Preparation of a colored metallic, velvet effect powder coating

Abstract

The application discloses a kind of preparation of color metal texture soft grain effect powder coating, belong to powder coating technical field.The coating with bisphenol A type epoxy resin, carboxyl polyester resin as matrix, and contain specially made ion liquid modified metal pigment.The characteristics of the pigment are that by polymerizable ionic liquid in-situ polymerization of methyl methacrylate and coloring monomer is mediated on the surface of aluminum powder, and color polymer coating is formed.The application adopts base material melt extrusion+effect pigment bonding composite process to prepare coating;Through chemical grafting mode, simultaneously solve the technical problems such as metal pigment easy oxidation, color and metal sense separation, texture control difficult, the obtained coating has the comprehensive advantages such as color gorgeous integration, metal texture lasting, soft grain effect delicate and uniform, strong adhesion, suitable for high-end decoration field.

Description

Technical Field

[0001] This invention relates to the field of powder coating technology, and in particular to the preparation of a colored metallic textured powder coating. Background Technology

[0002] Powder coatings, as an environmentally friendly type of coating, are widely used for the decoration and protection of metal surfaces due to their advantages such as being solvent-free, having high utilization rates, and exhibiting excellent performance. Among them, powder coatings with metallic textures and special patterns (such as cotton or hammered textures) are highly favored by the market due to their elegant appearance and good hiding properties.

[0003] First, in achieving a metallic texture, current methods primarily rely on physically mixing and adding flake-shaped metallic pigments (such as aluminum powder). This method has inherent drawbacks: metallic pigments are easily oxidized and lose their gloss during processing and storage, and physical mixing makes it difficult to ensure uniform dispersion and strong bonding within the resin matrix, easily leading to problems such as color difference, streaks, or short-lasting metallic effect in the coating. Second, in achieving a colored metallic effect, the traditional method is to simply blend colored pigments with metallic pigments. This method causes the color and metallic optical effect to separate in the coating, lacking a sense of unity and layering. Furthermore, due to the differences in the physicochemical properties of different pigments, separation easily occurs during processing or use, causing color difference or unevenness. Third, in achieving textured (such as cotton-like) effects, existing technologies heavily rely on external texture additives (such as hammer finish agents). The texture formation effect of this method is extremely sensitive to the type and amount of additives and process conditions, resulting in a narrow process window, poor repeatability, and a tendency to cause coating defects such as pinholes due to compatibility issues.

[0004] More importantly, the technical requirements of metallic pigments—stability, color integration with metal, and texture controllability—are mutually restrictive. For example, surface treatments to improve the stability of metallic pigments may affect their optical effects and compatibility with resins; complex processing to achieve color integration may exacerbate the oxidation of metallic pigments and damage texture formation. Existing technologies lack a systematic solution that can synergistically address these multiple problems, often resorting to compromises, resulting in coatings whose overall decorative effect and durability fail to meet the demands of high-end applications.

[0005] Therefore, developing a new type of powder coating that can simultaneously solve many problems such as the stability of metallic pigments, the integration of color and metal, and the controllability of texture has become a technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and to propose a method for preparing colored metallic textured powder coatings.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A colored metallic textured powder coating, comprising the following components by weight: Bisphenol A type epoxy resin: 30-40 parts Carboxylated polyester resin: 30-40 parts Ionic liquid modified metallic pigments: 10-20 parts Hardener: 4-7 parts Leveling agent: 0.8-1.5 parts Benzoin: 0.3-0.6 parts Precipitated barium sulfate: 15-25 parts Cotton-texturing agent: 0.5-1.5 parts.

[0008] The ionic liquid-modified metallic pigment is prepared by the following method: 1) Pretreatment of metallic pigments: Dissolve a polymerizable ionic liquid in a low-boiling-point organic solvent and stir at 200-300 rpm for 20-40 minutes at room temperature until the ionic liquid is completely dissolved, forming a homogeneous and clear modified solution with a concentration of 1-5 wt%. Add the flake-shaped metallic pigment to the modified solution and stir continuously at 300-400 rpm for 30-60 minutes to ensure that the metallic pigment is fully dispersed in the modified solution and forms a uniform suspension. After that, introduce high-purity inert gas into the reaction system for 20-30 minutes to remove oxygen from the system. 2) Preparation of ionic liquid modified metallic pigments: Under continuous nitrogen purging and stirring, a mixture of methyl methacrylate, a coloring monomer containing polymerizable double bonds, and the initiator azobisisobutyronitrile (AIBN) was slowly added dropwise to reaction system 1). The addition time was controlled within 15-30 minutes. After the addition was complete, heating was started to maintain the reaction system temperature at 60°C-70°C. The reaction time was 2-3 hours. After the reaction was completed, the reaction mixture was allowed to cool naturally to room temperature. The solid product was then separated from the liquid product by centrifugation. The solid product was redispersed in acetone and ultrasonically dispersed for 5 minutes. It was then centrifuged again and repeated 3-4 times until the washing liquid was colorless and transparent to remove unreacted monomers, homopolymers and other impurities physically adsorbed on the surface of the product. The product was then transferred to a vacuum drying oven at 50°C-60°C for drying for about 6-8 hours. The dried block product was then gently crushed with an agate mortar and then sieved through a 100-150 mesh sieve to obtain a loose, free-flowing colored powder product, namely the ionic liquid modified metallic pigment.

[0009] In this process, the anions of the ionic liquid are first adsorbed onto the surface of the metallic pigment, forming a monolayer. Subsequently, under thermal initiation, the vinyl groups on the ionic liquid cations undergo a copolymerization reaction with the simultaneously added methyl methacrylate and coloring monomer mixture, thereby growing colored polymer chains in situ on the surface of the metallic pigment, resulting in an ionic liquid-modified metallic pigment. The reaction equation is shown below: a. Ionic liquid anions [TFSI]⁻ adsorbed onto the surface of metallic pigments: ; b. Chain initiation: Surface ionic liquid cations [VEIM] + The double bond is initiated by the initiator azobisisobutyronitrile: ; c. Chain growth: Addition of chain radicals to methyl methacrylate and coloring monomers containing polymerizable double bonds: ; d. Schematic diagram of the structure of ionic liquid-modified metallic pigments: .

[0010] Preferably, the polymerizable ionic liquid in 1) is 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide ([VEIM)). + [TFSI]⁻).

[0011] Preferably, the low-boiling-point organic solvent in 1) is acetone or ethanol.

[0012] Preferably, the metallic pigment in 1) is non-floating flake aluminum powder with a particle size D50 of 15-30 μm.

[0013] Preferably, the inert gas in 1) is nitrogen, and the flow rate is 50-100 mL / min.

[0014] Preferably, in step 2), the mass ratio of methyl methacrylate to the coloring monomer containing polymerizable double bonds is 17-19:1-3, and the coloring monomer containing polymerizable double bonds is Disperse Red 1 acrylate.

[0015] Preferably, in step 2), the amount of azobisisobutyronitrile used accounts for 0.5%-1.0% of the total mass of the monomer.

[0016] Preferably, the bisphenol A type epoxy resin has an epoxy equivalent of 700-1000 and is purchased from Guodu Chemical Co., Ltd.; the carboxyl polyester resin has an acid value of 28-36 mgKOH / g and a glass transition temperature usually higher than 55°C and is purchased from Anhui Shenjian Technology Co., Ltd.

[0017] Preferably, the curing agent is a phenolic curing agent, such as ALBESTER 5900 from Zhanxin Company.

[0018] Preferably, the leveling agent is an acrylate leveling agent, such as Evonik's RESIFLOW PV88.

[0019] Preferably, the texture agent is an acrylic polymer texture agent, such as Evonik's ADDITIVE P 200. This invention provides a method for preparing a colored metallic textured powder coating, comprising the following steps: S1. Preparation of ionic liquid-modified metallic pigments; S2. Preparation of base powder: Weigh epoxy resin, polyester resin, curing agent, leveling agent, benzoin and precipitated barium sulfate according to the formula weight parts. Put all the above components into a high-speed mixer and mix at 300-500 rpm for 3-5 minutes at room temperature until the material is uniformly mixed. Feed the premixed material into a twin-screw extruder and control the temperature of zone I to 90-100°C and the temperature of zone II to 100-110°C for melt extrusion. The extruded molten material is immediately passed through a sheeting and cooling roller unit to be pressed into thin sheets. The sheets are then rapidly cooled to room temperature through a cooling water circulation system. The cooled sheets are then fed into a high-speed mechanical pulverizer for preliminary crushing. The crushed material is then finely pulverized by the mechanical pulverizer. Finally, the pulverized powder is sieved through a 180-200 mesh vibrating screen to obtain base powder with uniform particle size distribution. S3, Bonding and Composite: The base powder prepared in S2, the ionic liquid modified metallic pigment and the texture agent prepared in S1 are put into the mixing pot of the bonding machine. The bonding machine is started and the materials are initially mixed for 3-5 minutes under stirring at a speed of 20-50 rpm. Then, the material temperature is slowly and evenly raised to the bonding temperature of 40-50°C. During this process, the stirring speed is maintained at 200-400 rpm and the mixing time is about 15-25 minutes. The surface of the base powder particles is slightly softened, thereby producing a strong adhesion with the ionic liquid modified metallic pigment and texture agent particles, achieving uniform physical coating and composite. After the bonding process is completed, heating is stopped, stirring is continued, and the material is allowed to cool naturally to room temperature in the pot. S4. Post-processing of the product: After S3 bonding and lamination, the material is cooled to room temperature and sieved through a 100-150 mesh inspection sieve to disperse any soft agglomerates that may form during the cooling process, ensuring the flowability and dispersibility of the product. After sieving, the colored metallic textured cotton effect powder coating is obtained and then sealed and packaged.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. Through in-situ polymerization technology mediated by ionic liquid, a dense and firm organic polymer coating layer is formed on the surface of metallic pigments. This coating layer can effectively isolate water, oxygen and other corrosive media, significantly improve the oxidation resistance and chemical stability of metallic pigments, enable the coating to maintain a bright metallic texture for a long time, and improve production safety.

[0021] 2. Through copolymerization, the chromophores of the coloring monomers are directly bonded to the polymer layer on the surface of the metallic pigment via covalent bonds. This enables the color to be combined with the underlying metal at the molecular level, with the color surrounding the metallic luster, creating a sense of layering and depth. This solves the problem of separation between color and metallic feel. At the same time, chemical bonding ensures uniform color distribution without defects such as streaks or color differences.

[0022] 3. The polymer layer grafted onto the surface of the metallic pigment has a slight difference in surface tension compared to the matrix resin, and the functional groups on the modified pigment participate in the curing process, introducing controllable non-uniformity during the curing process. This inside-out design can self-induce the formation of uniform and delicate cotton-like patterns, reducing the absolute dependence on traditional cotton-like texture additives, making the effect more natural, more stable, and more repeatable.

[0023] 4. The polymer graft layer has good compatibility with the matrix resin and is anchored by ionic liquid, forming a strong chemical bond or physical entanglement with the matrix. This enables the metallic pigments to achieve ultra-uniform dispersion and strong bonding with the matrix, significantly improving the mechanical strength, adhesion and durability of the coating. Attached Figure Description

[0024] Figure 1 This is a process flow diagram for preparing a colored metallic textured powder coating according to the present invention. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] Example 1: A colored metallic textured powder coating, comprising the following components by weight: 35 parts of bisphenol A type epoxy resin, 35 parts of carboxylated polyester resin, 15 parts of ionic liquid modified metallic pigment, 5 parts of curing agent, 1.0 part of leveling agent, 0.5 parts of benzoin, 20 parts of precipitated barium sulfate, and 0.5 parts of texture agent; Reference Figure 1 The coating is prepared as follows: S1. Ionic liquid-modified metallic pigments are prepared through the following steps: 1) Pretreatment of metallic pigments: Dissolve 3g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt in 200ml of acetone and stir at 250 rpm for 30min at room temperature to form a clear 1.5wt% modified solution; add 100g of non-floating flake aluminum powder (particle size D50=20μm) to the above modified solution and stir continuously at 350 rpm for 45min to form a uniform suspension. Then, introduce high-purity nitrogen gas into the reaction system at a flow rate of 80mL / min for 25min to remove oxygen from the system. 2) Preparation of ionic liquid modified metallic pigment: Under continuous nitrogen purging and stirring, a mixture of 37g methyl methacrylate, 3g Disperse Red 1 methacrylate and 0.4g azobisisobutyronitrile was slowly added dropwise to reaction system 1) over 20 min through a constant pressure dropping funnel. The temperature was then raised to 65°C and reacted for 3 h. After the reaction was completed, the mixture was cooled to room temperature, and the solid product was separated by centrifugation. The product was ultrasonically dispersed with acetone for 5 min and then washed by centrifugation. This process was repeated 3 times until the washing liquid was colorless. The product was vacuum dried at 55°C for 7 h, crushed and passed through a 120-mesh sieve to obtain a red ionic liquid modified metallic pigment.

[0027] S2. Preparation of base powder: Weigh epoxy resin, polyester resin, curing agent, leveling agent, benzoin and precipitated barium sulfate according to the formula weight parts. Put all the above components into a high-speed mixer and mix at 400 rpm for 4 minutes at room temperature until the material is uniformly mixed. Feed the premixed material into a twin-screw extruder and control the temperature of zone I to 95°C and zone II to 105°C for melt extrusion. The extruded molten material is immediately passed through a sheeting and cooling roller unit to be pressed into thin sheets. The sheets are then rapidly cooled to room temperature through a cooling water circulation system. The cooled sheets are then fed into a high-speed mechanical pulverizer for preliminary crushing. The crushed material is then finely pulverized by the mechanical pulverizer. Finally, the pulverized powder is sieved through a 180-mesh vibrating screen to obtain base powder with uniform particle size distribution. S3, Bonding Composite: The base powder prepared in S2, the ionic liquid modified metallic pigment and the texture agent prepared in S1 are put into the mixing pot of the bonding machine. The bonding machine is started and initially mixed at 30 rpm for 4 minutes. Then, the temperature is uniformly raised to 45°C for bonding and bonded at 300 rpm for 20 minutes. After the bonding process is completed, the heating is stopped, stirring is continued and the material is allowed to cool naturally to room temperature in the pot. S4. Post-processing of the product: After bonding and laminating S3, the material is cooled to room temperature and sieved through a 120-mesh inspection sieve. After sieving, the colored metallic textured cotton effect powder coating is obtained and then sealed and packaged.

[0028] Example 2: A colored metallic textured powder coating, comprising the following components by weight: 32 parts of bisphenol A type epoxy resin, 38 parts of carboxylated polyester resin, 12 parts of ionic liquid modified metallic pigment, 4.5 parts of curing agent, 1.2 parts of leveling agent, 0.4 parts of benzoin, 18 parts of precipitated barium sulfate, and 0.8 parts of texture agent; Reference Figure 1 The coating is prepared as follows: S1. Ionic liquid-modified metallic pigments are prepared through the following steps: 1) Pretreatment of metallic pigments: 2.5g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt was dissolved in 150ml of acetone and stirred at 280 rpm for 25min at room temperature to form a clear 1.7wt% modified solution; 80g of non-floating flake aluminum powder (particle size D50=25μm) was added to the above modified solution and stirred continuously at 380rpm for 40min to form a uniform suspension. Then, high-purity nitrogen gas was introduced into the reaction system at a flow rate of 70mL / min for 30min to remove oxygen from the system. 2) Preparation of ionic liquid modified metallic pigment: Under continuous nitrogen purging and stirring, a mixture of 34g methyl methacrylate, 4g Disperse Red 1 methacrylate and 0.38g azobisisobutyronitrile was slowly added dropwise to reaction system 1) over 25 min through a constant pressure dropping funnel. The temperature was then raised to 68°C and reacted for 2.5 h. After the reaction was completed, the mixture was cooled to room temperature, and the solid product was separated by centrifugation. The product was ultrasonically dispersed with acetone for 5 min and then washed by centrifugation. This process was repeated 3 times until the washing liquid was colorless. The product was vacuum dried at 60°C for 6 h, crushed and passed through a 150-mesh sieve to obtain a red ionic liquid modified metallic pigment.

[0029] S2. Preparation of base powder: Weigh epoxy resin, polyester resin, curing agent, leveling agent, benzoin and precipitated barium sulfate according to the formula weight parts. Put all the above components into a high-speed mixer and mix at 400 rpm for 4 minutes at room temperature until the material is uniformly mixed. Feed the premixed material into a twin-screw extruder and control the temperature of zone I to 95°C and zone II to 105°C for melt extrusion. The extruded molten material is immediately passed through a sheeting and cooling roller unit to be pressed into thin sheets. The sheets are then rapidly cooled to room temperature through a cooling water circulation system. The cooled sheets are then fed into a high-speed mechanical pulverizer for preliminary crushing. The crushed material is then finely pulverized by the mechanical pulverizer. Finally, the pulverized powder is sieved through a 180-mesh vibrating screen to obtain base powder with uniform particle size distribution. S3, Bonding Composite: The base powder prepared in S2, the ionic liquid modified metallic pigment and the texture agent prepared in S1 are put into the mixing pot of the bonding machine. The bonding machine is started and initially mixed at 35 rpm for 3 minutes. Then, the temperature is uniformly raised to the bonding temperature of 48°C and bonded at 350 rpm for 18 minutes. After the bonding process is completed, the heating is stopped, stirring is continued and the material is allowed to cool naturally to room temperature in the pot. S4. Post-processing of the product: After bonding and laminating S3, the material is cooled to room temperature and sieved through a 120-mesh inspection sieve. After sieving, the colored metallic textured cotton effect powder coating is obtained and then sealed and packaged.

[0030] Example 3: A colored metallic textured powder coating, comprising the following components by weight: 38 parts of bisphenol A type epoxy resin, 32 parts of carboxylated polyester resin, 18 parts of ionic liquid modified metallic pigment, 6 parts of curing agent, 0.9 parts of leveling agent, 0.55 parts of benzoin, 22 parts of precipitated barium sulfate, and 1.2 parts of texture agent; Reference Figure 1 The coating is prepared as follows: S1. Ionic liquid-modified metallic pigments are prepared through the following steps: 1) Pretreatment of metallic pigments: 4g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt was dissolved in 250ml of acetone and stirred at 220 rpm for 35min at room temperature to form a clear 1.6wt% modified solution; 120g of non-floating flake aluminum powder (particle size D50=18μm) was added to the above modified solution and stirred continuously at 320rpm for 50min to form a uniform suspension. After that, high-purity nitrogen gas was introduced into the reaction system at a flow rate of 90mL / min for 20min to remove oxygen from the system. 2) Preparation of ionic liquid modified metallic pigment: Under continuous nitrogen purging and stirring, a mixture of 39g methyl methacrylate, 2g Disperse Red 1 methacrylate and 0.41g azobisisobutyronitrile was slowly added dropwise to reaction system 1) over 18min through a constant pressure dropping funnel. The temperature was then raised to 62°C and reacted for 3.5h. After the reaction was completed, the mixture was cooled to room temperature, and the solid product was separated by centrifugation. The product was ultrasonically dispersed with acetone for 5min and then washed by centrifugation. This process was repeated 3 times until the washing liquid was colorless. The product was vacuum dried at 50°C for 8h, crushed and passed through a 100-mesh sieve to obtain a red ionic liquid modified metallic pigment.

[0031] S2. Preparation of base powder: Weigh epoxy resin, polyester resin, curing agent, leveling agent, benzoin and precipitated barium sulfate according to the formula weight parts. Put all the above components into a high-speed mixer and mix at 400 rpm for 4 minutes at room temperature until the material is uniformly mixed. Feed the premixed material into a twin-screw extruder and control the temperature of zone I to 95°C and zone II to 105°C for melt extrusion. The extruded molten material is immediately passed through a sheeting and cooling roller unit to be pressed into thin sheets. The sheets are then rapidly cooled to room temperature through a cooling water circulation system. The cooled sheets are then fed into a high-speed mechanical pulverizer for preliminary crushing. The crushed material is then finely pulverized by the mechanical pulverizer. Finally, the pulverized powder is sieved through a 180-mesh vibrating screen to obtain base powder with uniform particle size distribution. S3, Bonding Composite: The base powder prepared in S2, the ionic liquid modified metallic pigment and the texture agent prepared in S1 are put into the mixing pot of the bonding machine. The bonding machine is started and initially mixed at 25 rpm for 5 minutes. Then, the temperature is uniformly raised to 42°C and bonded at 250 rpm for 25 minutes. After the bonding process is completed, the heating is stopped, stirring is continued and the material is allowed to cool naturally to room temperature in the pot. S4. Post-processing of the product: After bonding and laminating S3, the material is cooled to room temperature and sieved through a 120-mesh inspection sieve. After sieving, the colored metallic textured cotton effect powder coating is obtained and then sealed and packaged.

[0032] Comparative Example 1: Based on Example 1, the difference is that the metallic pigment is the same unmodified non-floating flake aluminum powder (particle size D50=20μm), and the rest is the same as in Example 1.

[0033] Comparative Example 2: Based on Example 1, the difference is that the preparation process of the ionic liquid modified metallic pigment does not contain the coloring monomer (Dispersion Red 1 acrylate), but only uses 40g of methyl methacrylate for polymerization reaction to obtain colorless and transparent polymer-coated aluminum powder, and the rest is the same as in Example 1.

[0034] Comparative Example 3: Based on Example 1, the difference is that the bonding and compounding step S3 is omitted. Instead, the ionic liquid modified metallic pigment and texture agent prepared in S1 are added to a high-speed mixer along with other components during the preparation of the base powder in S2 for premixing. Then, subsequent steps such as melt extrusion and pulverization are performed. The rest is the same as in Example 1.

[0035] Comparative Example 4: Based on Example 1, the difference is that in the preparation of the ionic liquid modified metallic pigment, instead of using a polymerizable ionic liquid (1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt), an equal amount of a common surfactant (such as sodium dodecylbenzenesulfonate) is used as a dispersant. The polymerization reaction of methyl methacrylate and coloring monomer still takes place on the surface of aluminum powder in an attempt to form a coating layer. The rest is the same as in Example 1.

[0036] Comparative Example 5: Based on Example 1, the difference is that the addition of the cotton-texturing agent (ADDITIVE P 200) was omitted, and the rest is the same as Example 1.

[0037] Performance testing: 1. Color effect test (QUV aging): The samples prepared in Examples 1-3 and Comparative Examples 1-5 were placed in a QUV accelerated aging test chamber and tested for 500 hours under the conditions of UVA-340 lamp, 60℃ light irradiation, and 50℃ condensation cycle. After the test, the color difference (ΔE) of the samples before and after aging was measured using a colorimeter. The experimental results are shown in Table 1.

[0038] 2. Metallic gloss test: The samples prepared in Examples 1-3 and Comparative Examples 1-5 were tested for surface gloss using a 60° gloss meter according to GB / T 9754 standard. The experimental results are shown in Table 1.

[0039] 3. Salt spray resistance test: The samples prepared in Examples 1-3 and Comparative Examples 1-5 were scratched through the coating to the intersection line of the substrate and placed in a neutral salt spray test chamber. The test was carried out according to GB / T 1771 standard. After 500 hours, the samples were taken out, rinsed with pure water and dried. The erosion width on both sides of the scratch and the blistering and peeling of the coating were observed. The experimental results are shown in Table 1.

[0040] 4. Texture effect: The samples prepared in Examples 1-3 and Comparative Examples 1-5 were visually evaluated under a standard light source box, focusing on the uniformity, clarity and fineness of the texture. The experimental results are shown in Table 1.

[0041] 5. Abrasion resistance test: The samples prepared in Examples 1-3 and Comparative Examples 1-5 were tested using a Taber abrasion tester with a CS-10 grinding wheel according to GB / T 1768 standard. A load of 750g was applied and the samples were rotated 500 times. The mass loss of the coating was then measured. The experimental results are shown in Table 1.

[0042] 6. Adhesion test: The samples prepared in Examples 1-3 and Comparative Examples 1-5 were tested according to GB / T 9286 standard using the cross-cut test method with a cut spacing of 1 mm. After being adhered with adhesive tape, the samples were quickly peeled off, and the coating peeling level was observed. The experimental results are shown in Table 1.

[0043] 7. Impact resistance test: The samples prepared in Examples 1-3 and Comparative Examples 1-5 were tested using an impact tester according to GB / T 1732 standard. The weight of the hammer was 1 kg and the impact height was 50 cm. The coating was observed to see if cracks or peeling occurred. The test results are shown in Table 1.

[0044] Table: Performance tests were conducted on a colored metallic textured powder coating of Examples 1-3 and Comparative Examples 1-5.

[0045] Table 1. Effects of different formulations and process parameters on the performance of powder coatings

[0046] Data Analysis: 1. Durability Analysis: Examples 1-3 exhibited excellent and consistent durability, with minimal scratch propagation (<1mm) in salt spray tests, low abrasion resistance mass loss (16-20mg), and small color difference ΔE value after QUV aging (1.8-2.4). This fully demonstrates the effectiveness of the polymer coating layer formed by ionic liquid-mediated in-situ polymerization. This coating layer is like a protective suit for aluminum powder, effectively isolating it from the erosion of water, oxygen, and corrosive ions, thereby preventing the aluminum powder from oxidizing and losing its gloss (reflected in the low ΔE value), and enhancing the overall density and abrasion resistance of the coating. Comparative Example 1 (unmodified aluminum powder) showed very poor data, with extremely poor salt spray resistance, severe wear, and huge color difference (ΔE=12.5), which directly exposed the inherent defects of traditional physically mixed aluminum powder. The aluminum powder oxidized rapidly during processing and testing, becoming a weak point in the coating and causing a complete loss of protective function. The durability of Comparative Example 3 (fully melt extrusion) and Comparative Example 4 (ordinary surfactant) was also significantly worse than that of the Example. Comparative Example 3 shows that subjecting the effect pigment to a high-temperature, high-shear melt extrusion process is destructive, damaging not only the pigment itself but also potentially the resin system. Comparative Example 4 shows that the physically adsorbed ordinary surfactant coating layer is not strong enough and is prone to failure under harsh testing, failing to provide lasting protection. The durability of Comparative Examples 2 and 5 was close to that of the Example, indicating that their coating matrix structure was intact. This highlights that the excellent durability of the Example mainly stems from the chemical stability of the pigment coating layer, rather than the difference in the matrix resin.

[0047] 2. Decorative Effect and Optical Performance Analysis: Examples 1-3 successfully achieved the integration of color, metal, and texture, exhibiting a moderate gloss (42-57 GU), an elegant, soft metallic feel rather than a cheap, mirror-like shine. The most significant breakthrough is the minimal color difference maintained even after QUV aging, indicating a very stable bond between the color and the metallic substrate. Simultaneously, the textured effect was rated as delicate, uniform, and clear, demonstrating the synergistic effect of the modified pigment and texture agent during curing, forming a natural and controllable texture from the inside out. Comparative Example 2 (without coloring monomers) exhibited an excessively high gloss (85-90 GU), displaying a mirror-like effect, and... The complete absence of color directly proves that the participation of coloring monomers in in-situ polymerization is a necessary condition for achieving a colored metallic effect. Without it, only a traditional silver metallic coating can be obtained. The texture of Comparative Example 5 (without texture agent) is shallow and lacks integrity. This is key evidence that although the modified pigment itself can induce a certain texture, it must work in conjunction with an added texture agent to obtain the full and clear decorative texture sought by this invention. Comparative Examples 1, 3, and 4 failed in terms of decoration, either turning black due to oxidation (Comparative Example 1), or having messy textures and pinholes due to uneven dispersion (Comparative Examples 1 and 4), or having the texture disappear due to process damage (Comparative Example 3). This highlights the great advantage of this invention in solving the problems of pigment dispersibility and process compatibility.

[0048] 3. Mechanical Performance Analysis: Examples 1-3 all exhibited the best adhesion (Grade 0) and impact resistance, mainly due to the bonding composite process. This process is carried out at low temperature (40-50℃), avoiding thermal damage to the base resin, curing agent, and effect pigments, thus perfectly preserving the inherent excellent mechanical properties of the base material. At the same time, the physical coating of the modified pigments and base material particles is strong, without introducing obvious weak interfaces. The adhesion and impact resistance of Comparative Example 3 (full melt extrusion) are both unqualified, which strongly proves the potential harm of the traditional full melt extrusion process to the mechanical properties of the coating. High temperature and shear force may cause partial pre-curing or degradation of the resin, thereby weakening the toughness and adhesion of the coating. The mechanical properties of Comparative Examples 1 and 4 decreased because the unmodified or poorly coated pigments have weak bonding with the base resin. When subjected to external force, these interface points fail first, resulting in a decrease in adhesion grade and weakened impact resistance.

[0049] 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 colored metallic textured powder coating, characterized in that, Includes the following components by weight: 30-40 parts of bisphenol A type epoxy resin; 30-40 parts of carboxylated polyester resin; 10-20 parts of ionic liquid-modified metallic pigment; 4-7 parts of curing agent; Leveling agent 0.8-1.5 parts; Benzoin 0.3-0.6 parts; Precipitate 15-25 parts of barium sulfate; Cotton-texturing agent: 0.5-1.5 parts; The ionic liquid-modified metallic pigment is prepared by in-situ polymerization of methyl methacrylate and a coloring monomer containing polymerizable double bonds mediated by a polymerizable ionic liquid on the surface of the metallic pigment, as follows: 1) Dissolve the polymerizable ionic liquid in a low-boiling-point organic solvent to prepare a 1-5 wt% modified solution, then add flake metal pigments to disperse and form a suspension, and pass inert gas to remove oxygen. 2) Under an inert atmosphere, a mixture of methyl methacrylate, a coloring monomer containing polymerizable double bonds, and the initiator azobisisobutyronitrile is added dropwise to the system in 1). The mixture is reacted at 60-70°C for 2-3 hours. After the reaction is completed, the ionic liquid modified metallic pigment is obtained by centrifugation, washing, drying, and sieving.

2. The colored metallic textured powder coating according to claim 1, characterized in that, The polymerizable ionic liquid in 1) is 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt; the flake-shaped metallic pigment is non-floating flake aluminum powder with a particle size D50 of 15-30 μm; the low-boiling-point organic solvent is acetone or ethanol; the inert gas is nitrogen with a flow rate of 50-100 mL / min.

3. The colored metallic textured powder coating according to claim 1, characterized in that, In step 2), the mass ratio of methyl methacrylate to the coloring monomer containing polymerizable double bonds is 17-19:1-3, and the coloring monomer with polymerizable double bonds is Disperse Red 1 acrylate; azobisisobutyronitrile accounts for 0.5%-1.0% of the total mass of the monomers.

4. The colored metallic textured powder coating according to claim 1, characterized in that, The bisphenol A type epoxy resin has an epoxy equivalent of 700-1000; the carboxyl polyester resin has an acid value of 28-36 mgKOH / g.

5. The colored metallic textured powder coating according to claim 1, characterized in that, The curing agent is a phenolic curing agent, ALBESTER 5900.

6. The colored metallic textured powder coating according to claim 1, characterized in that, The leveling agent is RESIFLOW PV88, an acrylate leveling agent.

7. The colored metallic textured powder coating according to claim 1, characterized in that, The texture agent is an acrylic polymer texture agent, ADDITIVE P 200.

8. The preparation of a colored metallic textured powder coating as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Preparation of ionic liquid-modified metallic pigments; S2. Preparation of base powder: Bisphenol A type epoxy resin, carboxylated polyester resin, curing agent, leveling agent, benzoin, and precipitated barium sulfate are mixed and fed into a twin-screw extruder. The temperature of zone I is controlled at 90-100°C and the temperature of zone II is controlled at 100-110°C. After melt extrusion, tableting and cooling, crushing and sieving, the base powder is obtained. S3, Bonding Composite: The base powder obtained in S2 is mixed and stirred in a bonding machine at 40-50°C and 200-400 rpm for 15-25 minutes with the ionic liquid modified metallic pigment and the texture agent obtained in S1 to achieve physical coating and composite. S4. Post-processing of the product: Cool and sieve the bonded composite material to obtain the final product.

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