Water-solvent passivated aluminum pigment, its preparation method and application

Abstract

The present application relates to a kind of water solvent passivated aluminum pigments and its preparation method and application, the preparation method includes the following steps: oily aluminum pigment, anhydrous ethanol are proportioned and heated and stirred after being added to molybdic acid-ethanol solution heat preservation stirring, after ending, temperature is reduced and pressure filtration treatment obtains filter cake;Deionized water, surfactant are proportioned and stirred after being cooled, after cooling ends, the filter cake is fully dispersed, and mixed solution of epoxy phosphate passivator-nonionic surfactant-water is added heat preservation stirring;After slow heating ends, again add the mixed solution as described above heat preservation stirring obtains reaction slurry;Reaction slurry is cooled and pressure filtration treatment, knead uniformly after, using deionized water adjusts its solid content and obtains finished product.The finished product water solvent passivated aluminum pigment prepared by using molybdic acid-ethanol solution and epoxy phosphate passivator combined step-by-step reaction process and its temperature control and other key technologies has better hydrogen evolution stability.

Description

Technical Field

[0001] This invention belongs to the field of metal coating technology, specifically relating to a water-soluble passivated aluminum pigment, its preparation method, and its application. Background Technology

[0002] Currently, commercially available water-based flake aluminum pigments are mainly divided into two categories: organophosphate passivated aluminum pigments and silica-coated aluminum pigments. Among them, passivated aluminum pigments are widely used in surface decoration, inks, coatings and other industries due to their advantages such as low cost and high metallic luster, and have a wide market coverage. However, due to the characteristics of the passivation process, passivated aluminum pigments do not have good corrosion resistance and storage stability. To overcome this defect, current technologies generally use organic solvent systems such as alcohols and ethers, and add appropriate amounts of surfactants to extend the product's shelf life by isolating oxygen. However, alcohols and ethers are hazardous chemicals, which leads to passivated aluminum pigments also being classified as hazardous chemicals. This results in stringent requirements for storage conditions, strict transportation control, and significantly increased costs. Organic solvents are highly volatile, releasing irritating odors during construction and producing high VOC (volatile organic compound) emissions. Therefore, this invention provides a water-soluble passivated aluminum pigment, its preparation method and application. Summary of the Invention

[0003] The purpose of this invention is to provide a water-soluble passivated aluminum pigment, its preparation method, and its application in order to solve the above-mentioned problems.

[0004] The present invention achieves the above objectives through the following technical solutions:

[0005] This invention provides a method for preparing a water-soluble passivated aluminum pigment, comprising the following steps:

[0006] S1: Prepare oily aluminum pigment and anhydrous ethanol in proportion and heat and stir. After heating, add molybdic acid-ethanol solution and keep it warm and stir. After keeping it warm and stirring, cool down and filter it to obtain filter cake.

[0007] S2: Prepare deionized water and surfactant in proportion and cool and stir. After cooling, fully disperse the filter cake and add a mixed solution of epoxy phosphate passivator, nonionic surfactant and water for heat preservation and stirring.

[0008] S3: After the slow heating is completed, add the mixed solution of epoxy phosphate passivator, nonionic surfactant and water again and keep it at the temperature and stir to obtain the reaction slurry;

[0009] S4: After the reaction slurry is cooled, it is filtered and kneaded evenly. Then, its solid content is adjusted with deionized water to obtain the finished water-soluble passivated aluminum pigment.

[0010] It should be noted that since the oil-based aluminum pigment is a commercially available oil-based flake ball-milled aluminum pigment, it cannot be directly dispersed in deionized water and is prone to reaction when in direct contact with water. Therefore, it is necessary to first replace the solvent of the oil-based aluminum pigment itself with an aqueous organic solvent and pre-passivate it. In this invention, anhydrous ethanol is selected as the replacement solvent, and the solvent of the reaction system after replacement is deionized water.

[0011] As a further optimization of the present invention, in step S1, the oily aluminum pigment is an oily flake-shaped ball-milled aluminum pigment with a solid content of 70-80%, the solvent is one or more of D50, D70, and H150, the particle size D50 is 11-18µm, and the particle size span is 0.8-1.0.

[0012] As a further optimization of the present invention, in step S1, the mass ratio of the oily aluminum pigment to anhydrous ethanol is (5-7):(10-21).

[0013] The heating and stirring process involves heating to 55-65℃ at a rate of 0.3-0.7℃ / min, and then maintaining the temperature and stirring at 100-150 rpm for 2-5 hours.

[0014] The mass ratio of the oily aluminum pigment to the molybdic acid-ethanol solution is (50-70):(11-38.5).

[0015] The mass ratio of molybdic acid to ethanol in the molybdic acid-ethanol solution is (1.0-3.5):(10-35).

[0016] The cooling process involves cooling the temperature to 28-32℃ before performing pressure filtration.

[0017] As a further optimization of the present invention, in step S2, the mass ratio of deionized water to surfactant is (200-350):(1.5-2.8), and the surfactant is fatty alcohol polyoxyethylene ether-9;

[0018] The cooling and stirring process involves cooling the temperature to 8-12℃ at a rate of 0.3-0.7℃ / min, and then maintaining the temperature and stirring at 100-150 rpm for 3-5 hours.

[0019] As a further optimization of the present invention, in step S3, the slow heating is to slowly heat to 45-52°C at a heating rate of 0.4-0.65°C / min, and then keep warm and stir at 100-150 rpm for 6-8 hours.

[0020] As a further optimization of the present invention, in steps S2 and S3, the mass ratio of the oily aluminum pigment to the mixed solution of epoxy phosphate passivator-nonionic surfactant-water is (50-70):(16-33.6).

[0021] The epoxy phosphate passivating agent is epoxy phosphate passivating agent DH7325;

[0022] The nonionic surfactant is a nonionic surfactant with an HLB value of 12-15, specifically fatty alcohol polyoxyethylene ether-9 (AEO9); where HLB value is the hydrophilic-lipophile balance value.

[0023] As a further optimization of the present invention, in step S4, the solid content is 50-60%;

[0024] The present invention also provides a water-soluble passivated aluminum pigment, which is prepared by the preparation method described above.

[0025] The present invention also provides an application of the water-solvent passivated aluminum pigment as described above in the preparation of water-based coatings.

[0026] The beneficial effects of this invention are as follows:

[0027] 1) This invention employs a stepwise reaction process combining molybdenum acid-ethanol solution with epoxy phosphate passivating agent and key technologies such as temperature control, which can form a highly efficient and dense composite passivation film. Through comparative testing of a water-based coating system at 50°C for 30 days, it is demonstrated that the product of this invention has better hydrogen evolution stability in coatings.

[0028] 2) This invention uses deionized water as the main solvent, has extremely low VOC content, and since it contains almost no volatile organic solvents, it has no strong irritating odor. It can be used in some industries with high environmental protection requirements, such as seed coating, and has broad application prospects. Attached Figure Description

[0029] Figure 1 This is a comparison of whiteness (A: sample without heat storage, B: sample with 30-day heat storage) and brightness (C: sample without heat storage, D: sample with 30-day heat storage) of water-based coating scraper tests in Example 2 of the present invention.

[0030] Figure 2 The whiteness comparison (A: commercially available passivated aluminum pigment, B: Example 2) and brightness comparison (C: commercially available passivated aluminum pigment, D: Example 2) of the non-heat-storage water-retaining coating scraper test of Example 2 of the present invention and commercially available passivated aluminum pigment are shown in the following figures.

[0031] Figure 3This is a comparison chart of the adhesion performance test of glass substrate and the adhesion test of high-gloss paint interlayer between the non-heat-storage sample of Example 2 of the present invention and the commercially available passivated aluminum pigment non-heat-storage sample.

[0032] Figure 4 This is a diagram showing the results of the combustible material identification test in Example 2 of the present invention. Detailed Implementation

[0033] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0034] 1. Oil-based aluminum pigment: The main material is commercially available oil-based flake-shaped ball-milled aluminum pigment (solid content 70-80%; solvent is one or more of D40 (CAS No.: 64742-94-5), D60 (CAS No.: 64742-48-9), S150 (CAS No.: 64742-94-5), particle size D50 is 11-18µm, and particle size range is 0.8-1.0; the experimental standards selected in this application are 80% solid content, D70 solvent, 13µm particle size D50, and 0.8-1.0 particle size range).

[0035] 2. Molybdic acid-ethanol solution: The mass ratio of molybdic acid to ethanol is 1.0-3.5:10-35;

[0036] 3. DH7325-AEO9-Aqueous Solution: The mass ratio of epoxy phosphate passivator DH7325 (purchased from Suzhou Qingtian New Materials Co., Ltd.), nonionic surfactant fatty alcohol polyoxyethylene ether-9 (AEO9; purchased from Jiangsu Haian Petrochemical Plant), and water is 5-10.5:1-2.1:10-21;

[0037] 4. Commercially available passivated aluminum pigments: Commercially available conventional water-based silica-coated aluminum pigments with a particle size D50 of 13µm;

[0038] Note: Unless otherwise specified, the preferred schemes were used in the following verification tests;

[0039] Unless otherwise specified, all methods used in this application are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products unless otherwise specified.

[0040] In this embodiment, a method for preparing a water-soluble passivated aluminum pigment is provided, comprising the following steps:

[0041] S1: Add 65 kg of oily aluminum pigment to a stainless steel stirred reactor, then add 182 kg of anhydrous ethanol. Set the reactor temperature to 60°C, start stirring (120 rpm) and heating (heating rate 0.5°C / min). After heating, add a pre-prepared molybdic acid-ethanol solution (3.5 kg of molybdic acid and 30 kg of ethanol), and keep it warm and stirred for 3.5 hours to ensure sufficient pre-passivation. After the warming and stirring is completed, start cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filter pressing to obtain filter cake.

[0042] S2: Add 280 kg of deionized water and 2 kg of surfactant to an empty reactor. Set the reactor temperature to 10°C, start stirring (120 rpm) and cooling (cooling rate 0.5°C / min). After cooling is complete, add the filter cake to a stainless steel stirred reactor and stir thoroughly to disperse it completely. After dispersion, add DH7325-AEO9- aqueous solution (of which DH7325 is 10.5 kg of epoxy phosphate passivating agent, AEO9 is 1 kg of nonionic surfactant, and water is 10 kg) to the reactor and stir at low temperature (10-20°C) for 4 hours to ensure thorough passivation treatment.

[0043] S3: After the low-temperature stirring is completed, set the temperature of the reactor to 50℃ and slowly heat it at a heating rate of 0.55℃ / min. After the heating is completed, add DH7325-AEO9-water solution again (of which, 5 kg of epoxy phosphate passivating agent DH7325, 2.1 kg of nonionic surfactant AEO9, and 21 kg of water are added), and keep it heated and stirred at 120 rpm for 6.5 hours.

[0044] S4: After stirring is completed, begin cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filtration. Then, use a kneader to knead it evenly and use deionized water to adjust the solid content to 56%, thus obtaining the finished water-soluble passivated aluminum pigment.

[0045] Example 2

[0046] In this embodiment, a method for preparing a water-soluble passivated aluminum pigment is provided, comprising the following steps:

[0047] S1: Add 65 kg of oily aluminum pigment to a stainless steel stirred reactor, then add 182 kg of anhydrous ethanol. Set the reactor temperature to 60°C, start (120 rpm) and heat (heating rate is 0.5°C / min). After heating, add a pre-prepared molybdic acid-ethanol solution (2.2 kg of molybdic acid and 30 kg of ethanol), and keep it warm and stirred for 3.5 hours to ensure sufficient pre-passivation. After the heat preservation and stirring are completed, start cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filter pressing to obtain filter cake.

[0048] S2: Add 280 kg of deionized water and 2 kg of surfactant to an empty reactor. Set the reactor temperature to 10°C, start stirring (120 rpm) and cooling (cooling rate 0.5°C / min). After cooling is complete, add the filter cake to a stainless steel stirred reactor and stir thoroughly to disperse it completely. After dispersion, add DH7325-AEO9- aqueous solution (of which DH7325 is 6.5 kg of epoxy phosphate passivating agent, AEO9 is 1.5 kg of nonionic surfactant, and water is 18 kg) to the reactor and stir at low temperature (10-20°C) for 4 hours to ensure sufficient passivation treatment.

[0049] S3: After the low-temperature stirring is completed, set the temperature of the reactor to 50℃ and slowly heat it at a heating rate of 0.55℃ / min. After the heating is completed, add DH7325-AEO9-water solution again (of which, 7.5 kg of epoxy phosphate passivating agent DH7325, 1.5 kg of nonionic surfactant AEO9, and 15 kg of water are added), and keep it heated and stirred at 120 rpm for 6.5 hours.

[0050] S4: After stirring is completed, begin cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filtration. Then, use a kneader to knead it evenly and use deionized water to adjust the solid content to 56%, thus obtaining the finished water-soluble passivated aluminum pigment.

[0051] Example 3

[0052] In this embodiment, a method for preparing a water-soluble passivated aluminum pigment is provided, comprising the following steps:

[0053] S1: Add 65 kg of oily aluminum pigment to a stainless steel stirred reactor, then add 182 kg of anhydrous ethanol. Set the reactor temperature to 60°C, start stirring (120 rpm) and heating (heating rate 0.5°C / min). After heating, add a pre-prepared molybdic acid-ethanol solution (1.5 kg of molybdic acid and 30 kg of ethanol), and keep it warm and stirred for 3.5 hours to ensure sufficient pre-passivation. After the warming and stirring is completed, start cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filter pressing to obtain filter cake.

[0054] S2: Add 280 kg of deionized water and 2 kg of surfactant to an empty reactor. Set the reactor temperature to 10°C, start stirring (120 rpm) and cooling (cooling rate 0.5°C / min). After cooling is complete, add the filter cake to a stainless steel stirred reactor and stir thoroughly to disperse it completely. After dispersion, add DH7325-AEO9- aqueous solution (of which 5 kg of epoxy phosphate passivating agent DH7325, 2.1 kg of nonionic surfactant AEO9, and 21 kg of water) to the reactor and stir at low temperature (10-20°C) for 4 hours to ensure thorough passivation treatment.

[0055] S3: After the low-temperature stirring is completed, set the temperature of the reactor to 50℃ and slowly heat it at a heating rate of 0.55℃ / min. After the heating is completed, add DH7325-AEO9-water solution again (wherein, the epoxy phosphate passivating agent DH7325 is 10.5kg, the nonionic surfactant AEO9 is 1kg, and the water is 10kg), and keep it heated and stirred at 120rpm for 6.5 hours.

[0056] S4: After stirring is completed, begin cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filtration. Then, use a kneader to knead it evenly and use deionized water to adjust the solid content to 56%, thus obtaining the finished water-soluble passivated aluminum pigment.

[0057] Comparative Example 1

[0058] The difference between this comparative example and Example 2 is that in this comparative example, molybdic acid is replaced with an equal mass of orthophosphoric acid, while all other aspects remain the same as in Example 2.

[0059] Comparative Example 2

[0060] In this comparative example, the difference from Example 2 is that sodium molybdate of equal mass is used to replace molybdic acid, while all other aspects remain the same as in Example 2.

[0061] Comparative Example 3

[0062] In this comparative example, the difference from Example 2 is that in steps S2 and S3, an equal mass of alkyl phosphate ester is used to replace the epoxy phosphate ester passivating agent, while the rest is the same as in Example 2.

[0063] Comparative Example 4

[0064] In this comparative example, the difference from Example 2 is that in step S2, an equal mass of alkyl phosphate ester is used to replace the epoxy phosphate ester passivating agent, while the rest remains the same as in Example 2.

[0065] Comparative Example 5

[0066] In this comparative example, the difference from Example 2 is that in step S3, an equal mass of alkyl phosphate ester is used to replace the epoxy phosphate ester passivating agent, while the rest remains the same as in Example 2.

[0067] Comparative Example 6

[0068] In this comparative example, a method for preparing a water-soluble passivated aluminum pigment is provided, comprising the following steps:

[0069] S1: Add 65 kg of oily aluminum pigment to a stainless steel stirred reactor, then add 182 kg of anhydrous ethanol. Set the reactor temperature to 60°C, start stirring (120 rpm) and heating (heating rate 0.5°C / min). After heating, add a pre-prepared molybdic acid-ethanol solution (2.2 kg of molybdic acid and 30 kg of ethanol), and keep it warm and stirred for 3.5 hours to ensure sufficient pre-passivation. After the warming and stirring is completed, start cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filter pressing to obtain filter cake.

[0070] S2: Add 280 kg of deionized water and 2 kg of surfactant to an empty reactor. Set the reactor temperature to 10°C, start stirring (120 rpm) and cooling (cooling rate 0.5°C / min). After cooling is complete, add the filter cake to a stainless steel stirred reactor and stir thoroughly to disperse it completely. After dispersion, add DH7325-AEO9- aqueous solution (of which DH7325 is 6.5 kg of epoxy phosphate passivating agent, AEO9 is 1.5 kg of nonionic surfactant, and water is 18 kg) to the reactor and stir at low temperature (10-20°C) for 4 hours to ensure sufficient passivation treatment.

[0071] S3: After the low-temperature stirring is completed, the temperature of the reactor is set to 10℃. DH7325-AEO9-water solution is added again (of which 7.5 kg of epoxy phosphate passivating agent DH7325, 1.5 kg of nonionic surfactant AEO9, and 15 kg of water are added). The reactor is stirred at 120 rpm for 6.5 hours.

[0072] S4: After stirring is complete, use a peristaltic pump to pump the reaction slurry into a filter press for filtration, then use a kneader to knead it evenly, and use deionized water to adjust the solid content to 56%, thus obtaining the finished water-soluble passivated aluminum pigment.

[0073] Comparative Example 7

[0074] In this comparative example, a method for preparing a water-soluble passivated aluminum pigment is provided, comprising the following steps:

[0075] S1: Add 65 kg of oily aluminum pigment to a stainless steel stirred reactor, then add 182 kg of anhydrous ethanol. Set the reactor temperature to 60°C, start stirring (120 rpm) and heating (heating rate 0.5°C / min). After heating, add a pre-prepared molybdic acid-ethanol solution (2.2 kg of molybdic acid and 30 kg of ethanol), and keep it warm and stirred for 3.5 hours to ensure sufficient pre-passivation. After the warming and stirring is completed, start cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filter pressing to obtain filter cake.

[0076] S2: Add 280 kg of deionized water and 2 kg of surfactant to an empty reactor. Set the reactor temperature to 50°C, start stirring (120 rpm) and heating, and slowly heat at a rate of 0.55°C / min. After heating is complete, add the filter cake to a stainless steel stirred reactor and stir thoroughly to disperse it completely. After dispersion, add DH7325-AEO9- aqueous solution (of which DH7325 is 6.5 kg of epoxy phosphate passivating agent, AEO9 is 1.5 kg of nonionic surfactant, and 18 kg of water) to the reactor and stir at high temperature (48-52°C) for 4 hours to ensure thorough passivation treatment.

[0077] S3: After the high-temperature stirring is completed, the temperature of the reactor is set to 50℃, and DH7325-AEO9-water solution is added again (of which, 7.5 kg of epoxy phosphate passivating agent DH7325, 1.5 kg of nonionic surfactant AEO9, and 15 kg of water are added), and the mixture is stirred at 120 rpm for 6.5 hours.

[0078] S4: After stirring is completed, begin cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filtration. Then, use a kneader to knead it evenly and use deionized water to adjust the solid content to 56%, thus obtaining the finished water-soluble passivated aluminum pigment.

[0079] Comparative Example 8

[0080] In this comparative example, a method for preparing a water-soluble passivated aluminum pigment is provided, comprising the following steps:

[0081] S1: Add 65 kg of oily aluminum pigment to a stainless steel stirred reactor, then add 182 kg of anhydrous ethanol. Set the reactor temperature to 60°C, start stirring (120 rpm) and heating (heating rate 0.5°C / min). After heating, add a pre-prepared molybdic acid-ethanol solution (2.2 kg of molybdic acid and 30 kg of ethanol), and keep it warm and stirred for 3.5 hours to ensure sufficient pre-passivation. After the warming and stirring is completed, start cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filter pressing to obtain filter cake.

[0082] S2: Add 280 kg of deionized water and 2 kg of surfactant to an empty reactor. Set the reactor temperature to 10°C, start stirring (120 rpm) and cooling (cooling rate 0.5°C / min). After cooling is complete, add the filter cake to a stainless steel stirred reactor and stir thoroughly to disperse it completely. After dispersion, add DH7325-AEO9- aqueous solution (of which DH7325 is 14 kg of epoxy phosphate passivating agent, AEO9 is 3 kg of nonionic surfactant, and water is 33 kg) to the reactor and stir at low temperature (10-20°C) for 4 hours to ensure thorough passivation treatment.

[0083] S3: After the low-temperature stirring is completed, set the temperature of the reactor to 50℃ and slowly increase the temperature at a rate of 0.55℃ / min. After the temperature increase is completed, keep the temperature at 120 rpm and stir for 6.5 hours.

[0084] S4: After stirring is completed, begin cooling. When the cooling temperature is below 30°C, use a peristaltic pump to pump the reaction slurry into a filter press for filtration. Then, use a kneader to knead it evenly and use deionized water to adjust the solid content to 56%, thus obtaining the finished water-soluble passivated aluminum pigment.

[0085] III. Experimental Verification

[0086] 1. Hydrogen evolution test

[0087] Experimental Method: Test coating samples (Examples 1-3) and control coating samples (Comparative Examples 1-8 and commercially available passivated aluminum pigment) were prepared by mixing 8% water-soluble passivated aluminum pigment (from the same batch, with a solid content of 50%) with 16% water and 76% water-based acrylic emulsion (the water-based acrylic emulsion was from the same batch). The pH was adjusted to 9, and the total mass was 270g. All samples were placed in the same hydrogen evolution apparatus and tested at a constant temperature of 50℃ for 30 days (a constant temperature water bath at 50℃ is an accelerated test simulating normal product storage; 30 days at 50℃ is equivalent to approximately six months of storage at room temperature). The amount of hydrogen produced in each group of samples was observed (gas release unit: ml). The results are shown in Table 1.

[0088] Table 1. Hydrogen Evolution Test Data Recording Sheet

[0089] ;

[0090] Experimental conclusions: As shown in Table 1, the aluminum pigments treated with molybdic acid-ethanol solution in Examples 1-3 had significantly lower gas release rates at 15 and 30 days than all comparative examples and commercially available products. Among them, Example 1 performed the best, proving that molybdic acid has a significant advantage in passivating aluminum pigments. The comparison revealed that the specific chemical structure of molybdic acid plays an irreplaceable role in forming an effective passivation film.

[0091] Comparative analysis revealed that replacing the epoxy phosphate passivator with an alkyl phosphate in steps S2 and S3 significantly increased the outgassing rate, confirming that the epoxy phosphate passivator can form a more stable composite passivation layer in the stepwise reaction. Furthermore, the stepwise reaction process combining molybdate-ethanol solution with the epoxy phosphate passivator, along with key technologies such as temperature control, can form a highly efficient and dense composite passivation film, significantly improving the product's storage stability and safety.

[0092] 2. Hue detection

[0093] Waterborne coating scraper tests (50µm wet film preparer) were performed using the unheated and 30-day heat-stored samples from Example 2, as well as the unheated samples from Example 2 and the commercially available passivated aluminum pigment unheated samples.

[0094] Test results are as follows Figure 1-2As shown in the test results above, compared with the product that did not undergo 30 days of heat storage, the product after heat storage did not suffer any loss in whiteness, brightness, or metallic feel, nor did it exhibit agglomeration or coarsening. Therefore, it can be determined that the product of this invention has good thermal stability and meets the product performance requirements. Compared with commercially available passivated aluminum pigment samples, it was found that under normal conditions, this invention has whiteness, brightness, and metallic feel comparable to commercially available passivated aluminum pigment products. Since the passivation process itself has very little hue loss, it can be determined that although this invention uses water as a solvent, no reaction occurs between water and aluminum pigment during the reaction process.

[0095] 3. Adhesion performance test of glass substrate and adhesion test of high-gloss paint interlayer.

[0096] Primer: The water-soluble passivated aluminum pigment (after heat storage) and commercially available passivated aluminum pigment (8% water-soluble passivated aluminum pigment / commercially available passivated aluminum pigment + 16% water + 76% water-based acrylic emulsion, the water-based acrylic emulsion is from the same batch, with a solid content of 50%, after heat storage) were sprayed onto the surface of the glass substrate. After spraying, the primer was flash-dried at 80°C for 5 minutes, and then heated to 170°C and baked for 30 minutes until the primer was completely dry.

[0097] Topcoat: Add 10wt% red pigment and 20wt% water to the water-based acrylic resin emulsion, mix well, bake at 80℃ for 5 minutes, and then bake at 170℃ for 30 minutes.

[0098] After the primer and topcoat were applied (wet-to-dry test), the adhesion performance of the glass substrate and the adhesion of the high-gloss paint layers were tested by cross-cut test (under the same experimental conditions).

[0099] Test results are as follows Figure 3 As shown, the reason for using the wet-to-dry test in the above test method is that, in the conventional wet-to-dry board preparation process, the fluidity between layers promotes the fusion of interlayer components, thereby enhancing the interlayer adhesion. The wet-to-dry test eliminates this effect and allows for a more intuitive observation of the difference in product adhesion. As can be seen from the above conclusions, the present invention has excellent adhesion in the wet-to-dry baking paint system.

[0100] 4. Combustible material identification test

[0101] In Example 2 of this invention, the water-solvent passivated aluminum pigment was subjected to a combustible identification test. The test standard was the evaluation criteria for combustible materials given in the seventh revision of the United Nations Manual of Tests and Criteria. The test method was to make a continuous strip or powder strip of the commercial product, about 250 mm long, 20 mm wide and 10 mm high, and place it on a cold, impermeable, low thermal conductivity base plate. A high-temperature flame (minimum temperature of 1000°C) sprayed from a gas nozzle (10 mm in diameter) was used to burn one end of the powder strip until the powder ignited. The maximum burning time was 2 minutes. It should be noted whether the combustion spreads 200 mm along the powder strip within the 2-minute test time. If the substance cannot ignite and burn along the powder strip with flame or smoke for 200 mm within the 2-minute test time, the substance should not be classified as a flammable solid.

[0102] Experimental results are as follows Figure 4 As shown, the results indicate that the spray gun continued to ignite, and local melting and sparks appeared in the product. The phenomenon disappeared immediately after the spray gun was turned off, and no flame appeared. There was no reignition within 1 minute. This shows that the present invention is non-flammable. Since no harmful substances are added or generated in the manufacturing process of the present invention, it can be concluded that the present invention falls within the category of non-hazardous chemicals.

[0103] The seed coating industry requires silver paste to be environmentally friendly, resistant to weak alkali corrosion, low in odor, high in brightness, and free of harmful substances that affect seeds. This product uses water as a solvent and is characterized by being environmentally friendly, low in odor, and free of harmful solvents. Furthermore, based on hydrogen evolution experiments in a weak alkali system with pH=9, it is known that it has good resistance to weak alkalis. In summary, this invention has good stability, superior adhesion, and superior metallic brightness. In addition, since this invention is non-flammable and does not contain or generate any harmful substances, it is a non-hazardous chemical, which reduces its storage and transportation conditions and lowers storage and transportation costs.

[0104] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a water-soluble passivated aluminum pigment, characterized in that: Includes the following steps: S1: Prepare oily aluminum pigment and anhydrous ethanol in proportion and heat and stir. After heating, add molybdic acid-ethanol solution and keep it warm and stir. After keeping it warm and stirring, cool down and filter it to obtain filter cake. The mass ratio of the oily aluminum pigment to the molybdic acid-ethanol solution is (50-70):(11-38.5). The mass ratio of molybdic acid to ethanol in the molybdic acid-ethanol solution is (1.0-3.5):(10-35). S2: Prepare deionized water and surfactant in proportion and cool and stir. After cooling, fully disperse the filter cake and add a mixed solution of epoxy phosphate passivator, nonionic surfactant and water for heat preservation and stirring. The mass ratio of deionized water to surfactant is (200-350):(1.5-2.8); the surfactant is fatty alcohol polyoxyethylene ether-9. S3: After the slow heating is completed, add the mixed solution of epoxy phosphate passivator, nonionic surfactant and water again and keep it at the temperature and stir to obtain the reaction slurry; The mass ratio of the oily aluminum pigment to the mixed solution of epoxy phosphate passivator-nonionic surfactant-water is (50-70):(16-33.6); in the mixed solution, the mass ratio of epoxy phosphate passivator, nonionic surfactant, and water is 5-10.5:1-2.1:10-21. The epoxy phosphate passivating agent is epoxy phosphate passivating agent DH7325; The nonionic surfactant is fatty alcohol polyoxyethylene ether-9; S4: After the reaction slurry is cooled, it is filtered and kneaded evenly. Then, its solid content is adjusted with deionized water to obtain the finished water-soluble passivated aluminum pigment.

2. The method for preparing a water-soluble passivated aluminum pigment according to claim 1, characterized in that: In step S1, the oily aluminum pigment is an oily flake ball-milled aluminum pigment with a solid content of 70-80%, and the solvent is one or more of D50, D70, and H150. The particle size D50 is 11-18µm and the particle size range is 0.8-1.

0.

3. The method for preparing a water-soluble passivated aluminum pigment according to claim 1, characterized in that: In step S1, the mass ratio of the oily aluminum pigment to anhydrous ethanol is (5-7):(10-21). The heating and stirring process involves heating to 55-65℃ at a rate of 0.3-0.7℃ / min, and then maintaining the temperature and stirring at 100-150 rpm for 2-5 hours. The cooling process involves cooling the temperature to 28-32℃ before performing pressure filtration.

4. The method for preparing a water-soluble passivated aluminum pigment according to claim 1, characterized in that: In step S2, the cooling and stirring involves cooling to 8-12℃ at a cooling rate of 0.3-0.7℃ / min, and then maintaining the temperature and stirring at 100-150 rpm for 3-5 hours.

5. The method for preparing a water-soluble passivated aluminum pigment according to claim 1, characterized in that: In step S3, the slow heating is to slowly heat the temperature to 45-52℃ at a heating rate of 0.4-0.65℃ / min, and then keep it at the temperature and stir at 100-150 rpm for 6-8 hours.

6. The method for preparing a water-soluble passivated aluminum pigment according to claim 1, characterized in that: In step S4, the solid content is 50-60%.

7. A water-soluble passivated aluminum pigment, characterized in that: It is prepared by any one of the preparation methods described in claims 1-6.

8. The application of the water-solvent passivated aluminum pigment as described in claim 7 in the preparation of water-based coatings.

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