Corrosion-resistant aluminum profile protective film and preparation method thereof

Abstract

The invention relates to the technical field of metal material protection, and provides a corrosion-resistant aluminum profile protective film and a preparation method thereof. The corrosion-resistant aluminum profile protective film is prepared from the following raw materials in parts by weight: 60 to 80 parts of polyvinylidene fluoride, 20 to 30 parts of polytetrafluoroethylene micro powder, 15 to 25 parts of epoxy resin, 5 to 8 parts of modified boron nitride nanosheets, 3 to 5 parts of a silane coupling agent KH-550, 3 to 5 parts of an aluminum oxide-silicon dioxide compound, 8 to 12 parts of a composite toughening agent, 1 to 2 parts of an anti-ultraviolet agent and 0.5 to 1.5 parts of an antioxidant. The adhesive force, the salt mist resistance, the acid and alkali resistance and the mechanical property of the prepared protective film are all improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material protection, and specifically, to a corrosion-resistant aluminum profile protective film and a preparation method thereof. Background Art

[0002] Due to its light weight, high strength, easy processing and other characteristics, aluminum profiles are widely used in building curtain walls, transportation, electronic equipment, aerospace and other fields. However, in an environment with marine climate, industrial pollution or frequent acid rain, the surface of aluminum materials is prone to undergo electrochemical reactions with corrosive media such as Cl - , SO 4 2- and other corrosive media, resulting in problems such as pitting corrosion and intergranular corrosion.

[0003] Commercially available aluminum profile protective films are mainly based on polymer materials such as polyvinyl chloride (PVC), polyethylene (PE) and polyester (PET). Among them, PVC occupies the main market due to its low cost and good processability, but it has defects; PVC has high hardness and poor toughness, and is prone to crack due to external force impact during transportation or installation, and its brittleness increases in low-temperature environments. In addition, the C-Cl bond in the PVC molecule is prone to hydrolysis in acidic and alkaline environments, resulting in film layer powdering. To improve the above problems, the industry has tried to introduce nano-fillers for modification, but nano-particles are prone to agglomerate in the matrix, forming stress concentration points, and the compatibility between inorganic fillers and organic matrices is insufficient, resulting in interfacial debonding.

[0004] Therefore, the existing aluminum profile protective films have significant short boards in terms of mechanical strength, environmental aging resistance and environmental friendliness. In view of the above problems, the present invention proposes a new type of corrosion-resistant aluminum profile protective film and a preparation method thereof. Summary of the Invention

[0005] The present invention proposes a corrosion-resistant aluminum profile protective film and a preparation method thereof, which improve the adhesion, salt spray resistance, acid and alkali resistance and mechanical properties of the corrosion-resistant aluminum profile protective film.

[0006] The technical solution of the present invention is as follows: In the first aspect, the present invention proposes a corrosion-resistant aluminum profile protective film, which is composed of the following raw materials in parts by weight: 60-80 parts of polyvinylidene fluoride, 20-30 parts of polytetrafluoroethylene micropowder, 15-25 parts of epoxy resin, 5-8 parts of modified boron nitride nanosheets, 3-5 parts of silane coupling agent KH-550, 3-5 parts of alumina@silica composite, 8-12 parts of composite toughening agent, 1-2 parts of ultraviolet absorber, and 0.5-1.5 parts of antioxidant.

[0007] As a further technical solution, the polyvinylidene fluoride has a weight average molecular weight Mw of 500,000-600,000 and a melting point of 160-170°C.

[0008] As a further technical solution, the particle size of the polytetrafluoroethylene micropowder is 1-5 μm, reducing the surface energy to improve the stain resistance; As a further technical solution, the epoxy resin is bisphenol A type epoxy E-44, which can enhance the adhesion to the aluminum matrix. And the silane coupling agent KH-550 in the raw materials acts as a bridging molecule. One end of the silane coupling agent can react with the hydroxyl groups on the surface of inorganic materials (such as aluminum), and the other end can react with organic polymers, thereby enhancing the interfacial bonding force between the polymer and the aluminum matrix.

[0009] As a further technical solution, the preparation method of the modified boron nitride nanosheets includes: dispersing boron nitride nanosheets in absolute ethanol, adding 3-aminopropyltriethoxysilane, and performing ultrasonic treatment at 60-70 °C for 2-3 hours, and obtaining amino-functionalized modified boron nitride nanosheets after centrifugation and drying.

[0010] As a further technical solution, the thickness of the boron nitride nanosheets is 10-50 nm, and the lateral dimension is 1-5 μm. After being modified with amino silane, an oriented barrier layer is formed.

[0011] As a further technical solution, the dosage ratio of the boron nitride nanosheets, absolute ethanol and 3-aminopropyltriethoxysilane is 1-2 g: 200-220 mL: 4-6 mL.

[0012] As a further technical solution, the preparation method of the alumina@silica composite includes: stirring and mixing ethanol, deionized water and acetic acid, then adding the silane coupling agent KH560, stirring at 200-300 rpm for 25-35 min to obtain a silane coupling agent solution, adding the dried and pretreated nano powder to it, and performing ultrasonic treatment at 50-60 °C for 120-140 min. During the ultrasonic treatment, manually stir every 20 min to prevent particle sedimentation. After centrifugal separation and ethanol washing, it is dried at 60-80 °C to obtain.

[0013] As a further technical solution, the preparation method of the pretreated nano powder includes: mixing nano alumina and nano silica with a weight ratio of 3:1 evenly, and drying at 60-80 °C for 100-120 min to obtain the pretreated nano powder.

[0014] As a further technical solution, the dosage ratio of ethanol, deionized water, acetic acid, pretreated nano powder, ethanol and the silane coupling agent KH560 is 180-200 mL: 8-10 mL: 0.1-0.2 mL: 9-11 g: 0.3-0.4 g.

[0015] As a further technical solution, the composite toughening agent includes polyethersulfone and maleic anhydride grafted polyethylene with a weight ratio of 2-3:1.

[0016] As a further technical solution, the ultraviolet absorber is UV-9, and the antioxidant is antioxidant 1010.

[0017] In a second aspect, the present invention provides a method for preparing a corrosion-resistant aluminum profile protective film, the steps including: (1) Premixing: Mix polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene micropowder, and alumina@silica composite in a high-speed mixer at 85-95°C for 15-25 minutes, with a rotation speed of 1000-1200 rpm; (2) Modification: Add silane coupling agent KH-550 and modified boron nitride nanosheets, and continue mixing for 10-20 minutes; (3) Kneading: Add a composite toughening agent, an ultraviolet absorber, and an antioxidant, and knead in a kneader at 60-80 rpm; (4) Calendering: Calender into a film at 180-190°C through a two-roll calender, with a linear speed of 5-7 m / min; (5) Post-treatment: Cool to room temperature to obtain a protective film with a thickness of 0.2-0.4 mm.

[0018] As a further technical solution, the kneading temperature is 170-180°C, and the kneading time is 12-14 minutes.

[0019] The working principle and beneficial effects of the present invention are as follows: The present invention provides a technical solution for a corrosion-resistant protective film based on a multi-scale synergistic reinforcement mechanism. By optimizing the composite toughening agent ratio (polyethersulfone and maleic anhydride-grafted polyethylene), designing the synergistic barrier structure of modified boron nitride nanosheets and alumina@silica composite, and regulating the alumina / silica ratio inside the composite, the adhesion, salt spray resistance, chemical corrosion resistance, and mechanical properties of the protective film are comprehensively improved. Experiments show that: the adhesion of this protective film reaches 14.1 MPa, there is no corrosion (grade 0) after 1000 h of salt spray test, the mass loss rates in 5wt% HCl and 5wt% NaOH are respectively lower than 0.15% and 0.06%, and the tensile strength and tear strength reach 59.3 MPa and 152 MPa respectively. This research reveals the multi-component synergistic mechanism and provides a theoretical basis for the development of high-performance protective materials.

[0020] In the present invention, the modified boron nitride nanosheets are surface-introduced with amino groups through silanization treatment, forming hydrogen bonds with -CF2- of polyvinylidene fluoride, improving the compatibility; and the boron nitride nanosheets modified with amino silane (KH-550) are oriented in the matrix to form a dense barrier layer, delaying the diffusion of corrosive media, while the unmodified boron nitride forms discontinuous barrier layers due to agglomeration.

[0021] In the present invention, alumina is alkali-resistant (with OH- Generate Al(OH) 3 Passivation film) and SiO 2 The synergistic effect of acid resistance (stable surface hydroxyl groups) enables the composite to remain stable in both acidic and alkaline environments (loss rate < 0.2%), while single oxides have significantly deteriorated chemical resistance (loss rate > 0.2%) due to their single function.

[0022] In addition, when alumina and silica are compounded and a uniformly dispersed "core-shell" structure is formed by coating with KH560, it fills the micro-defects of the matrix and blocks the corrosion path; the tensile strength of using them separately is 14% lower than that of using them as a composite, confirming the strengthening effect of the composite.

[0023] The composite toughening agent in the present invention includes polyethersulfone and maleic anhydride grafted polyethylene, and the two are compounded to form a "rigid skeleton - flexible interface" structure. The aromatic ring structure of polyethersulfone enhances the rigidity of the matrix, while the maleic anhydride groups of MAH-g-PE react with the epoxy groups of epoxy resin to improve the interfacial bonding force. Single toughening agents will have a decrease in tear strength due to the lack of synergistic effects. Specific embodiments

[0024] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. It should be noted that in the present invention, the polyethersulfone model is Radel R-5000, and the maleic anhydride grafted polyethylene model is Exxelor PE 1040.

[0025] The present invention provides a corrosion-resistant aluminum profile protective film, which is composed of the following raw materials in parts by weight: 60 - 80 parts of polyvinylidene fluoride, 20 - 30 parts of polytetrafluoroethylene micropowder, 15 - 25 parts of epoxy resin, 5 - 8 parts of modified boron nitride nanosheets, 3 - 5 parts of silane coupling agent KH-550, 3 - 5 parts of alumina@silica composite, 8 - 12 parts of composite toughening agent, 1 - 2 parts of ultraviolet absorber, and 0.5 - 1.5 parts of antioxidant.

[0026] In a further embodiment, the polyvinylidene fluoride has a weight average molecular weight Mw = 500,000 - 600,000 and a melting point of 160 - 170 °C; the particle size of the polytetrafluoroethylene micropowder is 1 - 5 μm; and the epoxy resin is bisphenol A type epoxy E-44.

[0027] In a further embodiment, the preparation method of the modified boron nitride nanosheets includes: dispersing boron nitride nanosheets in absolute ethanol, adding 3-aminopropyltriethoxysilane, and performing ultrasonic treatment at 60-70 °C for 2-3 hours, and then centrifuging and drying to obtain amino-modified boron nitride nanosheets; the thickness of the boron nitride nanosheets is 10-50 nm, and the lateral dimension is 1-5 μm, and a regularly arranged barrier layer is formed after being modified by amino silane; the dosage ratio of the boron nitride nanosheets, absolute ethanol and 3-aminopropyltriethoxysilane is 1-2 g: 200-220 mL: 4-6 mL.

[0028] In a further embodiment, the preparation method of the alumina@silica composite includes: mixing nano-alumina and nano-silica with a weight ratio of 3:1 evenly, and drying at 60-80 °C for 100-120 min to obtain pretreated nano-powders; stirring and mixing ethanol, deionized water and acetic acid, then adding silane coupling agent KH560, and stirring at 200-300 rpm for 25-35 min to obtain a silane coupling agent solution. After adding the pretreated nano-powders thereto, ultrasonic treatment is performed at 50-60 °C for 120-140 min. During the ultrasonic process, manual stirring is performed every 20 min to prevent particle sedimentation. After centrifugal separation and ethanol washing, drying is performed at 60-80 °C to obtain the product; the dosage ratio of ethanol, deionized water, acetic acid, pretreated nano-powders, ethanol and silane coupling agent KH560 is 180-200 mL: 8-10 mL: 0.1-0.2 mL: 9-11 g: 0.3-0.4 g.

[0029] In a further embodiment, the composite toughening agent includes polyethersulfone and maleic anhydride grafted polyethylene with a weight ratio of 2-3:1; the ultraviolet absorber is UV-9, and the antioxidant is antioxidant 1010.

[0030] The preparation method of this corrosion-resistant aluminum profile protective film includes the following steps: (1) Premixing: Mixing polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene micropowder and alumina@silica composite in a high-speed mixer at 85-95 °C for 15-25 minutes, with a rotation speed of 1000-1200 rpm; (2) Modification: Adding silane coupling agent KH-550 and modified boron nitride nanosheets, and continuing to mix for 10-20 minutes; (3) Kneading: Adding the composite toughening agent, ultraviolet absorber and antioxidant, and kneading in a kneader at 170-180 °C and 60-80 rpm for 12-14 minutes; (4) Calendering and forming: Calendering into a film at 180-190 °C through a two-roll calender, with a linear speed of 5-7 m / min; (5) Post-treatment: Cooling to room temperature to obtain a protective film with a thickness of 0.2-0.4 mm.

[0031] The following will be explained with more specific embodiments.

[0032] Example 1 In this example, a corrosion-resistant aluminum profile protective film is provided, which is composed of the following raw materials in parts by weight: 70 parts of polyvinylidene fluoride, 25 parts of polytetrafluoroethylene micropowder, 20 parts of epoxy resin, 6 parts of modified boron nitride nanosheets, 4 parts of silane coupling agent KH-550, 4 parts of alumina@silica composite, 10 parts of composite toughening agent, 1.5 parts of ultraviolet absorber, and 1 part of antioxidant.

[0033] Among them, the polyvinylidene fluoride has a weight-average molecular weight Mw = 550,000 and a melting point of 165 °C; the average particle size of the polytetrafluoroethylene micropowder is 3 μm; the epoxy resin is bisphenol A type epoxy E-44.

[0034] Among them, the preparation method of the modified boron nitride nanosheets includes: dispersing boron nitride nanosheets in anhydrous ethanol, adding 3-aminopropyltriethoxysilane, and performing ultrasonic treatment at 65 °C for 2.5 hours, and then centrifuging and drying to obtain amino-modified boron nitride nanosheets; the average thickness of the boron nitride nanosheets is 30 nm, and the average lateral size is 3 μm, and a directional arrangement barrier layer is formed after amino-silane modification; the dosage ratio of boron nitride nanosheets, anhydrous ethanol and 3-aminopropyltriethoxysilane is 1.5 g: 210 mL: 5 mL.

[0035] Among them, the preparation method of the alumina@silica composite includes: mixing nano-alumina and nano-silica with a weight ratio of 3:1 evenly, and drying at 70 °C for 110 min to obtain pretreated nano-powders; stirring and mixing ethanol, deionized water and acetic acid, then adding silane coupling agent KH560, and stirring at 250 rpm for 30 min to obtain a silane coupling agent solution, adding the pretreated nano-powders thereto, and performing ultrasonic treatment at 55 °C for 130 min. During the ultrasonic process, manual stirring is performed every 20 min to prevent particle sedimentation. After centrifugal separation and ethanol washing, it is dried at 70 °C to obtain; the dosage ratio of ethanol, deionized water, acetic acid, pretreated nano-powders, ethanol and silane coupling agent KH560 is 190 mL: 9 mL: 0.15 mL: 10 g: 0.35 g.

[0036] Among them, the composite toughening agent includes polyethersulfone and maleic anhydride grafted polyethylene with a weight ratio of 2.5:1; the ultraviolet absorber is UV-9, and the antioxidant is antioxidant 1010.

[0037] The preparation method of this corrosion-resistant aluminum profile protective film includes the following steps: (1) Premixing: Mixing polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene micropowder, and alumina@silica composite in a high-speed mixer at 90 °C for 10 minutes, with a rotation speed of 1100 rpm; (2) Modification: Add silane coupling agent KH-550 and modified boron nitride nanosheets, and continue mixing for 15 minutes; (3) Internal mixing: Add composite toughening agent, UV absorber and antioxidant, and internally mix in an internal mixer at 175 °C and 70 rpm for 13 minutes; (4) Calendering: Calender into a film at 185 °C through a two-roll calender, with a linear speed of 6 m / min; (5) Post-treatment: Cool to room temperature to obtain a protective film with a thickness of 0.3 mm.

[0038] Example 2 In this example, a corrosion-resistant aluminum profile protective film is provided, which is composed of the following raw materials in parts by weight: 80 parts of polyvinylidene fluoride, 20 parts of polytetrafluoroethylene micropowder, 18 parts of epoxy resin, 7 parts of modified boron nitride nanosheets, 5 parts of silane coupling agent KH-550, 3 parts of alumina@silica composite, 12 parts of composite toughening agent, 1 part of UV absorber, and 0.5 part of antioxidant.

[0039] Among them, the polyvinylidene fluoride has a weight-average molecular weight Mw = 550,000 and a melting point of 165 °C; the average particle size of the polytetrafluoroethylene micropowder is 3 μm; the epoxy resin is bisphenol A type epoxy E-44.

[0040] Among them, the preparation method of the modified boron nitride nanosheets includes: dispersing boron nitride nanosheets in absolute ethanol, adding 3-aminopropyltriethoxysilane, and performing ultrasonic treatment at 65 °C for 2.5 hours. After centrifugation and drying, amino-functionalized modified boron nitride nanosheets are obtained; the average thickness of the boron nitride nanosheets is 30 nm, and the average lateral size is 3 μm. After being modified with amino silane, an oriented barrier layer is formed; the dosage ratio of boron nitride nanosheets, absolute ethanol, and 3-aminopropyltriethoxysilane is 1.5 g: 210 mL: 5 mL.

[0041] Among them, the preparation method of the alumina@silica composite includes: mixing nano-alumina and nano-silica with a weight ratio of 3:1 evenly, and drying at 70 °C for 110 min to obtain pretreated nano-powders; stirring and mixing ethanol, deionized water, and acetic acid, then adding silane coupling agent KH560, and stirring at 250 rpm for 30 min to obtain a silane coupling agent solution. After adding the pretreated nano-powders thereto, ultrasonic treatment is performed at 55 °C for 130 min. During the ultrasonic process, manual stirring is performed every 20 min to prevent particle sedimentation. After centrifugal separation and ethanol washing, drying is performed at 70 °C to obtain; the dosage ratio of ethanol, deionized water, acetic acid, pretreated nano-powders, ethanol, and silane coupling agent KH560 is 190 mL: 9 mL: 0.15 mL: 10 g: 0.35 g.

[0042] Among them, the composite toughening agent includes polyethersulfone and maleic anhydride grafted polyethylene with a weight ratio of 2.5:1; the ultraviolet absorber is UV-9, and the antioxidant is antioxidant 1010.

[0043] The preparation method of this corrosion-resistant aluminum profile protective film includes the following steps: (1) Premixing: Mix polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene micropowder, and alumina@silica composite in a high-speed mixer at 90°C for 10 minutes with a rotation speed of 1100 rpm; (2) Modification: Add silane coupling agent KH-550 and modified boron nitride nanosheets, and continue mixing for 15 minutes; (3) Kneading: Add the composite toughening agent, ultraviolet absorber, and antioxidant, and knead in a kneader at 175°C and 70 rpm for 13 minutes; (4) Calendering: Calender into a film at 185°C through a two-roll calender with a linear speed of 6 m / min; (5) Post-treatment: Cool to room temperature to obtain a protective film with a thickness of 0.3 mm.

[0044] Example 3 In this example, a corrosion-resistant aluminum profile protective film is provided, which is composed of the following raw materials in parts by weight: 70 parts of polyvinylidene fluoride, 25 parts of polytetrafluoroethylene micropowder, 20 parts of epoxy resin, 6 parts of modified boron nitride nanosheets, 4 parts of silane coupling agent KH-550, 4 parts of alumina@silica composite, 10 parts of composite toughening agent, 1.5 parts of ultraviolet absorber, and 1 part of antioxidant.

[0045] Among them, the polyvinylidene fluoride has a weight-average molecular weight Mw = 550,000 and a melting point of 165°C; the average particle size of the polytetrafluoroethylene micropowder is 3 μm; the epoxy resin is bisphenol A type epoxy E-44.

[0046] Among them, the preparation method of the modified boron nitride nanosheets includes: dispersing boron nitride nanosheets in absolute ethanol, adding 3-aminopropyltriethoxysilane, and performing ultrasonic treatment at 60°C for 3 hours. After centrifugation and drying, amino-functionalized modified boron nitride nanosheets are obtained; the boron nitride nanosheets have a thickness of 40 nm and a lateral size of 4 μm, and a directional arrangement barrier layer is formed after amino-silane modification; the dosage ratio of boron nitride nanosheets, absolute ethanol, and 3-aminopropyltriethoxysilane is 2 g:220 mL:4 mL.

[0047] Among them, the preparation method of the alumina@silica composite includes: mixing nano-alumina and nano-silica with a weight ratio of 3:1 evenly, and drying at 80°C for 100 min to obtain pretreated nano-powder; stirring and mixing ethanol, deionized water and acetic acid, then adding silane coupling agent KH560, and stirring at 300 rpm for 25 min to obtain a silane coupling agent solution. After adding the pretreated nano-powder thereto, ultrasonic treatment is carried out at 60°C for 120 min. During the ultrasonic process, manual stirring is carried out every 20 min to prevent particle sedimentation. After centrifugal separation and ethanol washing, it is dried at 80°C to obtain; the dosage ratios of ethanol, deionized water, acetic acid, pretreated nano-powder, ethanol and silane coupling agent KH560 are 200 mL:10 mL:0.1 mL:9 g:0.4 g.

[0048] Among them, the composite toughening agent includes polyethersulfone and maleic anhydride grafted polyethylene with a weight ratio of 2:1; the ultraviolet absorber is UV-9, and the antioxidant is antioxidant 1010.

[0049] The preparation method of this corrosion-resistant aluminum profile protective film includes the following steps: (1) Premixing: Mixing polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene micro-powder, and alumina@silica composite in a high-speed mixer at 90°C for 10 minutes, with a rotation speed of 1100 rpm; (2) Modification: Adding silane coupling agent KH-550 and modified boron nitride nanosheets, and continuing to mix for 15 minutes; (3) Kneading: Adding the composite toughening agent, ultraviolet absorber and antioxidant, and kneading in a kneader at 175°C and 70 rpm for 13 minutes; (4) Calendering: Calendering into a film at 185°C through a two-roll calender, with a linear speed of 6 m / min; (5) Post-treatment: Cooling to room temperature to obtain a protective film with a thickness of 0.3 mm.

[0050] Example 4 In this example, a corrosion-resistant aluminum profile protective film is provided, which is composed of the following raw materials in parts by weight: 60 parts of polyvinylidene fluoride, 20 parts of polytetrafluoroethylene micro-powder, 15 parts of epoxy resin, 5 parts of modified boron nitride nanosheets, 3 parts of silane coupling agent KH-550, 3 parts of alumina@silica composite, 8 parts of composite toughening agent, 1 part of ultraviolet absorber, and 0.5 part of antioxidant.

[0051] Among them, the polyvinylidene fluoride has a weight average molecular weight Mw = 500,000 and a melting point of 160°C; the average particle size of the polytetrafluoroethylene micro-powder is 1 μm; the epoxy resin is bisphenol A type epoxy E-44.

[0052] Among them, the preparation method of the modified boron nitride nanosheets includes: dispersing boron nitride nanosheets in absolute ethanol, adding 3-aminopropyltriethoxysilane, and performing ultrasonic treatment at 60°C for 2 hours. After centrifugation and drying, amino-functionalized modified boron nitride nanosheets are obtained. The average thickness of the boron nitride nanosheets is 10 nm, and the average lateral size is 1 μm. After being modified with amino silane, an oriented barrier layer is formed. The dosage ratio of boron nitride nanosheets, absolute ethanol, and 3-aminopropyltriethoxysilane is 1 g: 200 mL: 4 mL.

[0053] Among them, the preparation method of the alumina@silica composite includes: uniformly mixing nano-alumina and nano-silica with a weight ratio of 3:1, and drying at 60°C for 100 min to obtain pretreated nano-powders. Stir and mix ethanol, deionized water, and acetic acid, then add silane coupling agent KH560, and stir at 200 rpm for 25 min to obtain a silane coupling agent solution. After adding the pretreated nano-powders thereto, perform ultrasonic treatment at 50°C for 120 min. During the ultrasonic treatment, manually stir every 20 min to prevent particle sedimentation. After centrifugal separation and ethanol washing, dry at 60°C to obtain the product. The dosage ratio of ethanol, deionized water, acetic acid, pretreated nano-powders, ethanol, and silane coupling agent KH560 is 180 mL: 8 mL: 0.1 mL: 9 g: 0.3 g.

[0054] Among them, the composite toughening agent includes polyethersulfone and maleic anhydride grafted polyethylene with a weight ratio of 2:1; the ultraviolet absorber is UV-9, and the antioxidant is antioxidant 1010.

[0055] The preparation method of this corrosion-resistant aluminum profile protective film includes the following steps: (1) Premixing: Mix polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene micropowder, and alumina@silica composite in a high-speed mixer at 85°C for 15 minutes, with a rotation speed of 1000 rpm; (2) Modification: Add silane coupling agent KH-550 and modified boron nitride nanosheets, and continue mixing for 10 minutes; (3) Kneading: Add the composite toughening agent, ultraviolet absorber, and antioxidant, and knead in a kneader at 170°C and 60 rpm for 12 minutes; (4) Calendering: Calender into a film at 180°C through a two-roll calender, with a linear speed of 5 m / min; (5) Post-treatment: Cool to room temperature to obtain a protective film with a thickness of 0.3 mm.

[0056] Based on Example 1, the raw materials and related dosages are adjusted to obtain Comparative Examples 1-6. The specific material dosages are shown in Table 1 below: Table 1

[0057] Among them, in Example 3, the alumina@silica composite is replaced by modified silica, and the preparation method includes: drying silica at 70 °C for 110 min to obtain pretreated nano-powder; stirring and mixing ethanol, deionized water and acetic acid, then adding silane coupling agent KH560, and stirring for 30 min at 250 rpm to obtain a silane coupling agent solution. After adding the pretreated nano-powder thereto, ultrasonic treatment is carried out at 55 °C for 130 min. During the ultrasonic process, manual stirring is carried out every 20 min to prevent particle sedimentation. After centrifugal separation and ethanol washing, it is dried at 70 °C to obtain; the dosage ratio of ethanol, deionized water, acetic acid, pretreated nano-powder, ethanol and silane coupling agent KH560 is 190 mL: 9 mL: 0.15 mL: 10 g: 0.35 g. In Example 4, the alumina@silica composite is replaced by modified alumina, and the preparation method is the same, only the nano-powder is replaced.

[0058] Test Example 1: The following tests were carried out on the protective films prepared in the foregoing Examples 1-4 and Comparative Examples 1-6: 1. Adhesion: Test was carried out with reference to GB / T 5210-2006 "Paints and varnishes - Pull-off adhesion test". 2. Salt spray resistance: With reference to GB / T 10125-2021 Neutral salt spray test (5% NaCl, 35 °C), the blistering and peeling grades after 1000 h were evaluated. Among them, Grade 0 means no change, Grade 1 means slight discoloration, Grade 2 means local blistering, Grade 3 means edge peeling, and Grade 4 means large-area corrosion.

[0059] 3. Chemical resistance: Immersed in 5 wt% HCl (25 °C) and 10 wt% NaOH (40 °C) for 168 h, and the mass loss rate was calculated.

[0060] 4. Mechanical properties: Tensile strength was tested in accordance with GB / T 528-2009; Tear strength was tested with reference to ASTM D1004 (right-angle tear method). The tear strength was measured at a speed of 50 mm / min using a UTM-5566 (universal testing machine, Instron), and the tear strength of 5 samples was measured, and each result was expressed as the average of five measured values.

[0061] The test results are shown in Table 2 below: Table 2

[0062] Therefore, in Comparative Example 1, due to the poor dispersibility of unmodified boron nitride and the disordered barrier layer, the adhesion decreased (-27%), the corrosion resistance deteriorated (salt spray rating 3), the chemical loss rate increased significantly, and the mechanical properties decreased synchronously. In Comparative Example 2, the barrier effect of the nanosheets was missing, and the corrosive medium was easily permeable, with a salt spray rating of 4 (large-area corrosion), the worst chemical resistance, and a significant decrease in mechanical properties (tensile strength -18%). In Comparative Examples 3-4, the synergistic effect of the alumina@silica composite was missing; among them, in Comparative Example 3, the hardness was insufficient and the alkali resistance decreased (loss rate +250%), and in Comparative Example 4, the acid resistance weakened (loss rate +167%), and the mechanical properties of both were weaker than those of the composite system. In Comparative Example 5, due to the lack of composite reinforcement, the corrosion protection and mechanical properties were between those of Comparative Examples 3-4 and Comparative Example 2. In Comparative Example 6, the synergistic toughening of polyethersulfone and maleic anhydride-grafted polyethylene was missing, and the tear strength decreased by 6.6%, but other properties were close to those of Example 1 (because the toughening agent had little effect on corrosion resistance).

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A corrosion-resistant aluminum profile protective film, characterized in that: The invention is composed of the following raw materials in parts by weight: 60-80 parts of polyvinylidene fluoride, 20-30 parts of polytetrafluoroethylene powder, 15-25 parts of epoxy resin, 5-8 parts of modified boron nitride nanosheets, 3-5 parts of silane coupling agent KH-550, 3-5 parts of alumina@silicon dioxide composite, 8-12 parts of composite toughening agent, 1-2 parts of anti-ultraviolet agent and 0.5-1.5 parts of antioxidant.

2. The corrosion-resistant aluminum profile protective film according to claim 1, characterized in that: The preparation method of the modified boron nitride nanosheet comprises: dispersing the boron nitride nanosheet in anhydrous ethanol, adding 3-aminopropyltriethoxysilane, ultrasonically treating at 60-70° C. for 2-3 hours, and centrifugally drying to obtain the amino-modified boron nitride nanosheet.

3. The corrosion-resistant aluminum profile protective film according to claim 2, characterized in that: The usage ratio of the boron nitride nanosheets, anhydrous ethanol and 3-aminopropyltriethoxysilane is 1-2g:200-220mL:4-6mL.

4. The corrosion-resistant aluminum profile protective film according to claim 1, characterized in that: The preparation method of the alumina@silica composite comprises: stirring and mixing ethanol, deionized water and acetic acid, then adding silane coupling agent KH560, stirring at 200-300 rpm for 25-35 minutes to obtain a silane coupling agent solution, adding dried pretreated nano powder into the solution, ultrasonically treating at 50-60° C. for 120-140 minutes, manually stirring every 20 minutes during the ultrasonic process to prevent particle sedimentation, centrifugally separating and washing, and drying at 60-80° C. to obtain the composite.

5. The corrosion-resistant aluminum profile protective film according to claim 4, characterized in that: The preparation method of the pretreated nano powder comprises: uniformly mixing nano alumina and nano silicon dioxide in a weight ratio of 3:1, and drying at 60-80°C for 100-120 minutes to obtain the pretreated nano powder.

6. The corrosion-resistant aluminum profile protective film according to claim 4, characterized in that: The dosage ratio of the ethanol, deionized water, acetic acid, pretreated nano powder, ethanol and silane coupling agent KH560 is 180-200 mL: 8-10 mL: 0.1-0.2 mL: 9-11 g: 0.3-0.4 g.

7. The corrosion-resistant aluminum profile protective film according to claim 1, characterized in that: The composite toughening agent comprises component A and component B in a weight ratio of 2-3:1; The component A comprises polyethersulfone; and the component B comprises maleic anhydride grafted polyethylene.

8. The corrosion-resistant aluminum profile protective film according to claim 1, characterized in that: The anti-ultraviolet agent is UV-9, and the antioxidant is antioxidant 1010.

9. The method for preparing a corrosion-resistant aluminum profile protective film according to any one of claims 1 to 8, characterized in that the steps include: (1) Premixing: Mix polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene powder, and alumina@silica composite in a high-speed mixer at 85-95°C for 15-25 minutes at a speed of 1000-1200 rpm; (2) Modification: Add silane coupling agent KH-550 and modified boron nitride nanosheets and continue mixing for 10-20 minutes; (3) Internal mixing: Add composite toughening agent, anti-ultraviolet agent and antioxidant, and mix in an internal mixer at 60-80 rpm; (4) Calendering: Calendering into film at 180-190°C using a double-roll calender with a line speed of 5-7 m / min; (5) Post-treatment: Cool to room temperature to obtain a protective film with a thickness of 0.2-0.4 mm.

10. The method for preparing a corrosion-resistant aluminum profile protective film according to claim 9, characterized in that: The mixing temperature is 170-180° C., and the mixing time is 12-14 minutes.

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