of the aluminum profile, making the coating layer with good heat-insulating properties more dense, and improving the heat-insulating capacity of the heat-insulating aluminum profile. The powder coating is prepared by mixing and grinding 0.03-0.04 parts by weight of azo pigment, 0.2-0.3 parts by weight of titanium dioxide, 0.4-0.5 parts by weight of hollow glass microspheres, 0.5-0.6 parts by weight of polyester resin and 0.3-0.4 parts by weight of lauryl alcohol acrylate into powder. The powder coating prepared by physically blending polyester resin with lauryl alcohol acrylate is prone to defects such as shrinkage cavitation and gloss loss, has poor compatibility between resins, and can only prepare medium and low gloss powder coatings. Summary of the invention

[0005] Therefore, in view of the above problems, the present invention provides a powder-type super-weather-resistant chromium-free aluminum alloy profile to solve the problem that the powder coatings used for existing aluminum alloy profiles do not have high weather resistance, good compatibility and ecological environmental protection.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A powder-type super-weather-resistant chromium-free aluminum alloy profile comprises the following raw materials: an aluminum alloy profile and a super-weather-resistant powder coating; wherein the preparation process of the super-weather-resistant powder coating is as follows:

[0008] I. Preparation of polyester resin: Add diol raw materials, dibasic acid raw materials and catalyst into a reaction kettle, introduce nitrogen, raise the temperature to 120-160°C, start stirring, continue to raise the temperature to 250-260°C, keep warm for 4-5h, and control the acid value to 4-12mgKOH / g;

[0009] II. Preparation of modified polyester resin: set the temperature to 220-240°C, add 80-200 parts by weight of modifier, react for 1-2h, add 50-100 parts by weight of KOH, adjust the acid value to 45-50mgKOH / g, keep warm for 2-4h, reduce the temperature to 200-210°C, adjust the vacuum degree to 0.09-0.10MPa, adjust the acid value to 30-35mgKOH / g, release the vacuum degree, cool to room temperature, and obtain modified polyester resin;

[0010] III. Preparation of super weather-resistant powder coating: Weigh 50-70 parts by weight of modified polyester resin, 1-3 parts by weight of calcium carbonate, 0.25-1 parts by weight of leveling agent, 0.25-0.75 parts by weight of coupling agent, and 0.25-0.75 parts by weight of benzoin, mix them evenly, add them to a high-speed pulverizer for pulverization, add them to a twin-screw extruder, mix and extrude, cool, crush, and sieve to obtain a super weather-resistant powder coating;

[0011] Wherein, the structural formula of the modifier is shown in formula (1):

[0012]

[0013] The R 1 For -F or The m is a positive integer.

[0014] Furthermore, the diol raw material includes: 250-270 parts by weight of neopentyl glycol, 5-8 parts by weight of trimethylolpropane, 50-60 parts by weight of cyclohexanedimethanol, and 20-25 parts by weight of ethyl butyl propanediol.

[0015] Furthermore, the dibasic acid raw materials include: 20-30 parts by weight of terephthalic acid, 2-6 parts by weight of trimellitic anhydride, 400-430 parts by weight of isophthalic acid, and 30-45 parts by weight of adipic acid.

[0016] Furthermore, the catalyst is monobutyltin oxide.

[0017] Furthermore, the temperature of the twin-screw extruder is set to 100-120° C., and the rotation speed is 30-45 r / min.

[0018] A method for preparing a powder-type super-weather-resistant chromium-free aluminum alloy profile comprises the following steps:

[0019] S1. Degreasing treatment: Treat in an acidic degreasing agent with a concentration of 1-3% for 1-3 minutes at a temperature of 20-25°C;

[0020] S2, acid etching treatment: add 1-10 parts by weight of ammonium bifluoride to a 10-20% sulfuric acid solution, stir and mix evenly to obtain an acid etching mixture, and then immerse the aluminum alloy profile in the acid etching mixture at a temperature of 20-25° C. for 1-3 minutes;

[0021] S3, chromium-free treatment: adjusting the pH of the chromium-free treatment solution to 2.0-3.0 and the temperature to 20-25° C., then immersing the aluminum alloy profile treated in step S2 in the chromium-free treatment solution for 1-2 minutes, and then drying for standby use;

[0022] S4, electrostatic spraying: use an electrostatic sprayer to evenly spray the super weather-resistant powder coating on the surface of the aluminum alloy profile obtained in step S3, and then cure it at 160-190° C. for 15-20 minutes, take it out and cool it to obtain a powder-type super weather-resistant chromium-free aluminum alloy profile.

[0023] Furthermore, the jet pressure of the electrostatic sprayer is 0.4-0.6 MPa, and the spraying thickness is controlled to be 60-70 microns.

[0024] Furthermore, the acidic degreasing agent is ZHM1206 acidic degreasing agent.

[0025] Furthermore, the chromium-free treatment solution is a mixed solution of Chemetall 4500 with a concentration of 1-3%.

[0026] By adopting the above technical solution, the beneficial effects of the present invention are:

[0027] 1. The modifier containing a large number of fluoroalkyl groups is a fluorine-containing polymer, which has the characteristics of high weather resistance, high heat resistance, high stability, and oil and water repellency. The carbon-fluorine bond (CF) has a strong polarity, and the bond energy of this bond is much higher than the general carbon-hydrogen bond (CH bond). Its shared electron pair is largely biased towards the fluorine atom, forming a layer of negative charge, which makes the main chain skeleton of the modifier's molecule very stable. This stability helps the fluorine-containing polymer resist the erosion of the external environment, thereby showing high weather resistance.

[0028] 2. The traditional curing agent triglycidyl isocyanurate (TGIC) has great eco-toxicity and has been included in the production capacity elimination catalog by the Ministry of Industry and Information Technology. The modifier used in this application can not only make the powder coating have super weather resistance, but also can be used as a curing agent to replace TGIC, which is more ecological and environmentally friendly. The polyester resin undergoes a ring-opening addition reaction with the epoxy group of the modifier through its terminal carboxyl group to form a network macromolecular structure containing an ester group. The molecular structure is compact and the cross-linking density is high, which helps to improve the impact resistance of the super weather-resistant powder coating. The higher cross-linking density can slow down the swelling of the super weather-resistant powder coating and has excellent aging resistance. The use of chemical grafting to graft the modifier onto the polyester resin can effectively solve the problem of compatibility between resins and improve the weather resistance of the polyester resin.

[0029] 3. Use an electrostatic sprayer to evenly spray the super weather-resistant powder coating on the surface of the aluminum alloy profile. The powder particles of the super weather-resistant powder coating adhere to the aluminum profile to form a uniform film. The excess powder is recycled through the recycling system, which has high efficiency, good economic benefits and is also environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the organic synthesis process of the modifier described in Example 1 of the present invention;

[0031] Figure 2 The curing mechanism of the reaction between the modifier and the polyester resin described in Example 1 of the present invention;

[0032] Figure 3 This is the organic synthesis process of the modifier described in Example 2 of the present invention;

[0033] Figure 4 This is the curing mechanism of the reaction between the modifier and the polyester resin described in Example 2 of the present invention. DETAILED DESCRIPTION

[0034] Example 1

[0035] A powder-type super-weather-resistant chromium-free aluminum alloy profile comprises the following raw materials: an aluminum alloy profile and a super-weather-resistant powder coating; wherein the preparation process of the super-weather-resistant powder coating is as follows:

[0036] I. Preparation of polyester resin: Add diol raw materials, dibasic acid raw materials and catalyst into a reaction kettle, introduce nitrogen, raise the temperature to 120°C, start stirring, continue to raise the temperature to 250°C, keep warm for 4 hours, and control the acid value to 4 mgKOH / g;

[0037] The diol raw materials include: 250 parts by weight of neopentyl glycol, 5 parts by weight of trimethylolpropane, 50 parts by weight of cyclohexanedimethanol, and 20 parts by weight of ethylbutylpropylene glycol; the dibasic acid raw materials include: 20 parts by weight of terephthalic acid, 2 parts by weight of trimellitic anhydride, 400 parts by weight of isophthalic acid, and 30 parts by weight of adipic acid; the catalyst is monobutyltin oxide;

[0038] II. Preparation of modified polyester resin: set the temperature to 220° C., add 80 parts by weight of modifier, react for 1 hour, add 50 parts by weight of KOH, adjust the acid value to 45 mgKOH / g, keep warm for 2 hours, reduce the temperature to 200° C., adjust the vacuum degree to 0.09 MPa, adjust the acid value to 30 mgKOH / g, release the vacuum degree, cool to room temperature, and obtain modified polyester resin;

[0039] III. Preparation of super weather-resistant powder coating: Weigh 50 parts by weight of modified polyester resin, 1 part by weight of calcium carbonate, 0.25 parts by weight of leveling agent, 0.25 parts by weight of coupling agent, and 0.25 parts by weight of benzoin, mix them evenly, add them to a high-speed grinder for grinding, and then add them to a twin-screw extruder. The temperature is set to 100° C. and the speed is 30 r / min. Mix and extrude, cool, crush, and sieve to obtain a super weather-resistant powder coating;

[0040] Wherein, the structural formula of the modifier is shown in formula (2):

[0041]

[0042] In formula (2), m is a positive integer; the organic synthesis process of the modifier is as follows Figure 1 As shown in Figure 2, the curing mechanism is as follows: Figure 2 As shown; the preparation process of the modifier is:

[0043] According to the weight ratio of double-ended perfluoropolyether alcohol and epichlorohydrin of 1:1, the double-ended perfluoropolyether alcohol and epichlorohydrin are mixed, the temperature is raised to 90°C, and then 0.3 parts by weight of tetramethylammonium bromide are added, the temperature is raised to 120°C, and the reaction is carried out for 6 hours. The temperature is lowered to room temperature, 0.3 parts by weight of 3% NaOH solution is added, and the mixture is stirred for 1 hour to obtain a crude product. The crude product is washed with distilled water, and the modifier is obtained after distillation and decompression.

[0044] The method for preparing the powder-type super-weather-resistant chromium-free aluminum alloy profile described above comprises the following steps:

[0045] S1. Degreasing treatment: Treat in 1% ZHM1206 acidic degreasing agent for 1 min at 20°C;

[0046] S2, acid etching treatment: add 1 part by weight of ammonium bifluoride to a 10% sulfuric acid solution, stir and mix evenly to obtain an acid etching mixed solution, and then immerse the aluminum alloy profile in the acid etching mixed solution at a temperature of 20° C. for 1 min;

[0047] S3, chromium-free treatment: adjusting the pH of the chromium-free treatment solution to 2.0, the chromium-free treatment solution is a 1% Chemetall 4500 mixed solution at a temperature of 20° C., and then immersing the aluminum alloy profile treated in step S2 in the chromium-free treatment solution for 1 min, and then drying for standby use;

[0048] S4, electrostatic spraying: use an electrostatic sprayer to evenly spray the super weather-resistant powder coating on the surface of the aluminum alloy profile obtained in step S3, the jet pressure of the electrostatic sprayer is 0.4MPa, and the spraying thickness is controlled to be 60 microns, and then cured at 160°C for 15 minutes, taken out and cooled, to obtain a powder-type super weather-resistant chromium-free aluminum alloy profile.

[0049] Example 2

[0050] A powder-type super-weather-resistant chromium-free aluminum alloy profile comprises the following raw materials: an aluminum alloy profile and a super-weather-resistant powder coating; wherein the preparation process of the super-weather-resistant powder coating is as follows:

[0051] II. Preparation of polyester resin: Add diol raw materials, dibasic acid raw materials and catalyst into a reaction kettle, introduce nitrogen, raise the temperature to 140°C, start stirring, continue to raise the temperature to 255°C, keep warm for 4.5 hours, and control the acid value to 8mgKOH / g;

[0052] The diol raw materials include: 260 parts by weight of neopentyl glycol, 6 parts by weight of trimethylolpropane, 55 parts by weight of cyclohexanedimethanol, and 22 parts by weight of ethylbutylpropylene glycol; the dibasic acid raw materials include: 25 parts by weight of terephthalic acid, 4 parts by weight of trimellitic anhydride, 410 parts by weight of isophthalic acid, and 35 parts by weight of adipic acid; the catalyst is monobutyltin oxide;

[0053] II. Preparation of modified polyester resin: set the temperature to 230° C., add 120 parts by weight of modifier, react for 1.5 hours, add 80 parts by weight of KOH, adjust the acid value to 48 mgKOH / g, keep warm for 3 hours, reduce the temperature to 205° C., adjust the vacuum degree to 0.095 MPa, adjust the acid value to 32 mgKOH / g, release the vacuum degree, cool to room temperature, and obtain modified polyester resin;

[0054] III. Preparation of super weather-resistant powder coating: Weigh 60 parts by weight of modified polyester resin, 2 parts by weight of calcium carbonate, 0.5 parts by weight of leveling agent, 0.5 parts by weight of coupling agent, and 0.5 parts by weight of benzoin, mix them evenly, add them to a high-speed grinder for grinding, and then add them to a twin-screw extruder. The temperature is set to 110° C. and the speed is 35 r / min. Mix and extrude, cool, crush, and sieve to obtain a super weather-resistant powder coating;

[0055] Wherein, the structural formula of the modifier is shown in formula (3):

[0056]

[0057] In formula (3), m is a positive integer; the organic synthesis process of the modifier is as follows Figure 3 As shown in Figure 2, the curing mechanism is as follows: Figure 4 As shown; the preparation process of the modifier is:

[0058] According to the weight ratio of single-ended perfluoropolyether alcohol and epichlorohydrin of 1:0.1, the single-ended perfluoropolyether alcohol and epichlorohydrin are mixed, the temperature is raised to 90°C, and then 0.3 parts by weight of tetramethylammonium bromide are added, the temperature is raised to 120°C, the reaction is carried out for 8 hours, the temperature is lowered to room temperature, 0.03 parts by weight of 3% NaOH solution is added, and the mixture is stirred for 1 hour to obtain a crude product, the crude product is washed with distilled water, and the modifier is obtained after distillation and decompression.

[0059] The method for preparing the powder-type super-weather-resistant chromium-free aluminum alloy profile described above comprises the following steps:

[0060] S1. Degreasing treatment: Treat in 2% ZHM1206 acidic degreasing agent for 2 minutes at a temperature of 2°C;

[0061] S2, acid etching treatment: add 5 parts by weight of ammonium bifluoride to a 15% sulfuric acid solution, stir and mix evenly to obtain an acid etching mixture, and then immerse the aluminum alloy profile in the acid etching mixture at a temperature of 22° C. for 2 minutes;

[0062] S3, chromium-free treatment: adjust the pH of the chromium-free treatment solution to 2.5, the chromium-free treatment solution is a 2% Chemetall 4500 mixed solution at a temperature of 22° C., and then immerse the aluminum alloy profile treated in step S2 in the chromium-free treatment solution for 1.5 minutes, and then dry it for standby use;

[0063] S4, electrostatic spraying: use an electrostatic sprayer to evenly spray the super weather-resistant powder coating on the surface of the aluminum alloy profile obtained in step S3, the jet pressure of the electrostatic sprayer is 0.5MPa, and the spraying thickness is controlled to be 65 microns, and then cured at 170°C for 18 minutes, taken out and cooled, to obtain a powder-type super weather-resistant chromium-free aluminum alloy profile.

[0064] Example 3

[0065] A powder-type super-weather-resistant chromium-free aluminum alloy profile comprises the following raw materials: an aluminum alloy profile and a super-weather-resistant powder coating; wherein the preparation process of the super-weather-resistant powder coating is as follows:

[0066] III. Preparation of polyester resin: Add diol raw materials, dibasic acid raw materials and catalyst into a reaction kettle, introduce nitrogen, raise the temperature to 160°C, start stirring, continue to raise the temperature to 260°C, keep warm for 5 hours, and control the acid value to 12 mgKOH / g;

[0067] The diol raw materials include: 270 parts by weight of neopentyl glycol, 8 parts by weight of trimethylolpropane, 60 parts by weight of cyclohexanedimethanol, and 25 parts by weight of ethylbutylpropylene glycol; the dibasic acid raw materials include: 30 parts by weight of terephthalic acid, 6 parts by weight of trimellitic anhydride, 430 parts by weight of isophthalic acid, and 45 parts by weight of adipic acid; the catalyst is monobutyltin oxide;

[0068] II. Preparation of modified polyester resin: set the temperature to 240° C., add 200 parts by weight of modifier, react for 2 h, add 100 parts by weight of KOH, adjust the acid value to 50 mgKOH / g, keep warm for 4 h, reduce the temperature to 210° C., adjust the vacuum degree to 0.10 MPa, adjust the acid value to 35 mgKOH / g, release the vacuum degree, cool to room temperature, and obtain modified polyester resin;

[0069] III. Preparation of super weather-resistant powder coating: Weigh 70 parts by weight of modified polyester resin, 3 parts by weight of calcium carbonate, 1 part by weight of leveling agent, 0.75 parts by weight of coupling agent, and 0.75 parts by weight of benzoin, mix them evenly, add them to a high-speed pulverizer for pulverization, and then add them to a twin-screw extruder. The temperature is set to 120° C. and the speed is 45 r / min. Mix and extrude, cool, crush, and sieve to obtain a super weather-resistant powder coating;

[0070] Wherein, the modifier is the same as that in Example 1.

[0071] The method for preparing the powder-type super-weather-resistant chromium-free aluminum alloy profile described above comprises the following steps:

[0072] S1. Degreasing treatment: Treat in 3% ZHM1206 acidic degreasing agent for 3 minutes at a temperature of 25°C;

[0073] S2, acid etching treatment: add 10 parts by weight of ammonium bifluoride to a 20% sulfuric acid solution, stir and mix evenly to obtain an acid etching mixture, and then immerse the aluminum alloy profile in the acid etching mixture at a temperature of 25° C. for 3 minutes;

[0074] S3, chromium-free treatment: adjust the pH of the chromium-free treatment solution to 3.0, the chromium-free treatment solution is a 3% Chemetall 4500 mixed solution at a temperature of 25° C., and then immerse the aluminum alloy profile treated in step S2 in the chromium-free treatment solution for 2 minutes, and then dry it for standby use;

[0075] S4, electrostatic spraying: use an electrostatic sprayer to evenly spray the super weather-resistant powder coating on the surface of the aluminum alloy profile obtained in step S3, the jet pressure of the electrostatic sprayer is 0.6MPa, and the spraying thickness is controlled to be 70 microns, and then cured at 190°C for 20 minutes, taken out and cooled, to obtain a powder-type super weather-resistant chromium-free aluminum alloy profile.

[0076] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A powder-type super-weather-resistant chromium-free aluminum alloy profile, characterized in that: The invention comprises the following raw materials: aluminum alloy profiles and super weather-resistant powder coatings; wherein the preparation process of the super weather-resistant powder coatings is as follows: I. Preparation of polyester resin: Add diol raw materials, dibasic acid raw materials and catalyst into a reaction kettle, introduce nitrogen, raise the temperature to 120-160°C, start stirring, continue to raise the temperature to 250-260°C, keep warm for 4-5h, and control the acid value to 4-12mgKOH / g; II. Preparation of modified polyester resin: set the temperature to 220-240°C, add 80-200 parts by weight of modifier, react for 1-2h, add 50-100 parts by weight of KOH, adjust the acid value to 45-50mgKOH / g, keep warm for 2-4h, reduce the temperature to 200-210°C, adjust the vacuum degree to 0.09-0.10MPa, adjust the acid value to 30-35mgKOH / g, release the vacuum degree, cool to room temperature, and obtain modified polyester resin; III. Preparation of super weather-resistant powder coating: Weigh 50-70 parts by weight of modified polyester resin, 1-3 parts by weight of calcium carbonate, 0.25-1 parts by weight of leveling agent, 0.25-0.75 parts by weight of coupling agent, and 0.25-0.75 parts by weight of benzoin, mix them evenly, add them to a high-speed pulverizer for pulverization, add them to a twin-screw extruder, mix and extrude, cool, crush, and sieve to obtain a super weather-resistant powder coating; Wherein, the structural formula of the modifier is shown in formula (1): The R1 is -F or The m is a positive integer.

2. The powder-type super-weather-resistant chromium-free aluminum alloy profile according to claim 1, characterized in that: The diol raw material comprises: 250-270 parts by weight of neopentyl glycol, 5-8 parts by weight of trimethylolpropane, 50-60 parts by weight of cyclohexanedimethanol, and 20-25 parts by weight of ethyl butyl propanediol.

3. The powder-type super-weather-resistant chromium-free aluminum alloy profile according to claim 1, characterized in that: The dibasic acid raw materials include: 20-30 parts by weight of terephthalic acid, 2-6 parts by weight of trimellitic anhydride, 400-430 parts by weight of isophthalic acid, and 30-45 parts by weight of adipic acid.

4. The powder-type super-weather-resistant chromium-free aluminum alloy profile according to claim 1, characterized in that: The catalyst is monobutyltin oxide.

5. The powder-type super-weather-resistant chromium-free aluminum alloy profile according to claim 1, characterized in that: The temperature of the twin-screw extruder is set at 100-120°C and the rotation speed is 30-45r / min.

6. The method for preparing a powder-type super-weather-resistant chromium-free aluminum alloy profile according to claim 1, characterized in that: The following steps are involved: S1. Degreasing treatment: treat in an acidic degreasing agent with a concentration of 1-3% for 1-3 minutes at a temperature of 20-25°C; S2, acid etching treatment: add 1-10 parts by weight of ammonium bifluoride to a 10-20% sulfuric acid solution, stir and mix evenly to obtain an acid etching mixture, and then immerse the aluminum alloy profile in the acid etching mixture at a temperature of 20-25° C. for 1-3 minutes; S3, chromium-free treatment: adjusting the pH of the chromium-free treatment solution to 2.0-3.0 and the temperature to 20-25° C., then immersing the aluminum alloy profile treated in step S2 in the chromium-free treatment solution for 1-2 minutes, and then drying for standby use; S4, electrostatic spraying: use an electrostatic sprayer to evenly spray the super weather-resistant powder coating on the surface of the aluminum alloy profile obtained in step S3, and then cure it at 160-190° C. for 15-20 minutes, take it out and cool it to obtain a powder-type super weather-resistant chromium-free aluminum alloy profile.

7. The method for preparing a powder-type super-weather-resistant chromium-free aluminum alloy profile according to claim 6, characterized in that: The jet pressure of the electrostatic sprayer is 0.4-0.6MPa, and the thickness of the spraying is controlled to be 60-70 microns.

8. The method for preparing a powder-type super-weather-resistant chromium-free aluminum alloy profile according to claim 6, characterized in that: The acidic degreasing agent is ZHM1206 acidic degreasing agent.

9. The method for preparing a powder-type super-weather-resistant chromium-free aluminum alloy profile according to claim 6, characterized in that: The chromium-free treatment solution is a mixed solution of Chemetall 4500 with a concentration of 1-3%.

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