Aqueous floating aluminum pigments and methods for their preparation

Abstract

The application provides a water-based floating aluminum pigment and a preparation method thereof, and the preparation method comprises the following steps: carrying out grafting reaction on aluminum pigment and a silane coupling agent under an alkaline regulator to graft the silane coupling agent on the surface of aluminum particles, so that pretreated aluminum pigment is obtained; and carrying out polymerization reaction on the pretreated aluminum pigment, a hydrophilic monomer and a hydrophobic monomer under an initiator, so that an amphiphilic polymer is coated on the surface of the aluminum particles, thereby obtaining the water-based floating aluminum pigment. The water-based floating aluminum pigment and the preparation method thereof are characterized in that: after the aluminum pigment is modified by using the silane coupling agent, an amphiphilic polymer is coated on the surface of the aluminum particles, so that the floating performance of the obtained aluminum pigment is improved, and the corrosion resistance of the aluminum pigment is also improved.

Description

Technical Field

[0001] This invention relates to the field of pigment technology, and in particular to a water-based floating aluminum pigment and its preparation method. Background Technology

[0002] Aluminum pigments are important metallic pigments, and due to their unique aesthetic effects and corrosion resistance, they have been widely used in anti-corrosion coatings, industrial coatings, automotive coatings, interior and exterior architectural coatings, household appliance coatings, printing inks, and the plastics processing industry in recent years. With increasing environmental awareness, traditional organic solvent-based coatings will inevitably be replaced by environmentally friendly water-based coatings. Aluminum pigments used in water-based coatings have different requirements than those used in solvent-based coatings: firstly, the pigment surface must be hydrophilic, effectively dispersed in water, and able to float; secondly, it must maintain high chemical stability in the aqueous medium. However, traditional water-based floating aluminum pigment preparation processes often use simple surface treatment of oil-based aluminum pigments to achieve a floating effect. The resulting water-based floating aluminum pigments do not have ideal floating properties or storage stability. Furthermore, aluminum is chemically reactive and readily reacts with oxygen or water. Simple treatment of oil-based aluminum pigments provides poor protection and results in poor resistance to acid and alkali corrosion and poor storage stability (such as blackening and gas expansion).

[0003] Currently, coating waterborne aluminum pigments with silica for use in waterborne coatings is a mainstream technological development trend. However, as the market becomes increasingly segmented and demanding, the brightness of waterborne silica-coated products is struggling to meet market requirements. Therefore, exploring novel modification methods for aluminum pigments to further improve their floating properties and corrosion resistance is of great significance for promoting their application in coatings, printing inks, and other industries. Summary of the Invention

[0004] Based on the technical problems existing in the background art, the present invention proposes an aqueous floating aluminum pigment and its preparation method. After modifying the aluminum pigment with a silane coupling agent, a layer of amphiphilic polymer is coated on the surface of the aluminum particles, which aims to improve the floating performance of the obtained aluminum pigment and at the same time improve its corrosion resistance.

[0005] The present invention provides a method for preparing a water-based floating aluminum pigment, comprising the following steps:

[0006] S1. Grafting reaction of aluminum pigment and silane coupling agent under alkaline regulator, grafting silane coupling agent onto the surface of aluminum particles to obtain pretreated aluminum pigment.

[0007] S2. The pretreated aluminum pigment is polymerized with hydrophilic and hydrophobic monomers under initiator conditions to coat the surface of aluminum particles with amphiphilic polymers, thereby obtaining the water-based floating aluminum pigment.

[0008] In this invention, aluminum pigments are pretreated to graft silane coupling agents onto their surfaces, thereby altering the reactivity of the aluminum particles and providing a foundation for subsequent reactions. Subsequently, an amphiphilic polymer composed of hydrophilic and hydrophobic monomers is in situ coated onto the surface of the aluminum particles (i.e., the aluminum pigment). This improves the dispersion performance of the aluminum pigment in aqueous polar media, reduces the surface free energy of the aluminum pigment, making it easier for the pigment to migrate from the matrix to the surface, enhancing its floating properties, and maintaining gloss. Furthermore, it effectively isolates the aluminum pigment from contact with other corrosive media such as acids and alkalis, resulting in good stability and acid and alkali resistance in aqueous systems.

[0009] Preferably, the aluminum pigment has a solid content of 60-80%, the aluminum particles have an aspect ratio of 30-200, and a particle size of 5-20 μm.

[0010] Preferably, the silane coupling agent is a silane coupling agent containing active sites that can react with hydrophilic or hydrophobic monomers.

[0011] In this invention, the silane coupling agent is selected as a silane coupling agent containing active sites that can react with hydrophilic or hydrophobic monomers. When it is used for aluminum pigment pretreatment, it can graft certain active sites onto the surface of aluminum particles. Then, when it undergoes polymerization reaction with hydrophilic and hydrophobic monomers under initiator conditions, it can attract hydrophilic or hydrophobic monomers to carry out interfacial reactions, so that the resulting amphiphilic polymer coating layer is firmly bonded to the surface of aluminum pigment. This ensures that the floating performance of the obtained aluminum pigment is further improved, while also improving the corrosion resistance.

[0012] Preferably, the epoxy-containing silane coupling agent is γ-glycidoxypropyltrimethoxysilane and / or γ-glycidoxypropyltriethoxysilane; the amino-containing silane coupling agent is γ-aminopropyltrimethoxysilane and / or γ-aminopropyltriethoxysilane.

[0013] Preferably, the alkalinity regulator is at least one of sodium bicarbonate, ammonia, diethanolamine, or ethylenediamine.

[0014] Preferably, the mass ratio of the aluminum pigment to the silane coupling agent is 100:5-15;

[0015] Preferably, the grafting reaction temperature is 40-60℃ and the time is 4-8h.

[0016] Preferably, the hydrophilic monomer includes a tertiary amino alkenyl monomer, and / or the hydrophobic monomer includes an aldehyde alkenyl monomer;

[0017] In this invention, when the hydrophilic monomer includes a tertiary amino-alkenyl monomer, it can undergo a nucleophilic substitution reaction with the aforementioned epoxy-containing silane coupling agent, thereby enabling the hydrophilic monomer containing the tertiary amino-alkenyl monomer to be chemically grafted onto the surface of aluminum particles. Subsequently, when polymerized with other monomers, the amphiphilic polymer can be firmly coated onto the surface of the aluminum particles. When the hydrophobic monomer includes an aldehyde-containing alkenyl monomer, it can undergo a Schiff base condensation reaction with the aforementioned amino-containing silane coupling agent, thereby enabling the hydrophobic monomer containing the aldehyde-containing alkenyl monomer to be chemically grafted onto the surface of aluminum particles. Subsequently, when polymerized with other monomers, the amphiphilic polymer can also be firmly coated onto the surface of the aluminum particles.

[0018] Preferably, the tertiary amino-containing alkenyl monomer is at least one of dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, or dimethylaminopropyl acrylate, and the aldehyde-containing alkenyl monomer is at least one of 4-vinylbenzaldehyde, 3-vinylbenzaldehyde, or 2-vinylbenzaldehyde.

[0019] Preferably, the hydrophilic monomer further includes at least one of polyethylene glycol methacrylate, hydroxyethyl methacrylate, methacrylic acid, acrylamide, maleic anhydride, methacryloyloxyethyl phosphate, acryloyloxyethyl trimethylammonium chloride, or 2-acrylamido-2-methylpropanesulfonic acid; the hydrophobic monomer further includes at least one of methyl methacrylate, methyl acrylate, butyl acrylate, isopropyl methacrylate, lauryl methacrylate, or styrene.

[0020] Preferably, the initiator is at least one selected from azobisisobutyronitrile, azobisisovalerate, benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, potassium persulfate, or ammonium persulfate.

[0021] Preferably, the mass ratio of the pretreated aluminum pigment to the hydrophilic monomer and the hydrophobic monomer is 100:2-8:10-20;

[0022] The polymerization reaction temperature is 70-90℃ and the time is 4-8h.

[0023] Preferably, the reaction solvent used in the grafting reaction and polymerization reaction is an alcohol ether solvent;

[0024] Preferably, the alcohol ether solvent is at least one selected from ethanol, n-propanol, isopropanol, n-butanol, isobutanol, propylene glycol methyl ether, propylene glycol ethyl ether, or ethylene glycol butyl ether.

[0025] The present invention also proposes an aqueous floating aluminum pigment, which is prepared by the above preparation method.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention utilizes a silane coupling agent hydrolyzed under alkaline conditions to coat the surface of aluminum pigment, forming a silane coupling agent interlayer. Subsequently, through polymerization reactions with hydrophilic and hydrophobic monomers under initiator conditions, an amphiphilic polymer layer is in situ coated onto the aluminum pigment surface. The hydrophilic groups in this amphiphilic polymer layer enable the aluminum pigment to disperse in aqueous solvents, while the hydrophobic groups reduce the surface free energy of the aluminum pigment, facilitating its migration from the matrix to the surface and improving its floating properties. Simultaneously, the dense coating layer significantly improves the corrosion resistance of the aluminum pigment. The aluminum pigment obtained by this invention solves the problems of poor floating effect and storage stability of traditional water-based floating aluminum pigments; the aluminum particles are not only protected but also retain the metallic luster of the flake-like aluminum particles to the greatest extent possible. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the water-based floating aluminum pigment described in Embodiment 1 of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the water-based floating aluminum pigment described in Embodiment 2 of the present invention;

[0030] Figure 3 This is a scanning electron microscope image of the water-based floating aluminum pigment described in Embodiment 1 of the present invention;

[0031] Figure 4 This is a scanning electron microscope image of the water-based floating aluminum pigment described in Embodiment 2 of the present invention;

[0032] Figure 5 This is a diagram illustrating the dispersion effect of the water-based floating aluminum pigment described in Embodiment 1 of the present invention. Detailed Implementation

[0033] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0034] Example 1

[0035] A water-based floating aluminum pigment, the preparation method of which includes:

[0036] (1) Oily aluminum pigment (solid content 60wt%, D50 particle size 10μm, aspect ratio 50) was mixed with anhydrous ethanol at a mass ratio of 1:10 and stirred continuously for 0.5h. The solvent oil on the surface of the aluminum pigment was washed off and vacuum dried at 60℃ for 12h. The obtained aluminum pigment was mixed with isopropanol at a mass ratio of 1:10 and heated to 50℃. An isopropanol solution containing 10wt% of the weight of oily aluminum pigment and γ-glycidoxypropyltrimethoxysilane was added dropwise. At the same time, a mixed solution composed of water, ethylenediamine and isopropanol at a mass ratio of 1:1.5:5 was added dropwise. The amount of ethylenediamine added was 10wt% of the mass of γ-glycidoxypropyltrimethoxysilane. After stirring at the temperature for 6h, the mixture was filtered, washed three times, and vacuum dried at 60℃ for 12h to obtain the pretreated aluminum pigment.

[0037] (2) The above-pretreated aluminum pigment was added to isopropanol. Under nitrogen protection, a hydrophilic monomer composed of dimethylaminoethyl acrylate, hydroxyethyl methacrylate and methacrylic acid in a mass ratio of 1:1:0.3 was added. The amount of hydrophilic monomer added was 5 wt% of the mass of the pretreated aluminum pigment. After completion, the temperature was raised to 60°C and stirred for 1 h. Then, a hydrophobic monomer composed of methyl methacrylate and styrene in a mass ratio of 1:1 was added. The amount of hydrophobic monomer added was 15 wt% of the mass of the pretreated aluminum pigment. The temperature was raised to 80°C, and benzoyl peroxide was added dropwise at a total mass of 1 wt% of the hydrophilic and hydrophobic monomers. After stirring and reacting for 6 h, the temperature was lowered to room temperature, washed, and filtered to obtain the water-based floating aluminum pigment.

[0038] Example 2

[0039] A water-based floating aluminum pigment, the preparation method of which includes:

[0040] (1) Oily aluminum pigment (solid content 60wt%, D50 particle size 10μm, aspect ratio 50) was mixed with anhydrous ethanol at a mass ratio of 1:10 and stirred continuously for 0.5h. The solvent oil on the surface of the aluminum pigment was washed off and vacuum dried at 60℃ for 12h. The obtained aluminum pigment was mixed with isopropanol at a mass ratio of 1:10 and heated to 50℃. An isopropanol solution containing 10wt% of the weight of oily aluminum pigment and γ-aminopropyltrimethoxysilane was added dropwise. At the same time, a mixed solution composed of water, ethylenediamine and isopropanol at a mass ratio of 1:1.5:5 was added dropwise. The amount of ethylenediamine added was 10wt% of the mass of γ-aminopropyltrimethoxysilane. After stirring at the temperature for 6h, the mixture was filtered, washed three times, and vacuum dried at 60℃ for 12h to obtain the pretreated aluminum pigment.

[0041] (2) The above-pretreated aluminum pigment was added to isopropanol. Under nitrogen protection, a hydrophobic monomer composed of 4-vinylbenzaldehyde, styrene and butyl acrylate in a mass ratio of 0.2:0.8:1 was added. The amount of hydrophobic monomer added was 15 wt% of the mass of the pretreated aluminum pigment. After completion, the temperature was raised to 60°C and stirred for 1 h. Then, a hydrophilic monomer composed of polyethylene glycol methacrylate (degree of polymerization 10) and 2-acrylamido-2-methylpropanesulfonic acid in a mass ratio of 1:1 was added. The amount of hydrophilic monomer added was 5 wt% of the mass of the pretreated aluminum pigment. The temperature was raised to 80°C, and benzoyl peroxide was added dropwise at a total mass of 1 wt% of the hydrophilic and hydrophobic monomers. After stirring and reacting for 6 h, the temperature was lowered to room temperature, washed, and filtered to obtain the water-based floating aluminum pigment.

[0042] Example 3

[0043] A water-based floating aluminum pigment, the preparation method of which includes:

[0044] (1) Oily aluminum pigment (solid content 60wt%, D50 particle size 10μm, aspect ratio 50) was mixed with anhydrous ethanol at a mass ratio of 1:10 and stirred continuously for 0.5h. The solvent oil on the surface of the aluminum pigment was washed off and vacuum dried at 60℃ for 12h. The obtained aluminum pigment was mixed with isopropanol at a mass ratio of 1:10 and heated to 50℃. An isopropanol solution containing 10wt% of the weight of oily aluminum pigment and γ-glycidoxypropyltrimethoxysilane was added dropwise. At the same time, a mixed solution composed of water, ethylenediamine and isopropanol at a mass ratio of 1:1.5:5 was added dropwise. The amount of ethylenediamine added was 10wt% of the mass of γ-glycidoxypropyltrimethoxysilane. After stirring at the temperature for 6h, the mixture was filtered, washed three times, and vacuum dried at 60℃ for 12h to obtain the pretreated aluminum pigment.

[0045] (2) The above-pretreated aluminum pigment was added to isopropanol. Under nitrogen protection, a hydrophilic monomer composed of acryloyloxyethyltrimethylammonium chloride, hydroxyethyl methacrylate and methacrylic acid in a mass ratio of 1:1:0.3 was added. The amount of hydrophilic monomer added was 5 wt% of the mass of the pretreated aluminum pigment. After completion, the temperature was raised to 60°C and stirred for 1 h. Then, a hydrophobic monomer composed of methyl methacrylate and styrene in a mass ratio of 1:1 was added. The amount of hydrophobic monomer added was 15 wt% of the mass of the pretreated aluminum pigment. The temperature was raised to 80°C, and benzoyl peroxide was added dropwise at a total mass of 1 wt% of the hydrophilic and hydrophobic monomers. After stirring and reacting for 6 h, the temperature was lowered to room temperature, washed, and filtered to obtain the water-based floating aluminum pigment.

[0046] Example 4

[0047] A water-based floating aluminum pigment, the preparation method of which includes:

[0048] (1) Oily aluminum pigment (solid content 60wt%, D50 particle size 10μm, aspect ratio 50) was mixed with anhydrous ethanol at a mass ratio of 1:10 and stirred continuously for 0.5h. The solvent oil on the surface of the aluminum pigment was washed off and vacuum dried at 60℃ for 12h. The obtained aluminum pigment was mixed with isopropanol at a mass ratio of 1:10 and heated to 50℃. An isopropanol solution containing 10wt% of the weight of oily aluminum pigment and γ-aminopropyltrimethoxysilane was added dropwise. At the same time, a mixed solution composed of water, ethylenediamine and isopropanol at a mass ratio of 1:1.5:5 was added dropwise. The amount of ethylenediamine added was 10wt% of the mass of γ-aminopropyltrimethoxysilane. After stirring at the temperature for 6h, the mixture was filtered, washed three times, and vacuum dried at 60℃ for 12h to obtain the pretreated aluminum pigment.

[0049] (2) The above-pretreated aluminum pigment was added to isopropanol. Under nitrogen protection, a hydrophobic monomer composed of styrene and butyl acrylate in a mass ratio of 1:1 was added. The amount of hydrophobic monomer added was 15 wt% of the mass of the pretreated aluminum pigment. After completion, the temperature was raised to 60°C and stirred for 1 h. Then, a hydrophilic monomer composed of polyethylene glycol methacrylate (degree of polymerization 10) and 2-acrylamido-2-methylpropanesulfonic acid in a mass ratio of 1:1 was added. The amount of hydrophilic monomer added was 5 wt% of the mass of the pretreated aluminum pigment. The temperature was raised to 80°C, and benzoyl peroxide was added dropwise at a total mass of 1 wt% of the hydrophilic and hydrophobic monomers. After stirring and reacting for 6 h, the temperature was lowered to room temperature, washed, and filtered to obtain the water-based floating aluminum pigment.

[0050] Comparative Example 1

[0051] A water-based floating aluminum pigment, the preparation method of which includes:

[0052] (1) Oily aluminum pigment (solid content 60wt%, D50 particle size 10μm, aspect ratio 50) was mixed with anhydrous ethanol at a mass ratio of 1:10 and stirred continuously for 0.5h. The solvent oil on the surface of the aluminum pigment was washed off and vacuum dried at 60℃ for 12h. The obtained aluminum pigment was mixed with isopropanol at a mass ratio of 1:10 and heated to 50℃. An isopropanol solution containing 10wt% of the weight of oily aluminum pigment in γ-glycidoxypropyltrimethoxysilane was added dropwise. At the same time, a mixed solution composed of water, ethylenediamine and isopropanol at a mass ratio of 1:1.5:5 was added dropwise. The amount of ethylenediamine added was 10wt% of the mass of γ-glycidoxypropyltrimethoxysilane. After stirring at 50℃ for 6h, the mixture was filtered, washed three times, and vacuum dried at 60℃ for 12h to obtain the pretreated aluminum pigment.

[0053] (2) The above-pretreated aluminum pigment was added to isopropanol. Under nitrogen protection, a hydrophilic monomer composed of acryloyloxyethyltrimethylammonium chloride, hydroxyethyl methacrylate and methacrylic acid in a mass ratio of 1:1:0.3 was added. The amount of hydrophilic monomer added was 20 wt% of the mass of the pretreated aluminum pigment. After completion, the temperature was raised to 80°C, and benzoyl peroxide was added dropwise at 1 wt% of the total mass of the hydrophilic monomer. After stirring and reacting for 6 hours, the temperature was lowered to room temperature, washed, and filtered to obtain the water-based floating aluminum pigment.

[0054] Comparative Example 2

[0055] A water-based floating aluminum pigment, the preparation method of which includes:

[0056] (1) Oily aluminum pigment (solid content 60wt%, D50 particle size 10μm, aspect ratio 50) was mixed with anhydrous ethanol at a mass ratio of 1:10 and stirred continuously for 0.5h. The solvent oil on the surface of the aluminum pigment was washed off and vacuum dried at 60℃ for 12h. The obtained aluminum pigment was mixed with isopropanol at a mass ratio of 1:10 and heated to 50℃. An isopropanol solution containing 10wt% of the weight of oily aluminum pigment and γ-aminopropyltrimethoxysilane was added dropwise. At the same time, a mixed solution composed of water, ethylenediamine and isopropanol at a mass ratio of 1:1.5:5 was added dropwise. The amount of ethylenediamine added was 10wt% of the mass of γ-aminopropyltrimethoxysilane. After stirring at the temperature for 6h, the mixture was filtered, washed three times, and vacuum dried at 60℃ for 12h to obtain the pretreated aluminum pigment.

[0057] (2) The above-pretreated aluminum pigment was added to isopropanol. Under nitrogen protection, a hydrophobic monomer composed of styrene and butyl acrylate in a mass ratio of 1:1 was added. The amount of hydrophobic monomer added was 20 wt% of the mass of the pretreated aluminum pigment. After completion, the temperature was raised to 80°C, and benzoyl peroxide was added dropwise at 1 wt% of the total mass of the hydrophobic monomer. After stirring and reacting for 6 hours, the temperature was lowered to room temperature, washed, and filtered to obtain the water-based floating aluminum pigment.

[0058] Figure 1 , 2 These are schematic diagrams of the structures of the water-based floating aluminum pigments described in Examples 1 and 2, respectively. Figure 1 , 2 As shown, the surface of the water-based floating aluminum pigments described in Examples 1 and 2 is chemically grafted with amphiphilic polymers.

[0059] Figure 3 , 4 The scanning electron microscope (SEM) images of the water-based floating aluminum pigments described in Examples 1 and 2 are shown below. Figure 3 , 4 As shown, the water-based floating aluminum pigments described in Examples 1 and 2 have a flake-like structure with a coating layer on the surface.

[0060] Figure 5 The image shows the floating effect of the water-based floating aluminum pigment described in Example 1 in isopropanol (aluminum pigment to solvent mass ratio of 1:10). Figure 5 As shown, the water-based floating aluminum pigment described in Example 1 has an excellent mirror effect.

[0061] Performance testing:

[0062] According to the "Chemical Industry Standard of the People's Republic of China - Aluminum Pigments for Coatings Part 5: Waterborne Aluminum Powder Paste: HG / T2456.5-2016", the water dispersibility of the aluminum pigments obtained in the examples and comparative examples was tested. 0.1 g of the aluminum pigments obtained in the examples and comparative examples were added to 50 mL of 0.1 mol / L HCl and 0.01 mol / L NaOH, respectively. The generated H2 was collected by water displacement gas collection method, and the amount of hydrogen evolution within 48 h was measured.

[0063] In an acrylic square tank with dimensions of 10cm in length, width, and height, aluminum pigment obtained in the examples and comparative examples is weighed out in small amounts and repeatedly. The pigment is then sprinkled into the tank containing 8cm of water and gently scraped to disperse the flake-like aluminum pigment completely on the water surface. When the amount of aluminum pigment added is sufficient to form a dense, continuous, and uniform thin layer that is evenly and continuously distributed in the water tank without piling up, leaks, or wrinkles, the total amount of aluminum pigment used at this point is recorded. The area of ​​the water surface covered by a unit mass of aluminum pigment can then be calculated. The average value is taken from three measurements.

[0064] The gloss of the aluminum pigments obtained in the examples and comparative examples was tested using a gloss meter. Specifically, the aluminum pigments were added to commercially available water-based polyurethane (mass ratio of 1:10), dispersed evenly, and then sprayed onto a substrate. The gloss of the aluminum pigment coating was then measured using a gloss meter at an angle of 60°.

[0065] The results are shown in Table 1 below:

[0066] Table 1. Performance test results of aluminum pigments obtained in the examples and comparative examples.

[0067]

[0068] As can be seen from Table 1, compared with existing oil-based aluminum pigments, the water-based floating aluminum pigment prepared by the present invention has good floating performance in water-based matrices, excellent acid corrosion resistance, and still maintains a high gloss.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a water-based floating aluminum pigment, characterized in that, Includes the following steps: S1. Grafting reaction of aluminum pigment and silane coupling agent under alkaline regulator, grafting silane coupling agent onto the surface of aluminum particles to obtain pretreated aluminum pigment. S2. The pretreated aluminum pigment is polymerized with hydrophilic and hydrophobic monomers under initiator conditions to coat the surface of aluminum particles with amphiphilic polymers, thereby obtaining the water-based floating aluminum pigment. The silane coupling agent is an epoxy-containing silane coupling agent and / or an amino-containing silane coupling agent; The epoxy-containing silane coupling agent is γ-glycidoxypropyltrimethoxysilane and / or γ-glycidoxypropyltriethoxysilane; the amino-containing silane coupling agent is γ-aminopropyltrimethoxysilane and / or γ-aminopropyltriethoxysilane. The hydrophilic monomer includes a tertiary amino alkenyl monomer, and / or the hydrophobic monomer includes an aldehyde alkenyl monomer; The tertiary amino-alkenyl monomer is at least one of dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, or dimethylaminopropyl acrylate, and the aldehyde-alkenyl monomer is at least one of 4-vinylbenzaldehyde, 3-vinylbenzaldehyde, or 2-vinylbenzaldehyde. The hydrophilic monomer further includes at least one of polyethylene glycol methacrylate, hydroxyethyl methacrylate, methacrylic acid, acrylamide, maleic anhydride, methacryloyloxyethyl phosphate, acryloyloxyethyl trimethylammonium chloride, or 2-acrylamido-2-methylpropanesulfonic acid; the hydrophobic monomer further includes at least one of methyl methacrylate, methyl acrylate, butyl acrylate, isopropyl methacrylate, lauryl methacrylate, or styrene. The initiator is at least one of azobisisobutyronitrile, azobisisovalerate, benzoyl peroxide, diisopropylbenzene peroxide, methyl ethyl ketone peroxide, potassium persulfate, or ammonium persulfate.

2. The method for preparing water-based floating aluminum pigment according to claim 1, characterized in that, The aluminum pigment has a solid content of 60-80%, the aluminum particles have an aspect ratio of 30-200, and a particle size of 5-20 μm.

3. The method for preparing water-based floating aluminum pigment according to claim 1 or 2, characterized in that, The mass ratio of the aluminum pigment to the silane coupling agent is 100:5-15; the grafting reaction temperature is 40-60℃ and the time is 4-8h.

4. The method for preparing water-based floating aluminum pigment according to claim 1 or 2, characterized in that, The mass ratio of the pretreated aluminum pigment to the hydrophilic monomer and the hydrophobic monomer is 100:2-8:10-20; The polymerization reaction temperature is 70-90℃ and the time is 4-8h.

5. The method for preparing water-based floating aluminum pigment according to claim 1 or 2, characterized in that, The reaction solvents used in the grafting and polymerization reactions are alcohol ether solvents; The alcohol ether solvent is at least one of ethanol, n-propanol, isopropanol, n-butanol, isobutanol, propylene glycol methyl ether, propylene glycol ethyl ether, or ethylene glycol butyl ether.

6. A water-based floating aluminum pigment, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.

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