Lotus leaf shield sealant, preparation method thereof and application in anodic oxidation

Abstract

The application belongs to the technical field of anodic oxidation, and provides a lotus-leaf-shield sealing agent, a preparation method thereof and application in anodic oxidation. The lotus-leaf-shield sealing agent provided by the application adopts a sealing-catalysis component and a hydrophobic film-forming component as main components, wherein the sealing-catalysis component comprises a salt containing at least one metal ion selected from aluminum ion, lithium ion, lanthanum ion and yttrium ion; and the hydrophobic film-forming component comprises a long-chain alkyl phosphate ester compound or a salt thereof. The lotus-leaf-shield sealing agent can simultaneously realize hole sealing and hydrophobic and oleophobic treatment of an anodic oxidation film, the surface water contact angle of the prepared aluminum alloy anodic oxidation product is greater than or equal to 120 degrees, the oil contact angle is greater than or equal to 65 degrees, the product has a "lotus-leaf effect" surface, is resistant to fingerprints and easy to clean, the functional layer has excellent adhesion to the substrate, and the wear resistance is much higher than that of a traditional coating process, without using fluorine-containing raw materials, and is environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of anodizing technology, and more specifically, to a lotus leaf shield sealant, its preparation method, and its application in anodizing. Background Technology

[0002] Currently, aluminum alloy anodizing technology is widely used in consumer electronics, automobiles, building materials, and other fields to improve the wear resistance, corrosion resistance, and aesthetics of products. The anodizing process typically includes the following steps: degreasing, anodizing, dyeing, sealing, washing, and drying. However, the anodized film produced by conventional anodizing processes has a porous hydrophilic structure with a water contact angle of approximately 70° and an oil contact angle of approximately 15°. It lacks hydrophobic and oleophobic properties, easily attracts fingerprints and oil stains, is difficult to clean, and does not exhibit the "lotus effect."

[0003] To impart hydrophobic and oleophobic properties to anodized products, existing technologies typically employ post-treatment methods, which involve adding an additional surface coating process after anodizing and sealing. These methods mainly include the following: (1) Anti-fingerprint oil immersion process: An immersion tank is added to the anodizing production line to immerse the product in anti-fingerprint oil containing fluorine or silane.

[0004] (2) Anti-fingerprint paint spraying process: After the anodizing process, the product is transferred to the spraying line and sprayed with a special resin coating containing fluorine or silicon.

[0005] (3) Anti-fingerprint oil vapor deposition process: A layer of low surface energy material is deposited on the surface by vacuum vapor deposition.

[0006] However, all of the above methods share a common fundamental flaw, namely: (1) Process complexity: In addition to the main anodizing process, an additional independent process is required, which leads to a longer production process and reduced production efficiency.

[0007] (2) High cost: It requires additional investment in equipment (such as tanks, spraying lines, vacuum coating machines, etc.), space and increased energy consumption, and consumes additional chemical raw materials, which significantly increases production costs.

[0008] (3) Poor coating durability: The functional layer formed by the above method is mainly physically attached to the anodic oxide substrate by physical adhesion or weak van der Waals forces. The bonding force is weak and it is easy to fail after friction, scratching or long-term use, resulting in insufficient functional durability.

[0009] (4) Environmental pressure: Most of them require the use of fluorinated compounds (PFAS) to give the coating hydrophobic properties, which is not environmentally friendly.

[0010] Therefore, there is an urgent need to develop a method that can impart hydrophobic and oleophobic properties to anodized parts without the need for additional hydrophobic and oleophobic functionalization steps. This would reduce the number of operation steps, lower costs, provide coatings with high durability and excellent wear resistance, and eliminate the need for fluorine-containing raw materials, making it environmentally friendly. Summary of the Invention

[0011] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a lotus leaf shield sealant, its preparation method, and its application in anodizing. The lotus leaf shield sealant provided by this invention can be further applied to the anodizing process, simultaneously achieving sealing and hydrophobic / oleophobic properties. It integrates pore sealing treatment with durable hydrophobic / oleophobic functionalization treatment into one step, eliminating the need for additional hydrophobic / oleophobic functionalization steps, simplifying the operation process, saving costs, and improving efficiency. Moreover, the resulting anodized film exhibits strong adhesion to the anodized substrate, high wear resistance, and durability.

[0012] A first aspect of the present invention provides a lotus leaf shield sealant.

[0013] Specifically, a lotus leaf shield sealing agent includes the following components: a pore-sealing catalytic component and a hydrophobic film-forming component; The sealing catalyst component includes aluminum ions (Al). 3+ Lithium ion (Li) + ), lanthanum ion (La) 3+ ), Yttrium ions (Y 3 + A salt of at least one metal ion in ); The hydrophobic film-forming component includes long-chain alkyl phosphate compounds or their salts.

[0014] The lotus leaf shield sealant of this invention catalyzes a hydration reaction in the pore walls of the anodic oxide film, generating boehmite (AlOOH), thus sealing the pores of the anodic oxide part. Meanwhile, the phosphate groups in the long-chain alkyl phosphate compound or its salt chemically bond with the alumina surface or boehmite layer to form a strong "Al-OP" chemical anchoring layer. This layer exhibits a much stronger bond with the substrate than traditional coatings based on physical adsorption, resulting in extremely high wear resistance and long-lasting performance. Simultaneously, its outwardly arranged long-chain alkyl groups form a low surface energy layer, thereby achieving hydrophobic and oleophobic properties. Therefore, treatment with the lotus leaf shield sealant of this invention simultaneously achieves sealing and hydrophobic / oleophobic properties, eliminating the need for additional hydrophobic and oleophobic treatment steps after obtaining the aluminum alloy anodic oxide film. This reduces operational steps, simplifies the production process, lowers costs, and improves production efficiency.

[0015] Preferably, the lotus leaf shield sealant contains aluminum ions (Al). 3+ Lithium ion (Li) + ), lanthanum ion (La) 3+), Yttrium ions (Y 3+ The concentration of a salt of at least one metal ion in the composition is 0.1-5.0 g / L.

[0016] Preferably, the concentration of the long-chain alkyl phosphate compound or its salt in the lotus leaf shield sealant is 0.5-20.0 g / L.

[0017] Preferably, the long-chain alkyl phosphate compound is a straight-chain alkyl or branched-chain alkyl phosphate compound with C12-C24 carbon atoms.

[0018] More preferably, the long-chain alkyl phosphate compound is at least one selected from mono-n-dodecyl phosphate, sodium hexadecyl phosphate, potassium (1-octadecyl) phosphate, 2-ethylhexyl phosphate, and potassium lauryl phosphate.

[0019] Preferably, the components of the lotus leaf shield sealant further include water. The present invention uses an aqueous solution of the lotus leaf shield sealant.

[0020] A second aspect of the present invention provides a method for preparing a lotus leaf shield sealant.

[0021] A method for preparing a lotus leaf shield sealant includes the following steps: The components are mixed to obtain the lotus leaf shield sealant.

[0022] A third aspect of the present invention provides an application of the lotus leaf shield sealant.

[0023] Application of a lotus leaf shield sealant in the preparation of hydrophobic and oleophobic products or anodized products.

[0024] A fourth aspect of the present invention provides a method of using lotus leaf shield sealant.

[0025] A method for using a lotus leaf shield sealant includes the following steps: After anodizing and dyeing, the parts to be treated are immersed in the lotus leaf shield sealant and treated at 90-100℃ for 10-50 minutes.

[0026] In the process of using the lotus leaf shield sealant, pore sealing and hydrophobic / oleophobic transformation occur simultaneously: On the one hand, pore sealing: under the catalysis of metal ions, the pore walls of the oxide film undergo a hydration reaction to generate boehmite (AlOOH), thus sealing the pores; on the other hand, hydrophobic / oleophobic transformation: the phosphate groups in the long-chain alkyl phosphate compound or its salt form a strong "Al-OP" anchoring layer through chemical bonding with the alumina surface or boehmite layer. Simultaneously, the outwardly oriented long-chain alkyl groups are densely arranged to form a low surface energy layer, thereby obtaining a hydrophobic and oleophobic surface. Therefore, after treatment with the lotus leaf shield sealant of this invention, pore sealing and hydrophobic / oleophobic transformation are achieved simultaneously in a "one-step" process. While producing anodized aluminum alloy products, it also imparts hydrophobic and oleophobic properties, and can bond well with the anodized surface, exhibiting excellent wear resistance.

[0027] Preferably, the immersion in the lotus leaf shield sealant is performed at 93-98°C for 10-40 minutes.

[0028] Preferably, the part to be processed is an aluminum alloy product.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: The lotus leaf shield sealant provided by this invention uses a pore-sealing catalytic component and a hydrophobic film-forming component as its main components. The pore-sealing catalytic component includes a salt containing at least one metal ion selected from aluminum, lithium, lanthanum, and yttrium ions. The hydrophobic film-forming component includes a long-chain alkyl phosphate compound or its salt. The metal ions catalyze a hydration reaction in the pore walls of the oxide film, generating boehmite (AlOOH), thus sealing the pores of the anodized part. The phosphate groups in the long-chain alkyl phosphate compound or its salt form a strong "Al-OP" chemical anchoring layer through chemical bonding with the alumina surface or boehmite layer. This layer exhibits a much stronger bond with the substrate than traditional coatings based on physical adsorption, resulting in extremely high wear resistance and long-lasting performance, and also forms a low surface energy layer. The aluminum alloy anodized product obtained by this invention has a water contact angle ≥120° and an oil contact angle ≥65°, exhibiting a "lotus leaf effect" surface. The product is fingerprint-resistant, easy to clean, and the functional layer has excellent adhesion to the substrate, with wear resistance far exceeding that of traditional coating processes. The lotus leaf shield sealing agent treatment of the present invention integrates pore sealing and hydrophobic and oleophobic functionalization into the same process, eliminating the need for traditional additional hydrophobic and oleophobic treatments (such as soaking, spraying, vapor deposition and other anti-fingerprint coating processes), greatly shortening the production process, improving production efficiency, saving equipment, costs and energy consumption, and is more environmentally friendly as it does not use fluorine-containing raw materials. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the lotus leaf shield sealant used in Application Example 1 of the present invention; Figure 2This is a schematic diagram of the water contact angle of the anodized part obtained after treatment with the lotus leaf shield sealant in Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the contact angle of hexadecane oil on the anodized part obtained after treatment with the lotus leaf shield sealant in Embodiment 1 of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0032] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0033] The "lotus leaf effect" described in this invention refers to a surface that is both hydrophobic and oleophobic.

[0034] Example 1 A lotus leaf shield sealant, based on mass concentration, consists of the following components: Yttrium nitrate 1.0 g / L, Lanthanum nitrate 0.5 g / L, Mono-n-dodecyl phosphate 5.0 g / L, Potassium salt of (1-octadecyl) phosphate 5.0 g / L, 2-ethylhexyl phosphate 2.0 g / L.

[0035] The preparation method of the above-mentioned lotus leaf shield sealant includes the following steps: Yttrium nitrate, lanthanum nitrate, mono-n-dodecyl phosphate, potassium salt of (1-octadecyl) phosphate, and 2-ethylhexyl phosphate are added to water and mixed evenly to obtain lotus leaf shield sealing agent.

[0036] Example 2 A lotus leaf shield sealant, differing from Example 1 in that mono-dodecyl phosphate is replaced with an equal amount and concentration of potassium lauryl phosphate.

[0037] Example 3 A lotus leaf shield sealant, which differs from Example 1 in that mono-dodecyl phosphate is replaced with an equal amount and concentration of potassium (1-octadecyl) phosphate.

[0038] Example 4 A lotus leaf shield sealing agent, which differs from Example 1 in that the concentration of mono-n-dodecyl phosphate is changed to 2 g / L.

[0039] Example 5 A lotus leaf shield sealing agent, which differs from Example 1 in that the concentration of mono-n-dodecyl phosphate is changed to 0.5 g / L.

[0040] Comparative Example 1 (without hydrophobic film-forming components) A treatment solution, which differs from Example 1 in that it does not contain mono-n-dodecyl phosphate, potassium salt of (1-octadecyl) phosphate, and 2-ethylhexyl phosphate.

[0041] Comparative Example 2 A treatment solution differs from that of Example 1 in that mono-dodecyl phosphate is replaced with an equal amount and concentration of nonylphenol polyoxyethylene ether phosphate.

[0042] Application Example 1 A method for using lotus leaf shield sealant, illustrated in the diagram below. Figure 1 As shown, it includes the following steps: The 6063 aluminum alloy test piece, which has undergone conventional anodizing treatment (the conventional anodizing treatment steps include: aluminum material -- degreasing -- water washing -- alkaline corrosion -- water washing -- black film peeling -- water washing -- chemical polishing -- water washing -- black film peeling -- water washing -- sulfuric acid anodizing (voltage 13-15V, 40-60min, sulfuric acid concentration 180-220g / L) -- water washing -- dyeing -- water washing -- sealing -- water washing -- drying), was immersed in the lotus leaf shield sealing agent of Example 1 and kept at 90℃ for 30min. After being taken out, it was washed with water and dried.

[0043] Product effectiveness test 1. Testing Method (1) Water contact angle: obtained by optical contact angle measuring instrument; (2) Contact angle of n-hexadecane oil: obtained by optical contact angle measuring instrument; (3) Neutral salt spray test: Refer to GBT 12967.3-2022 for testing; Judgment criteria: "OK" is indicated by visual inspection if there are no defects such as peeling, pitting, or bubbles.

[0044] (4) Stain resistance test: Refer to ASTM B136 test; Test conditions: nitric acid 40%, dye solution 20g / l; Test method: 1. First, add one drop of nitric acid (40%), leave for 2 minutes, then thoroughly rinse the area with tap water and dry with a lint-free cloth. Next, add one drop of staining solution to the same spot in the same area and leave for 5 minutes.

[0045] 2. Rinse thoroughly with tap water and then wipe dry with a lint-free cloth.

[0046] Judgment method: "OK" is indicated by the absence of visible residual solution on the coating surface.

[0047] (5) Adhesion Test: Refer to ASTM D3359 test. 1. Use a cross-cut adhesion tester to penetrate the coating, then apply 3M #610 tape (or equivalent). 2. Completely adhere the tape to the scratched area. Hold one end of the tape at a right angle to the test surface and tear it off instantly. Judgment criteria: No substrate exposed on the coating surface; 4B minimum (less than 5% of the removed area); indicates "OK". (6) Abrasion resistance: RCA paper tape is abrasion resistant. The test is conducted according to ASTM F2357. The test environment is: temperature 25±2℃, humidity 30%~60%; fixed load: 175 gf for RCA system; special paper tape: Norman paper tape. The test cycle is 150 cycles. Judgment criterion: "OK" is indicated when the coating surface does not expose the substrate.

[0048] 2. Test Results Table 1 shows the performance test results of each application example and comparison application example 1.

[0049] As shown in the table above, after treatment with the lotus leaf shield sealant of Example 1 of this invention, the water contact angle of the anodized part can reach more than 120° (see the schematic diagram of the water droplet angle). Figure 2 As shown), the contact angle of hexadecane oil can reach over 65° (see the diagram of oil droplet angle). Figure 3 As shown in the figure, it has hydrophobic and oleophobic properties.

[0050] Compared to Application Example 1, Application Example 1 does not have hydrophobic and oleophobic properties because it does not contain long-chain alkyl phosphate compounds or their salt hydrophobic film-forming components.

[0051] Compared to Application Example 1, the alkyl polyoxyethylene ether phosphate used in Application Example 2, although also a commonly used surfactant, has a polyoxyethylene ether hydrophilic chain that disrupts the formation of the hydrophobic layer, thus failing to impart hydrophobic properties to the anodic oxide film. In contrast, the long-chain alkyl phosphate compound or its salt selected in this invention does not contain polyoxyethylene ether (PEO) hydrophilic chains, and can impart hydrophobic properties to the anodic oxide component.

Claims

1. A lotus leaf shield sealant, characterized in that, It includes the following components: pore-sealing catalyst and hydrophobic film-forming component; The sealing catalyst component includes a salt containing at least one metal ion selected from aluminum ions, lithium ions, lanthanum ions, and yttrium ions; The hydrophobic film-forming component includes long-chain alkyl phosphate compounds or their salts.

2. The lotus leaf shield sealant according to claim 1, characterized in that, The concentration of the salt containing at least one metal ion selected from aluminum ions, lithium ions, lanthanum ions, and yttrium ions in the lotus leaf shield sealant is 0.1-5.0 g / L.

3. The lotus leaf shield sealant according to claim 1, characterized in that, The concentration of the long-chain alkyl phosphate compound or its salt in the lotus leaf shield sealant is 0.5-20.0 g / L.

4. The lotus leaf shield sealant according to claim 1, characterized in that, The long-chain alkyl phosphate compound is a straight-chain alkyl or branched-chain alkyl phosphate compound with C12-C24 carbon atoms.

5. The lotus leaf shield sealant according to claim 4, characterized in that, The long-chain alkyl phosphate compound is at least one of mono-n-dodecyl phosphate, sodium hexadecyl phosphate, potassium (1-octadecyl) phosphate, 2-ethylhexyl phosphate, and potassium lauryl phosphate.

6. The method for preparing the lotus leaf shield sealant according to any one of claims 1-5, characterized in that, Includes the following steps: The components are mixed to obtain the lotus leaf shield sealant.

7. The use of the lotus leaf shield sealant according to any one of claims 1-5 in the preparation of hydrophobic and oleophobic products or anodized products.

8. The method of using the lotus leaf shield sealant according to any one of claims 1-5, characterized in that, Includes the following steps: After anodizing and dyeing, the parts to be treated are immersed in the lotus leaf shield sealant and treated at 90-100℃ for 10-50 minutes.

9. The method of use according to claim 8, characterized in that, Immerse in the lotus leaf shield sealant and treat at 93-98℃ for 10-40 minutes.

10. The method of use according to claim 8, characterized in that, The part to be processed is an aluminum alloy product.

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