Aluminum pigment used in UV coatings and preparation method thereof

Abstract

The invention discloses a kind of aluminum pigment applied to UV coating, it is made up of the raw materials of following weight parts:20 30 parts of pigment body, 40 75 parts of reaction system solvent, 0.01 0.2 parts of polymerization inhibitor, 0.2 0.5 parts of acid treatment agent, 1.5 4.0 parts of active passivating agent and 0.3 1.0 parts of dispersant.The present invention also provides the preparation method of above-mentioned aluminum pigment.The present invention adopts active passivating agent to process aluminum pigment surface, so that it can participate in the polymerization reaction of coating overall during UV curing, improve paint film performance, meanwhile, select suitable active diluent as main solvent, on the basis of retaining n-butyl acrylate toughness and aluminum pigment compatibility, introduce dipropylene glycol diacrylate, improve crosslinking density and cure rate by functional group synergistic effect, so that it can directly participate in the curing process of UV coating without pre-baking, while reducing the VOC emissions in construction process, reducing construction energy consumption, reducing construction time, also do not affect the metallic texture and the corrosion resistance of aluminum pigment.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical materials, and more particularly to an aluminum pigment used in UV coatings and a preparation method thereof. Background Art

[0002] UV coatings are ultraviolet-curing coatings that rapidly cure to form a film under ultraviolet light. UV coatings have seen rapid development in recent years, gaining widespread application across various coatings industries due to their low VOC emissions, fast cure speed, high film properties, high stability, and low energy consumption. However, since their primary components are acrylic acid, acrylate monomers, and their prepolymers, they often have high acid values. In these cases, aluminum pigments must possess high acid stability and good system compatibility to maintain the long-term stability of the resin system before curing. Furthermore, depending on the application scenario, the cured paint film must exhibit strong corrosion resistance. For aluminum pigments, achieving this high corrosion resistance often requires a thicker coating, which can compromise the pigment's hue. Furthermore, since almost all commercially available aluminum pigment pastes contain a high proportion of solvents that are incompatible with curing, application requires a two-step pre-baking and curing process, which generates certain VOC emissions and significantly increases application energy consumption and time. This, in turn, limits the application of aluminum pigments in UV coatings.

[0003] Most commercially available passivated aluminum pigments are water-based, primarily using alcohols and ethers as their primary solvents, with a smaller number using water as the solvent. These aluminum pigments cannot directly cure to form films when used in UV coatings. Pre-baking to remove the solvent is typically required before UV curing. This process increases VOC emissions, energy consumption, and application time. Furthermore, because UV coatings contain many reactive monomers and oligomers, they are prone to localized self-aggregation during the baking process, affecting film uniformity and, consequently, film performance. Furthermore, conventional passivated and silica-based aluminum pigments lack surface active structures that participate in the UV curing reaction, relying solely on simple bonding methods such as polar groups. This significantly reduces the aluminum pigment's compatibility and corrosion resistance, preventing it from fully demonstrating the excellent film properties of UV coatings. While resin-encapsulated aluminum pigments offer excellent resin bonding and corrosion resistance, they lack the ability to exhibit high brightness. Therefore, we propose an aluminum pigment for UV coatings and a method for its preparation. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, one of the objectives of the present invention is to provide an aluminum pigment for use in UV coatings to solve the technical problems that most existing water-based aluminum pigments cannot be directly cured into films when used in UV coatings, resulting in increased VOC emissions and energy consumption during the construction process, and conventional passivated and silica-based aluminum pigments participate in the UV curing reaction due to their inactive surface structures, which in turn leads to poor paint film performance.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] An aluminum pigment for UV coatings is composed of the following raw materials in parts by weight: 20-30 parts of a pigment main body, 40-75 parts of a reaction system solvent, 0.01-0.2 parts of a polymerization inhibitor, 0.2-0.5 parts of an acid treatment agent, 1.5-4.0 parts of an active passivator, and 0.3-1.0 parts of a dispersant; wherein the pigment main body is an oily flaky ball-milled aluminum pigment; the reaction system solvent includes an acrylate active diluent; the acrylate active diluent is a compound system of n-butyl acrylate (BA) and dipropylene glycol diacrylate (DPGDA); in the compound system, n-butyl acrylate accounts for 80-85% and dipropylene glycol diacrylate accounts for 15-20%.

[0007] The present invention adopts an active passivating agent to treat the surface of the aluminum pigment so that the aluminum pigment can participate in the polymerization reaction of the entire coating during UV curing, so as to completely become an integral part of the coating and improve the performance of the paint film. At the same time, by selecting a suitable active diluent to replace solvents such as alcohols, ethers and water as the main solvent of the water-based aluminum pigment, dipropylene glycol diacrylate is introduced while retaining the flexibility of n-butyl acrylate and the compatibility of the aluminum pigment. The crosslinking density and curing rate are increased through the synergistic effect of functional groups, so that the aluminum pigment can directly participate in the curing process of the UV coating without pre-baking. VOC emissions during the construction process are reduced, construction energy consumption is reduced, and construction time is shortened, while the metallic texture and corrosion resistance of the aluminum pigment are not affected.

[0008] Preferably, the solid content of the oily flaky ball-milled aluminum pigment is controlled at 70-80% to reduce the proportion of solvent, the solvent is one or more of D50, D70, 100#, and 150#, the particle size D50 is 11-18 microns, and the particle size span is 0.8-1.0.

[0009] Preferably, the polymerization inhibitor is hydroquinone monomethyl ether. The polymerization inhibitor is added to prevent the active diluent as a solvent from undergoing polymerization during the passivation process.

[0010] Preferably, the acid treatment agent is acrylic acid. Since the surface activity of oily flaky aluminum pigment is low, it needs to be acidified before the reaction to increase the active sites on its surface to help the reaction, so an acidic active substance is selected for pretreatment.

[0011] Preferably, the active deactivator is one or more of methacryloyloxyethyl phosphate, 2-hydroxyethyl methacrylate phosphate, ethylene glycol methacrylate phosphate, methacryloyloxyethyl succinate monoester, and methacryloyloxyethyl maleate monoester.

[0012] Preferably, the dispersant is propylene glycol.

[0013] A second object of the present invention is to provide a method for preparing the above-mentioned aluminum pigment for UV coating, comprising the following steps:

[0014] (1) According to the weight ratio, the pigment body is put into a stainless steel stirred reactor, and then the pigment body is added. The temperature of the reactor is set to 45°C, stirring and heating are started, and after the heating is completed, an acid treatment agent is added thereto, and the temperature is kept and stirred for a period of time to increase the active sites on the surface of the aluminum pigment;

[0015] (2) After the acid treatment is completed, a portion of the active passivation agent prepared in advance is added to the reactor, and the mixture is stirred at this temperature for 30 minutes. Then, the remaining portion of the active passivation agent is added to the reactor, and the mixture is stirred at this temperature for a period of time, so that the phosphate ester can fully passivate the aluminum sheet;

[0016] (3) After the stirring is completed, cooling is started. When the cooling temperature is lower than 30°C, the reaction slurry is pumped into a filter press using a peristaltic pump for filter pressing. The filter cake obtained by the filter pressing is then placed in an industrial kneading mixer, a dispersant is added, and the solid content is adjusted to 25-40% using the reaction system solvent to obtain a finished product.

[0017] Furthermore, in step (1), the maximum temperature of the heating is 50° C. The heating temperature should not be higher than 50° C. in order to prevent the polymerization inhibitor from failing and causing the butyl acrylate to self-polymerize.

[0018] Furthermore, in step (1), the heat preservation and stirring time is 3-6 hours, and the stirring rate is 500-800 rpm. The heat preservation and stirring time cannot be less than 3 hours to ensure sufficient acid treatment.

[0019] Furthermore, in step (2), the heat preservation and stirring time is 6-8 hours, and the stirring rate is 500-800 rpm. The total heat preservation and stirring time cannot be less than 6 hours to ensure that the phosphate ester fully passivates the aluminum sheet.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention uses an active passivating agent to treat the surface of the aluminum pigment so that it can participate in the polymerization reaction of the entire coating during the UV curing process, so as to achieve complete integration with the coating and improve the performance of the paint film. At the same time, by selecting a suitable active diluent instead of solvents such as alcohols, ethers and water as the main solvent of the water-based aluminum pigment, dipropylene glycol diacrylate is introduced while retaining the flexibility of n-butyl acrylate and the compatibility of the aluminum pigment. The crosslinking density and curing rate are improved through the synergistic effect of functional groups, so that it can directly participate in the curing process of the UV coating without pre-baking, reducing VOC emissions during the construction process, reducing construction energy consumption, and shortening construction time without affecting the metallic texture and corrosion resistance of the aluminum pigment.

[0022] 2. The present invention uses phosphate passivation to treat aluminum pigments. The resulting product has very little solvent content and can be directly cured into a film without pre-baking, which greatly reduces VOC emissions during construction, reduces construction energy consumption, and shortens construction time. Compared with conventional water-based silica-coated and resin-coated aluminum pigments, it has more excellent metallic texture and acid and alkali resistance, and has excellent paint film performance.

[0023] 3. Since the active diluent is the solvent of the reaction system and does not participate in the passivation process of the aluminum pigment, it can be selected and changed according to different UV resin systems, with a higher degree of matching. Moreover, due to the control of a lower solid content, there is no need to dilute again in actual applications, and almost all of the active diluent used can be utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This figure shows the results of immersion tests of various products in a 5% by mass NaOH aqueous solution in the embodiments of the present invention. From left to right in the figure, there are commercially available passivated aluminum paste, commercially available silica-coated aluminum paste, commercially available resin-coated aluminum paste, and the finished aluminum pigment prepared in the present invention.

[0025] Figure 2 This figure shows the results of immersion tests of various products in an embodiment of the present invention using a 5% mass fraction HCl aqueous solution. In the figure, from left to right, commercially available passivation aluminum paste, commercially available silica-coated aluminum paste, commercially available resin-coated aluminum paste, and the finished aluminum pigment prepared by the present invention are shown;

[0026] Figure 3 This is a comparison chart of the whiteness of the commercially available silica-coated aluminum paste and the finished aluminum pigment prepared by the present invention in a UV system scraper test. In the figure, the left area is coated with the commercially available silica-coated aluminum paste, and the right area is coated with the finished aluminum pigment prepared by the present invention.

[0027] Figure 4This is a comparison chart of the whiteness of the commercially available passivation aluminum-silver paste and the finished aluminum pigment prepared by the present invention in a UV system scraper test in an embodiment of the present invention. In the figure, the left area is coated with the commercially available passivation aluminum-silver paste, and the right area is coated with the finished aluminum pigment prepared by the present invention;

[0028] Figure 5 This is a UV system scraper test whiteness comparison chart of the commercially available resin-coated aluminum silver paste and the finished aluminum pigment prepared by the present invention in an embodiment of the present invention. In the figure, the left area is coated with the commercially available resin-coated aluminum silver paste, and the right area is coated with the finished aluminum pigment prepared by the present invention. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] Unless otherwise specified, the experimental materials and reagents used in the following examples can be obtained from commercial channels. If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0031] An aluminum pigment used in UV coatings is prepared by phosphate passivation and is made from the following raw materials in parts by weight:

[0032] 20-30 parts of pigment main body, 40-75 parts of reaction system solvent, 0.01-0.2 parts of polymerization inhibitor, 0.2-0.5 parts of acid treatment agent, 1.5-4.0 parts of active passivator and 0.3-1.0 parts of dispersant;

[0033] Among them, the main pigment is oily flake ball-milled aluminum pigment;

[0034] The reaction system solvent includes an acrylate active diluent; the acrylate active diluent is a compound system of n-butyl acrylate (BA) and dipropylene glycol diacrylate (DPGDA); in the compound system, n-butyl acrylate accounts for 80-85% and dipropylene glycol diacrylate accounts for 15-20%.

[0035] Among them, the solid content of the oily flaky ball-milled aluminum pigment is controlled at 70-80% to reduce the proportion of solvent, the solvent is one or more of D50, D70, 100#, and 150#, the particle size D50 is 11-18 microns, and the particle size span is 0.8-1.0.

[0036] The polymerization inhibitor is hydroquinone monomethyl ether. The addition of the polymerization inhibitor is to prevent the active diluent as a solvent from polymerizing during the passivation process.

[0037] Since the surface activity of oily flaky aluminum pigment is low, it needs to be acidified before the reaction to increase the active sites on its surface to help the reaction, so an acidic active substance is selected for pretreatment. Therefore, the present invention uses acrylic acid as the acid treatment agent.

[0038] The active passivator is one or more of methacryloyloxyethyl phosphate, 2-hydroxyethyl methacrylate phosphate, ethylene glycol methacrylate phosphate, methacryloyloxyethyl succinate monoester, and methacryloyloxyethyl maleate monoester.

[0039] The dispersant is propylene glycol.

[0040] Example 1

[0041] This embodiment provides a method for preparing an aluminum pigment for use in UV coatings, comprising the following steps:

[0042] (1) 50 kg of aluminum pigment was placed in a stainless steel stirred reactor, followed by 80 kg of n-butyl acrylate and 20 kg of dipropylene glycol diacrylate, and 0.1 kg of hydroquinone monomethyl ether. The temperature of the reactor was set to 45°C, stirring was started, and the temperature was raised to 50°C. After the temperature was raised, 0.5 kg of acrylic acid was added, and the mixture was stirred at this temperature for 6 hours at a stirring rate of 500 rpm.

[0043] (2) Prepare 2.5 kg of 2-hydroxyethyl methacrylate phosphate and 1.5 kg of ethylene glycol methacrylate phosphate in advance. After the acid treatment is completed, add the prepared 2-hydroxyethyl methacrylate phosphate directly to the reactor and stir at this temperature for 30 minutes. Then, add the ethylene glycol methacrylate phosphate to the reactor and stir at this temperature for 8 hours at a stirring rate of 500 rpm.

[0044] (3) After the stirring is completed, cooling is started. When the cooling temperature is lower than 30° C., the reaction slurry is pumped into a filter press using a peristaltic pump for filter pressing. The filter cake obtained by the filter pressing is placed in an industrial kneading mixer, 0.9 kg of dispersant is added, and the solid content is adjusted to 25-40% using n-butyl acrylate to obtain a finished product.

[0045] Example 2

[0046] This embodiment provides a method for preparing an aluminum pigment for use in UV coatings, comprising the following steps:

[0047] (1) 60 kg of aluminum pigment was placed in a stainless steel stirred reactor, followed by 80 kg of n-butyl acrylate and 20 kg of dipropylene glycol diacrylate, and 0.2 kg of hydroquinone monomethyl ether. The temperature of the reactor was set to 45°C, stirring was started, and the temperature was raised to 50°C. After the temperature was raised, 0.8 kg of acrylic acid was added, and the mixture was stirred at this temperature for 6 hours at a stirring rate of 500 rpm.

[0048] (2) Prepare 5 kg of 2-hydroxyethyl methacrylate phosphate and 1.5 kg of ethylene glycol methacrylate phosphate in advance. After the acid treatment is completed, add the prepared 2-hydroxyethyl methacrylate phosphate directly into the reactor, keep warm and stir for 30 minutes, then add ethylene glycol methacrylate phosphate into the reactor, keep warm and stir for 8 hours, and the stirring rate is 500 rpm.

[0049] (3) After the stirring is completed, cooling is started. When the cooling temperature is lower than 30° C., the reaction slurry is pumped into a filter press using a peristaltic pump for filter pressing. The filter cake obtained by the filter pressing is placed in an industrial kneading mixer, 1.5 kg of dispersant is added, and the solid content is adjusted to 25-40% using n-butyl acrylate to obtain a finished product.

[0050] Example 3

[0051] This embodiment provides a method for preparing an aluminum pigment for use in UV coatings, comprising the following steps:

[0052] (1) 70 kg of aluminum pigment was placed in a stainless steel stirred reactor, followed by 80 kg of n-butyl acrylate and 20 kg of dipropylene glycol diacrylate, and 0.35 kg of hydroquinone monomethyl ether. The reactor temperature was set to 45°C, stirred, and heated to 50°C. After heating, 1.1 kg of acrylic acid was added, and the mixture was stirred at this temperature for 6 h at a stirring rate of 500 rpm.

[0053] (2) Prepare 7 kg of 2-hydroxyethyl methacrylate phosphate and 2.1 kg of ethylene glycol methacrylate phosphate in advance. After the acid treatment is completed, add the prepared 2-hydroxyethyl methacrylate phosphate directly to the reactor and stir at this temperature for 30 minutes. Then, add the ethylene glycol methacrylate phosphate to the reactor and stir at this temperature for 8 hours at a stirring rate of 500 rpm.

[0054] (3) After the stirring is completed, cooling is started. When the cooling temperature is lower than 30° C., the reaction slurry is pumped into a filter press using a peristaltic pump for filter pressing. The filter cake obtained by the filter pressing is placed in an industrial kneading mixer, 2.1 kg of dispersant is added, and the solid content is adjusted to 25-40% using n-butyl acrylate to obtain a finished product.

[0055] Comparative Example

[0056] This comparative example provides a method for preparing an aluminum pigment. The preparation method is substantially the same as that of Example 2, with the only difference being that the reaction system solvent of this comparative example uses only n-butyl acrylate (BA).

[0057] 1. The performance of the finished pigment prepared in the comparative example was compared with that of the finished aluminum pigment prepared in Example 2. The test results are shown in Table 1.

[0058] Table 1 Pigment performance test comparison

[0059] Group Active diluent composition <![CDATA[Touch drying time (UV curing, 800 mW / cm 2 )]]> Appearance of paint film after immersion in 5% NaOH for 48 hours Comparative Example 100% BA 65s Slightly whitish, bubbling Example 2 BA:DPGDA=8:2 35s No significant changes

[0060] According to the results in Table 1, it can be seen that the curing rate of the compound system is increased by 46%, and the alkali resistance is better than that of single BA.

[0061] 2. The acid and alkali resistance of the paint film was tested by respectively testing the commercially available passivated aluminum paste, silica-coated aluminum paste and resin-coated aluminum paste of the same particle size (15 μm) and the finished aluminum pigment prepared in Example 2 (silver paste content of 8%; soaking for 48 hours). The results are as follows: Figure 1 and Figure 2 As shown, Figure 1 The results of the immersion test using a 5% mass fraction NaOH aqueous solution are shown in the figure. Figure 2 These are the test results using a 5% mass fraction HCl aqueous solution. From left to right in the figure are commercially available passivated aluminum-silver paste, commercially available silica-coated aluminum-silver paste, commercially available resin-coated aluminum-silver paste, and the finished aluminum pigment prepared by the present invention.

[0062] according to Figure 1 and Figure 2 The results show that the alkali resistance of the present invention in the UV paint film is significantly better than that of conventional passivation and silica-coated aluminum pigments; the acid resistance of the paint film is consistent with that of passivation and resin-coated aluminum silver paste, and is better than that of commercially available silica-coated aluminum pigments.

[0063] 3. The commercially available passivated aluminum paste, silica-coated aluminum paste, and the aluminum pigment prepared in the present invention with the same particle size (15 μm) were subjected to an accelerated hydrogen evolution test in a water-based UV coating system (silver paste content was 8%, total mass was 270 g, and the test was conducted at a constant temperature of 50°C for 20 days (D); since resin-coated aluminum pigments are generally used in oil-based systems, no comparison was made in the water-based UV system). The results are shown in Table 2.

[0064] Table 2 Hydrogen evolution acceleration test results of waterborne UV coating systems of commercially available passivated aluminum paste, silica-coated aluminum paste and aluminum pigment products prepared in the present invention of the same particle size (15 μm) (gas release unit: ml)

[0065]

[0066] According to the results in Table 2, it can be seen that the hydrogen evolution limit for conventional plastic paint systems on the market is a gas evolution volume of less than 20 ml in 7 days. From the above results, it can be seen that the stability of commercially available silica-coated products and passivated products in water-based UV coatings is poor, and it is difficult to meet the long-term storage requirements of the market water-based UV resin system. The storage stability of the finished aluminum pigment prepared by the present invention is significantly better than that of commercially available products, and has better stability.

[0067] 4. A UV system scraper test was performed on commercially available passivated aluminum paste, silica-coated aluminum paste, resin-coated aluminum paste and the finished aluminum pigment prepared in Example 2 of the present invention with the same particle size (15 μm) (silver paste content is 10%; UV resin system, 50 μm wet film preparation device, unit: mg / kg). The specific method is as follows: a comparative test was performed on the same test plate, and the above-mentioned commercially available aluminum pigment (passivated aluminum paste, silica-coated aluminum paste or resin-coated aluminum paste) was dripped on the left side of the test plate, and the finished aluminum pigment prepared by the present invention was dripped on the right side, and then evenly scraped from top to bottom with a scraper, and whiteness comparison and brightness comparison were performed after drying; since conventional aluminum pigments need to be diluted before use, the dilution solvent used was the same active diluent used in the present invention. In addition, in order to make the color comparison more intuitive, this test added aluminum pigment in an amount higher than the normal market usage, and extended the curing time to ensure complete curing.

[0068] Table 3 Comparison results of UV system scraper test

[0069]

[0070]

[0071] Note: L* represents lightness, ranging from 0 (black) to 100 (white), and is used to describe the brightness of the color; a * Represents the color components from green to red; b * Represents color components from blue to yellow; C * It refers to the chroma of color, also called saturation; h represents the hue angle; Si represents the reflectivity and transmittance of the coating; Sa represents the average surface roughness at different angles; G represents glossiness.

[0072] according to Figure 3-5From the hue comparison and the results in Table 3, it can be seen that the finished aluminum pigment prepared by the present invention has a hue equivalent to that of conventional passivated products, and its whiteness is significantly better than that of commercially available passivated aluminum-silver paste, silica-coated aluminum-silver paste, and resin-coated aluminum-silver paste; the brightness of the finished aluminum pigment prepared by the present invention is significantly better than that of commercially available silica-coated and resin-coated aluminum pigments.

[0073] Based on the above conclusions, the present invention uses an active passivator to treat the surface of the aluminum pigment, so that it can participate in the overall polymerization reaction of the coating during the UV curing process, so as to achieve complete integration with the coating and improve the performance of the paint film. At the same time, by selecting a suitable active diluent instead of solvents such as alcohols, ethers and water as the main solvent of the water-based aluminum pigment, while retaining the flexibility of n-butyl acrylate and the compatibility of the aluminum pigment, dipropylene glycol diacrylate is introduced, and the crosslinking density and curing rate are improved through the synergistic effect of functional groups, so that it can directly participate in the curing process of the UV coating without pre-baking, while reducing VOC emissions during the construction process, reducing construction energy consumption, and shortening construction time, without affecting the metallic texture and corrosion resistance of the aluminum pigment.

[0074] The embodiments disclosed in the present invention are preferred embodiments, but are not limited to them. Ordinary technicians in this field can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. As long as they do not deviate from the spirit of the present invention, they are all within the scope of protection of the present invention.

Claims

1. An aluminum pigment used in UV coatings, characterized in that: It is composed of the following raw materials in parts by weight: 20-30 parts of pigment main body, 40-75 parts of reaction system solvent, 0.01-0.2 parts of polymerization inhibitor, 0.2-0.5 parts of acid treatment agent, 1.5-4.0 parts of active passivator and 0.3-1.0 parts of dispersant; Wherein, the pigment body is oily flaky ball-milled aluminum pigment; The reaction system solvent includes an acrylic acid ester reactive diluent; The acrylic ester active diluent is a compound system of n-butyl acrylate and dipropylene glycol diacrylate; in the compound system, n-butyl acrylate accounts for 80-85% and dipropylene glycol diacrylate accounts for 15-20%.

2. The aluminum pigment for UV coating according to claim 1, characterized in that: The solid content of the oily flaky ball-milled aluminum pigment is controlled at 70-80% to reduce the proportion of the solvent. The solvent is one or more of D50, D70, 100#, and 150#. The particle size D50 is 11-18 microns, and the particle size span is 0.8-1.

0.

3. The aluminum pigment for UV coating according to claim 1, characterized in that: The polymerization inhibitor is hydroquinone monomethyl ether.

4. The aluminum pigment for UV coating according to claim 1, characterized in that: The acid treatment agent is acrylic acid.

5. The aluminum pigment for UV coating according to claim 1, characterized in that: The active passivator is one or more of methacryloyloxyethyl phosphate, 2-hydroxyethyl methacrylate phosphate, ethylene glycol methacrylate phosphate, methacryloyloxyethyl succinate monoester, and methacryloyloxyethyl maleate monoester.

6. The aluminum pigment for UV coating according to claim 1, characterized in that: The dispersant is propylene glycol.

7. A method for preparing an aluminum pigment for UV coatings according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) According to the weight ratio, the pigment body is put into a stainless steel stirred reactor, and then the reaction system solvent and polymerization inhibitor are added. The temperature of the reactor is set to 45°C, stirring and heating are started, and after heating is completed, the acid treatment agent is added thereto, and the temperature is kept and stirred for a period of time; (2) After the acid treatment is completed, a portion of the active passivation agent prepared in advance is added to the reactor, and the mixture is stirred at this temperature for 30 minutes. Then, the remaining portion of the active passivation agent is added to the reactor, and the mixture is stirred at this temperature for a period of time to allow the phosphate to fully passivate the aluminum sheet. (3) After the stirring is completed, cooling is started. When the cooling temperature is lower than 30°C, the reaction slurry is pumped into a filter press using a peristaltic pump for filter pressing. The filter cake obtained by the filter pressing is then placed in an industrial kneading mixer, a dispersant is added, and the solid content is adjusted to 25-40% using the reaction system solvent to obtain a finished product.

8. The method for preparing an aluminum pigment for UV coating according to claim 7, wherein: In step (1), the maximum temperature of the heating is 50°C.

9. The method for preparing an aluminum pigment for UV coating according to claim 7, wherein: In step (1), the heat preservation and stirring time is 3-6 hours, and the stirring rate is 500-800 rpm.

10. The method for preparing aluminum pigment for UV coating according to claim 7, characterized in that: In step (2), the heat preservation and stirring time is 6-8 hours, and the stirring rate is 500-800 rpm.

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