A three-layer coated aluminum powder pigment and preparation method thereof

Abstract

This invention belongs to the field of micro-fine powder materials technology, specifically relating to a three-layer coated aluminum powder pigment and its preparation method. The preparation method of the aluminum powder pigment is as follows: Pretreated aluminum powder is added to a solvent, ultrasonically treated to form a suspension, tetraethyl orthosilicate is added dropwise, the pH is adjusted, and the mixture is heated to react, resulting in an inner layer of SiO2-coated aluminum powder; epoxy resin and acetone are mixed evenly, and a silane coupling agent, the inner layer of SiO2-coated aluminum powder, and a curing agent are added, followed by heating to react, resulting in a silicon-resin double-layer coated aluminum powder; the silicon-resin double-layer coated aluminum powder is placed in an ALD reaction chamber, evacuated, heated and maintained at a constant temperature, first purged with SiCl4, then with nitrogen, then with water vapor, and then with nitrogen again, repeating this cycle 100-300 times to deposit SiO2 layer by layer, and after cooling and drying, the final product is obtained. This method solves the defects of traditional aluminum powder pigments such as easy oxidation, interlayer delamination, and limited functionality.

Description

Technical Field

[0001] This invention belongs to the field of fine powder materials technology, specifically relating to a three-layer coated aluminum powder pigment and its preparation method. Background Technology

[0002] With increasing global emphasis on environmental protection, countries have introduced strict environmental regulations to rigorously control the emission of volatile organic compounds (VOCs). Powder coatings, as a pollution-free and highly efficient coating, will have even broader development prospects and their application areas will continue to expand under the impetus of environmental policies. Since the development of wet production technology for aluminum powder in 1910, aluminum powder has been mass-produced and integrated into production and daily life, making it one of the most widely used and diverse types of metallic pigments. Due to its metallic luster, color variation, and low price, it is mainly used in the production of coatings, printing inks, and plastic materials, and has been widely applied in many industries such as automobiles, electronics, building materials, home appliances, printing inks, instruments and equipment, shipbuilding, aircraft, plastic materials, and textiles. Aluminum pigments used in coatings require strong acid and alkali resistance. However, flake aluminum powder has a large specific surface area and is easily corroded by acidic and alkaline media when exposed to air, seriously affecting the performance of aluminum pigments. Therefore, surface treatment is necessary.

[0003] Coated aluminum powder pigments are functional materials that modify aluminum powder through surface coating technology. Their core objective is to improve the corrosion resistance, chemical stability, dispersibility, and optical properties of aluminum powder through the coating layer, thereby expanding its applications in coatings, inks, plastics, cosmetics, and other fields. Currently, there are two main methods for silicon-coated aluminum powder pigments: single-layer silicon coating and double-layer silicon-resin coating. However, existing aluminum powder pigments have the following problems: 1) Single-layer inorganic silicon (SiO2) coated aluminum powder pigments are brittle and prone to cracking under external forces such as coating spraying and mechanical grinding; 2) Silicon-resin coated aluminum powder pigments are prone to interlayer delamination due to poor compatibility at the inorganic (SiO2) / organic (resin) interface, especially under thermal cycling or mechanical stress, leading to performance degradation; 3) Silicon-resin coatings with a single inorganic layer contain microcracks or pinholes, making them susceptible to corrosion by corrosive media (such as Cl). - 4) The outer layer of the silicon-resin-coated aluminum powder pigment resin is prone to softening or decomposition at high temperatures (>200℃), leading to coating failure. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a three-layer coated aluminum powder pigment and its preparation method. The aluminum powder pigment of this invention has an inorganic-organic-inorganic three-layer composite structure. Through the physical isolation of the aluminum matrix by the dense silica inner layer, the stress buffering and chemical bonding strengthening of the intermediate resin layer, and the surface protection of the functionalized silica outer layer, a synergistic protective system is formed, fundamentally solving the inherent defects of traditional aluminum powder pigments such as easy oxidation, interlayer delamination, and limited functionality.

[0005] One of the objectives of this invention is to provide a method for preparing a three-layer coated aluminum powder pigment.

[0006] The second objective of this invention is to provide a three-layer coated aluminum powder pigment.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a three-layer coated aluminum powder pigment includes the following steps:

[0009] (1) Add the pretreated aluminum powder to the solvent, sonicate it to form a suspension, add tetraethyl orthosilicate, adjust the pH, and heat the reaction. After the reaction is completed, centrifuge, wash and dry the solution to obtain aluminum powder with inner SiO2 coating.

[0010] (2) Mix epoxy resin and acetone evenly, add silane coupling agent, inner layer SiO2 coated aluminum powder and curing agent, heat to react, centrifuge, wash and dry the solution after the reaction to obtain silicone-resin double-layer coated aluminum powder.

[0011] (3) Place the silicon-resin double-layer coated aluminum powder in the ALD reaction chamber, evacuate, heat and maintain constant temperature, first introduce SiCl4, then introduce nitrogen to purge, then introduce water vapor, then introduce nitrogen to purge again, repeat this cycle 100-300 times, deposit SiO2 layer by layer, cool and dry to obtain the product.

[0012] Further, the pretreated aluminum powder in step (1) is prepared by the following method:

[0013] Aluminum powder is added to hydrochloric acid solution and ultrasonically treated. The treated solution is then centrifuged, washed, and dried to obtain the final product.

[0014] Furthermore, the average particle size of the aluminum powder is 10-20µm, the mass ratio of the aluminum powder to the hydrochloric acid solution is (10-25):(100-300), the concentration of the hydrochloric acid solution is 1mol / L, the ultrasonic power is 200-300w, the frequency is 40kHz, and the duration is 15-30min.

[0015] This invention employs acid pickling and activation to pretreat aluminum powder, which thoroughly removes the oxide layer (Al2O3) and impurities from the aluminum powder surface. Under nitrogen protection, secondary oxidation of the pretreated aluminum powder is prevented. The pretreated aluminum powder of this invention improves the adhesion of the coating layer and reduces the risk of subsequent coating layer peeling.

[0016] This invention employs gradient pH control: the inner layer reacts at a higher pH (10-11) for rapid film formation, while the outer layer has a slightly lower pH (9-10) to ensure film uniformity. The inner layer of SiO2 coated aluminum powder obtained by this invention forms a dense inorganic barrier, blocking the oxidation and corrosion of the aluminum substrate.

[0017] Further, in step (1), the ratio of aluminum powder, tetraethyl orthosilicate, and solvent used in the pretreatment is 10-20g: 5-10mL: 200-400mL, and the solvent is ethanol or n-propanol.

[0018] Further, in step (1), the time for adding tetraethyl orthosilicate is 10-20 min; the pH is adjusted to 10-11; the reaction temperature is 50-60℃ and the time is 6-8 h; the drying temperature is 50-70℃ and the time is 4-6 h.

[0019] Further, in step (2), the mass ratio of epoxy resin, silane coupling agent, inner SiO2-coated aluminum powder, and curing agent is (5-10):(0.1-0.2):(8-20):(2.5-5); the epoxy resin is epoxy resin E-44; the silane coupling agent is KH-550; the curing agent is polyamide 650; and the ratio of epoxy resin to acetone is 5-10g:50-100mL.

[0020] Further, the heating reaction in step (2) is carried out at a temperature of 70-90°C for 3-5 hours; the drying temperature is 50-60°C for 5-8 hours.

[0021] Furthermore, after step (3) evacuation, the vacuum level is ≤5×10⁻⁶. -4 Pa; the heating temperature is 150℃; the SiCl4 pulse time is 0.2-2s, the nitrogen purging time is 20-30s, the water vapor pulse time is 0.3-2s, and the nitrogen purging time is 20-30s again.

[0022] Furthermore, in step (3), the deposition thickness for each cycle is 0.1 nm.

[0023] The three-layer coated aluminum powder pigment of the present invention is prepared by the above-described preparation method.

[0024] The silicon-resin double-layer coated aluminum powder of this invention has a flexible buffer layer, which enhances impact resistance and improves interlayer bonding. On the one hand, the interfacial bonding is enhanced by forming chemical bonds (Si-OC) between epoxy groups (-O-) and silane coupling agent (KH-550). On the other hand, an in-situ polymerization process is used to directly polymerize on the surface of the aluminum powder, avoiding compatibility issues between the resin prepolymer and the SiO2 layer.

[0025] This invention employs ALD ultrathin deposition technology, which uses alternating pulsed precursors (SiCl4 and H2O) to deposit atomically thin SiO2 layer by layer, with a thickness of approximately 0.1 nm per cycle.

[0026] This invention uses atomic layer deposition (ALD) technology to form nanoscale SiO2 on the surface of aluminum powder with a double layer of silicon-resin coating, which seals the defects in the resin layer and enhances scratch resistance, high temperature resistance and chemical stability.

[0027] Compared with the prior art, the beneficial effects of this invention are as follows:

[0028] (1) The core advantage of this invention stems from its innovative inorganic-organic-inorganic three-layer composite structure. Through the physical isolation of the aluminum substrate by the dense silica inner layer, the stress buffering and chemical bonding strengthening of the intermediate resin layer, and the surface protection of the functionalized silica outer layer, a synergistic protective system is formed, fundamentally solving the inherent defects of traditional aluminum powder pigments such as easy oxidation, interlayer delamination, and single function. In response to extreme environmental challenges, the synergistic design of high-temperature resistant resin and gradient thermal expansion coefficient endows the coating with excellent thermal stability, which can withstand drastic temperature changes and chemical corrosion.

[0029] (2) In terms of production process, the present invention adopts a combination of ALD technology and sol-gel technology to balance coating accuracy and cost control. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention.

[0032] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0033] Example 1

[0034] A method for preparing a three-layer coated aluminum powder pigment includes the following steps:

[0035] Step 1: Take 15g of aluminum powder with an average particle size of 20μm (purity > 99.5%) and add it to 200mL of 1M hydrochloric acid solution. Sonicate the mixture (frequency 40kHz, power 300W) for 20min. After sonication, centrifuge the mixture at 8000rpm for 5min and discard the supernatant. Add deionized water and repeat centrifugation until the pH of the supernatant reaches 7. Place the centrifuged aluminum powder in a vacuum drying oven and dry at 60℃ for 6h to obtain pretreated aluminum powder.

[0036] Step 2: Add 10g of pretreated aluminum powder to 200mL of ethanol and ultrasonically disperse for 30min (200W, pulse mode) to form a stable suspension. Transfer the suspension to a reaction vessel, start a magnetic stirrer at 500rpm, and add 5mL of tetraethyl orthosilicate (TEOS) dropwise while stirring for 10min. After the addition is complete, add ammonia dropwise until the solution pH=10.0, raise the temperature to 50℃, increase the stirring speed to 800rpm, and react for 6h. After the reaction is complete and cooled to room temperature, collect the coated aluminum powder by centrifugation, wash three times with ethanol, and vacuum dry (60℃, 4h) to obtain aluminum powder coated with inner layer SiO2.

[0037] Step 3: Mix 5g of epoxy resin E-44 with 50mL of acetone, add 0.1g of KH-550, and ultrasonically disperse for 10min (ultrasonic power 150W). Add 8g of inner-layer SiO2 coated aluminum powder to the above solution and ultrasonically treat for 20min to form a stable suspension. Transfer the suspension to a reaction vessel, start a magnetic stirrer, adjust the speed to 600rpm, and slowly add 2.5g of polyamide 650 dropwise while stirring. Raise the temperature to 70℃ and continue the reaction for 4h. After the reaction is complete and cooled to room temperature, collect the coated product by centrifugation, wash twice with acetone, and vacuum dry (50℃, 6h); obtain silicone-resin double-layer coated aluminum powder.

[0038] Step 4: Evenly spread the coated aluminum powder obtained in Step 3 onto the ALD sample tray and load it into the reaction chamber. Reduce the pressure in the reaction chamber to a basic vacuum of 5 × 10⁻⁶. -4The substrate was heated to 150°C and held at that temperature. A SiCl4 pulse was first introduced for 0.2 s, followed by N2 purging for 20 s, then an H2O pulse for 0.3 s, and finally N2 purging for 20 s. This cycle was repeated 300 times, with a deposition thickness of approximately 0.1 nm per cycle. After deposition, the sample was cooled to below 80°C under nitrogen protection, removed, and stored in a dry nitrogen cabinet. A three-layer SiO2-resin-SiO2 coated aluminum powder pigment was obtained.

[0039] This embodiment also provides a three-layer coated aluminum powder pigment, which is prepared by the above-described method.

[0040] Example 2

[0041] A method for preparing a three-layer coated aluminum powder pigment includes the following steps:

[0042] Step 1: Take 22g of aluminum powder with an average particle size of 10μm (purity > 99.5%) and add it to 300mL of 1M hydrochloric acid solution. Sonicate the mixture (frequency 40kHz, power 300W) for 20min. After sonication, centrifuge the mixture at 8000rpm for 5min and discard the supernatant. Add deionized water and repeat centrifugation until the pH of the supernatant reaches 7. Place the centrifuged aluminum powder in a vacuum drying oven and dry at 60℃ for 6h to obtain pretreated aluminum powder.

[0043] Step 2: Add 20g of pretreated aluminum powder to 350mL of ethanol and ultrasonically disperse for 30min (200W, pulse mode) to form a stable suspension. Transfer the suspension to a reaction vessel, start a magnetic stirrer, adjust the speed to 500rpm, and add 10mL of TEOS dropwise while stirring for 20min. After the addition is complete, add ammonia dropwise until the solution pH=10.2, raise the temperature to 55℃, increase the stirring speed to 800rpm, and react for 8h. After the reaction is complete and cooled to room temperature, collect the coated aluminum powder by centrifugation, wash it three times with ethanol, and vacuum dry (60℃, 4h) to obtain aluminum powder coated with inner layer SiO2.

[0044] Step 3: Mix 10g of epoxy resin E-44 with 80mL of acetone, add 0.2g of KH-550, and ultrasonically disperse for 10min (power 150W). Add 18g of inner-layer SiO2 coated aluminum powder to the above solution and ultrasonically treat for 20min to form a stable suspension. Transfer the suspension to a reaction vessel, start a magnetic stirrer, adjust the speed to 600rpm, and slowly add 4g of polyamide 650 while stirring. Raise the temperature to 70℃ and continue the reaction for 4h. After the reaction is complete and cooled to room temperature, collect the coated product by centrifugation, wash twice with acetone, and vacuum dry (50℃, 6h); obtain silicone-resin double-layer coated aluminum powder.

[0045] Step 4: Evenly spread the coated aluminum powder obtained in Step 3 onto the ALD sample tray and load it into the reaction chamber. Reduce the pressure in the reaction chamber to a basic vacuum of 5 × 10⁻⁶. -4 The substrate was heated to 150°C and held at that temperature. A SiCl4 pulse was first introduced for 0.2 s, followed by N2 purging for 20 s, then an H2O pulse for 0.3 s, and finally N2 purging for 20 s. This cycle was repeated 200 times, with a deposition thickness of approximately 0.1 nm per cycle. After deposition, the sample was cooled to below 80°C under nitrogen protection, removed, and stored in a dry nitrogen cabinet; a SiO2-resin-SiO2 three-layer coated aluminum powder pigment was obtained.

[0046] This embodiment also provides a three-layer coated aluminum powder pigment, which is prepared by the above-described method.

[0047] Example 3

[0048] A method for preparing a three-layer coated aluminum powder pigment includes the following steps:

[0049] Step 1: Take 13g of aluminum powder with an average particle size of 20μm (purity > 99.5%) and add it to 150mL of 1M hydrochloric acid solution. Sonicate the mixture (frequency 40kHz, power 300W) for 20min. After the reaction, centrifuge the mixture at 8000rpm for 5min and discard the supernatant. Add deionized water and repeat centrifugation until the pH of the supernatant reaches 7. Place the centrifuged aluminum powder in a vacuum drying oven and dry at 60℃ for 6h to obtain pretreated aluminum powder.

[0050] Step 2: Add 10g of pretreated aluminum powder to 200mL of ethanol and ultrasonically disperse for 30min (200W, pulse mode) to form a stable suspension. Transfer the suspension to a reaction vessel, start a magnetic stirrer, adjust the speed to 500rpm, and add 10mL of TEOS dropwise while stirring for 20min. After the addition is complete, add ammonia dropwise until the solution pH=11.2, raise the temperature to 50℃, increase the stirring speed to 800rpm, and react for 8h. After the reaction is complete and cooled to room temperature, collect the coated aluminum powder by centrifugation, wash it three times with ethanol, and vacuum dry (60℃, 4h). Obtain aluminum powder with inner SiO2 coating.

[0051] Step 3: Mix 6g of epoxy resin E-44 with 80mL of acetone, add 0.2g of KH-550, and ultrasonically disperse for 10min (power 150W). Add 8g of inner-layer SiO2 coated aluminum powder to the above solution and ultrasonically treat for 20min to form a stable suspension. Transfer the suspension to a reaction vessel, start a magnetic stirrer, adjust the speed to 600rpm, and slowly add 3g of polyamide 650 while stirring. Heat to 90℃ and continue the reaction for 4h. After the reaction is complete and cooled to room temperature, collect the coated product by centrifugation, wash twice with acetone, and vacuum dry (50℃, 6h); obtain silicone-resin double-layer coated aluminum powder.

[0052] Step 4: Evenly spread the coated aluminum powder obtained in Step 3 onto the ALD sample tray and load it into the reaction chamber. Reduce the pressure in the reaction chamber to a basic vacuum of 5 × 10⁻⁶. -4 The substrate was heated to 150°C and held at that temperature. A SiCl4 pulse was first introduced for 0.2 s, followed by N2 purging for 20 s, then an H2O pulse for 0.3 s, and finally N2 purging for 20 s. This cycle was repeated 300 times, with a deposition thickness of approximately 0.1 nm per cycle. After deposition, the sample was cooled to below 80°C under nitrogen protection, removed, and stored in a dry nitrogen cabinet; a three-layer SiO2-resin-SiO2 coated aluminum powder pigment was obtained.

[0053] This embodiment also provides a three-layer coated aluminum powder pigment, which is prepared by the above-described method.

[0054] Example 4

[0055] A method for preparing a three-layer coated aluminum powder pigment includes the following steps:

[0056] Step 1: Take 20g of aluminum powder with an average particle size of 20μm (purity > 99.5%) and add it to 400mL of 1M hydrochloric acid solution. Sonicate the mixture (frequency 40kHz, power 300W) for 20min. After the reaction, centrifuge the mixture at 8000rpm for 5min and discard the supernatant. Add deionized water and repeat centrifugation until the pH of the supernatant reaches 7. Place the centrifuged aluminum powder in a vacuum drying oven and dry at 60℃ for 6h to obtain pretreated aluminum powder.

[0057] Step 2: Add 10g of pretreated aluminum powder to 280mL of n-propanol and ultrasonically disperse for 20min (200W, pulse mode) to form a stable suspension. Transfer the suspension to a reaction vessel, start a magnetic stirrer, adjust the speed to 500rpm, and add 10mL of TEOS dropwise while stirring for 20min. After the addition is complete, add ammonia dropwise until the solution pH=11.0, raise the temperature to 60℃, increase the stirring speed to 800rpm, and react for 6h. After the reaction is complete and cooled to room temperature, collect the coated aluminum powder by centrifugation, wash three times with n-propanol, and vacuum dry (60℃, 4h); obtain aluminum powder with inner SiO2 coating.

[0058] Step 3: Mix 5g of epoxy resin E-44 with 50mL of acetone, add 0.1g of KH-550, and ultrasonically disperse for 10min (power 150W). Add 8g of inner-layer SiO2 coated aluminum powder to the above solution and ultrasonically treat for 20min to form a stable suspension. Transfer the suspension to a reaction vessel, start a magnetic stirrer, adjust the speed to 600rpm, and slowly add 2.5g of polyamide 650 dropwise while stirring. Raise the temperature to 70℃ and continue the reaction for 4h. After the reaction is complete and cooled to room temperature, collect the coated product by centrifugation, wash twice with acetone, and vacuum dry (50℃, 6h); to obtain silicone-resin double-layer coated aluminum powder.

[0059] Step 4: Evenly spread the coated aluminum powder obtained in Step 3 onto the ALD sample tray and load it into the reaction chamber. Reduce the pressure in the reaction chamber to a basic vacuum of 5 × 10⁻⁶. -4 The substrate was heated to 150°C and held at that temperature. A SiCl4 pulse was first introduced for 0.2 s, followed by N2 purging for 20 s, then an H2O pulse for 0.3 s, and finally N2 purging for 20 s. This cycle was repeated 300 times, with a deposition thickness of approximately 0.1 nm per cycle. After deposition, the sample was cooled to below 80°C under nitrogen protection, removed, and stored in a dry nitrogen cabinet; a three-layer SiO2-resin-SiO2 coated aluminum powder pigment was obtained.

[0060] This embodiment also provides a three-layer coated aluminum powder pigment, which is prepared by the above-described method.

[0061] Comparative Example 1

[0062] This comparative example provides a method for preparing a silicon-resin double-layer coated aluminum powder pigment, including the following steps:

[0063] Step 1: Take 10g of aluminum powder with an average particle size of 20μm (purity >99.5%) and add it to 200mL of ethanol. Disperse the powder ultrasonically for 30min (200W, pulse mode) to form a stable suspension. Transfer the suspension to a reaction vessel and start a magnetic stirrer at 500rpm. While stirring, add 5mL of tetraethyl orthosilicate (TEOS) dropwise, continuing stirring for 10min. After the addition is complete, add ammonia dropwise until the solution pH=10.0. Raise the temperature to 50℃ and increase the stirring speed to 800rpm, reacting for 6h. After the reaction is complete and cooled to room temperature, collect the coated aluminum powder by centrifugation, wash three times with ethanol, and vacuum dry (60℃, 4h) to obtain aluminum powder coated with an inner layer of SiO2.

[0064] Step 2: Add 5g of epoxy resin E-44 to 0.1g of KH-550 and ultrasonically disperse for 10min (ultrasonic power 150W). Add 8g of inner-layer SiO2 coated aluminum powder to the above solution and ultrasonically treat for 20min to form a stable suspension. Centrifuge the suspension, collect the coated product, and vacuum dry (50℃, 6h); to obtain silicon-resin double-layer coated aluminum powder.

[0065] Comparative Example 2

[0066] This comparative example provides a method for preparing a double-layer coated aluminum powder pigment. The difference from Example 1 is that the fourth step is omitted, resulting in a silicon-resin double-layer coated aluminum powder.

[0067] Comparative Example 3

[0068] This comparative example provides a method for preparing a three-layer coated aluminum powder pigment. The difference from Example 1 is that the fourth step of deposition is repeated 100 times.

[0069] Test case

[0070] The performance of the products obtained in Examples 1-4 and Comparative Examples 1-3 of this invention was tested, as follows:

[0071] The test samples of Examples 1-4 and Comparative Examples 1-3 were mixed with base powder (AENOO20A model purchased from Guangdong Aiyue Powder Coating Co., Ltd.) at an addition amount of 2wt%, and then electrostatically sprayed onto stainless steel sheet substrates (except for short-term high-temperature resistance tests, the detailed test process is as follows):

[0072] 1. Corrosion resistance: The coating surface corrosion was observed by performing an accelerated acetic acid salt spray test (AASS) for 1000 hours as specified in GB / T 10125.

[0073] 2. Impact resistance test: The coating is impacted by a 4 mm diameter steel ball dropped from a height of 50 cm, and the area of ​​peeling is evaluated.

[0074] 3. High temperature resistance:

[0075] (1) Short-term temperature resistance: After spreading the test sample evenly on the sample tray, put it into the oven and bake at 300℃ for 2 hours, and observe the color change.

[0076] (2) Long-term temperature resistance: Place the electrostatic sprayed sample in an oven and bake at 150℃ for 300h, and observe the integrity of the coating.

[0077] 4. Interface compatibility:

[0078] The test sample was subjected to 100 cycles of thermal cycling at -40℃ for 30 minutes and then at 150℃ for 30 minutes, and the coating cracking was observed.

[0079] The test results are shown in Table 1.

[0080] Table 1

[0081]

[0082] As can be seen from the above test results, the products obtained in Examples 1-4 of the present invention have good corrosion resistance, impact resistance, resistance to short-term and long-term high temperatures, and interfacial compatibility.

[0083] Compared with Example 1, the overall performance of Comparative Examples 1-3 is worse. Among them, Comparative Examples 1 and 2 have worse corrosion resistance, impact resistance and interfacial compatibility, while Comparative Example 3 has slightly better overall performance.

[0084] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a three-layer coated aluminum powder pigment, characterized in that, Includes the following steps: (1) Add the pretreated aluminum powder to the solvent, sonicate it to form a suspension, add tetraethyl orthosilicate, adjust the pH and heat the reaction, centrifuge, wash and dry the solution after the reaction to obtain aluminum powder with inner SiO2 coating. (2) Mix epoxy resin and acetone evenly, add silane coupling agent, inner layer SiO2 coated aluminum powder and curing agent, heat to react, centrifuge, wash and dry the solution after the reaction to obtain silicone-resin double-layer coated aluminum powder. (3) Place the silicon-resin double-layer coated aluminum powder in the ALD reaction chamber, evacuate, heat and maintain constant temperature, first introduce SiCl4, then introduce nitrogen to purge, then introduce water vapor, then introduce nitrogen to purge again, repeat this cycle 100-300 times, deposit SiO2 layer by layer, cool and dry to obtain the product.

2. The method for preparing the three-layer coated aluminum powder pigment according to claim 1, characterized in that, The pretreated aluminum powder in step (1) is prepared by the following method: Aluminum powder is added to hydrochloric acid solution and ultrasonically treated. The treated solution is then centrifuged, washed, and dried to obtain the final product.

3. The method for preparing the three-layer coated aluminum powder pigment according to claim 2, characterized in that, The aluminum powder has an average particle size of 10-20µm, the mass ratio of the aluminum powder to the hydrochloric acid solution is (10-25):(100-300), the concentration of the hydrochloric acid solution is 1mol / L, the ultrasonic power is 200-300w, the frequency is 40kHz, and the duration is 15-30min.

4. The method for preparing the three-layer coated aluminum powder pigment according to claim 1, characterized in that, The ratio of aluminum powder, tetraethyl orthosilicate, and solvent used in step (1) is 10-20g: 5-10mL: 200-400mL, and the solvent is ethanol or n-propanol.

5. The method for preparing a three-layer coated aluminum powder pigment according to claim 1, characterized in that, In step (1), the time for adding tetraethyl orthosilicate is 10-20 min; the pH is adjusted to 10-11; the reaction temperature is 50-60℃ and the time is 6-8 h; the drying temperature is 50-70℃ and the time is 4-6 h.

6. The method for preparing a three-layer coated aluminum powder pigment according to claim 1, characterized in that, In step (2), the mass ratio of epoxy resin, silane coupling agent, inner SiO2-coated aluminum powder, and curing agent is (5-10):(0.1-0.2):(8-20):(2.5-5); the epoxy resin is epoxy resin E-44; the silane coupling agent is KH-550; the curing agent is polyamide 650; and the ratio of epoxy resin to acetone is 5-10g:50-100mL.

7. The method for preparing a three-layer coated aluminum powder pigment according to claim 1, characterized in that, The heating reaction in step (2) is carried out at a temperature of 70-90℃ for 3-5 hours; the drying temperature is 50-60℃ for 5-8 hours.

8. The method for preparing a three-layer coated aluminum powder pigment according to claim 1, characterized in that, Step (3) After vacuuming, the vacuum level is ≤5×10 -4 Pa; the heating temperature is 150℃; the SiCl4 pulse time is 0.2-2s, the nitrogen purging time is 20-30s, the water vapor pulse time is 0.3-2s, and the nitrogen purging time is 20-30s again.

9. The method for preparing a three-layer coated aluminum powder pigment according to claim 1, characterized in that, In step (3), the deposition thickness for each cycle is 0.1 nm.

10. A three-layer coated aluminum powder pigment, characterized in that, The three-layer coated aluminum powder pigment is prepared using the preparation method described in any one of claims 1-9.

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