Multifunctional composite powder coating composition and plate coated with multifunctional composite powder coating

Abstract

The invention discloses a multifunctional composite powder coating composition and a plate coated with a multifunctional composite powder coating. The multifunctional composite powder coating composition comprises the following components in parts by weight: 55-70 parts of a matrix resin system; 8-13 parts of a dual-curing crosslinking system; 20.05 to 33.2 parts of a composite reinforcing system; 8-15 parts of a multifunctional modification system; the composite reinforcing system comprises nano-porous copper-titanium alloy powder. Through substrate plating layer optimization, coating component collaborative design and process innovation, the comprehensive performance breakthrough of the coated steel plate in the aspects of corrosion resistance, scratch resistance, function integration and the like is achieved, and the long-acting protection and intelligent requirements of high-end industrial scenes for materials are met.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, in particular to a multifunctional composite powder coating composition and a plate coated with the multifunctional composite powder coating. Background Art

[0002] As a composite material with both protective and decorative properties, the technological development of color-coated steel sheets has always revolved around the coordinated optimization of the substrate's anti-corrosion properties and the coating's functionality. Traditional processes generally use hot-dip galvanizing (GI), electrogalvanizing (EG), or hot-dip galvanizing (GL) as the substrate, and apply organic coatings such as polyester (PE), fluorocarbon (PVDF), and silicon-modified polyester (SMP) through a roller coating process. However, with the increasing demand for material weather resistance, mechanical strength, and functional integration in modern industry, the existing technology system has gradually exposed the following structural defects:

[0003] 1. Boundary effect of substrate corrosion protection

[0004] Traditional galvanized substrates rely on the sacrificial anode protection mechanism of the zinc layer, but during processing such as shearing and punching, the continuity of the coating is destroyed, resulting in direct exposure of the substrate at the cut. For example, the cut of hot-dip galvanized steel sheet will show red rust within 48 hours in an environment with humidity greater than 60%, and its salt spray resistance time is only 300-500 hours (GB / T 10125 standard), which is difficult to meet the long-term protection requirements of harsh environments such as marine climates or industrial pollution areas. This defect not only forces downstream users to increase the cost of secondary protection such as passivation treatment and sealant filling, but also restricts the application boundaries of color-coated sheets in high-end scenarios such as chemical facilities and coastal buildings.

[0005] 2. Process ceiling of coating mechanical strength

[0006] Limited by the low-temperature (120-160°C) and short-time (20-40 seconds) curing characteristics of the roller coating process, traditional organic coatings are difficult to achieve sufficient cross-linking reaction. Taking mainstream polyester coatings as an example, their pencil hardness is only HB grade (GB / T 6739-2006), and the Taber abrasion test weight loss is >100mg / 1000 times (ISO 7784-2). In high-frequency contact scenarios such as building curtain wall installation and home appliance housing assembly, the coating is easily damaged locally due to mechanical scratches, forming weak points for corrosion diffusion. Existing technologies compensate for strength defects by increasing the coating thickness (>25μm), but this sacrifices the flexibility of the material and increases the risk of stress cracking in the coating.

[0007] 3. The Dilemma of Discrete Functional Modules

[0008] Currently, the functional design of color-coated steel sheets is largely limited to basic corrosion protection and color decoration. To meet the antimicrobial and antistatic requirements of scenarios like medical cleanrooms and electronics workshops, traditional technologies often rely on "patching" solutions such as post-application film or surface modifier coating. For example, while GB / T 12754-2019 specifies functional indicators such as antifouling and self-cleaning, the poor compatibility of conventional organic resins with nano-additives results in coating antimicrobial rates of less than 90% (ISO 22196) and surface resistivities greater than 10^12Ω (IEC61340-2-1), making it impossible to achieve long-term, stable performance of these functional properties. Summary of the Invention

[0009] To address technical bottlenecks associated with traditional color-coated steel sheets, such as susceptible corrosion at the substrate cutouts, insufficient coating hardness, and limited functionality, the present invention provides a multifunctional composite powder coating composition and sheet material coated with the multifunctional composite powder coating. Through substrate coating optimization, collaborative design of coating components, and process innovation, the coated steel sheet achieves breakthroughs in comprehensive performance, including corrosion resistance, scratch resistance, and functional integration, meeting the demand for long-term material protection and intelligent functionality in high-end industrial applications.

[0010] The object of the present invention is achieved through the following technical solutions:

[0011] <First Aspect>

[0012] A multifunctional composite powder coating composition comprises the following components in parts by weight:

[0013] 55-70 parts of matrix resin system;

[0014] 8-13 parts of dual-cure cross-linking system;

[0015] Composite reinforcement system 20.05-33.2 parts;

[0016] 8-15 parts of multifunctional modification system;

[0017] The composite reinforcement system includes nanoporous copper-titanium alloy powder.

[0018] The matrix resin system comprises, by weight:

[0019] 35-45 parts epoxy resin

[0020] 20-25 parts of polyacid resin.

[0021] By weight, the dual-cure cross-linking system comprises:

[0022] 5-8 parts of amine curing agent;

[0023] 3-5 parts of isocyanate curing agent.

[0024] By weight, the composite reinforcement system includes:

[0025] 3-5 parts of nano silicon dioxide;

[0026] 2-3 parts of nano-alumina;

[0027] 0.05-0.2 parts of nanoporous copper-titanium alloy powder;

[0028] 10-15 parts of titanium dioxide;

[0029] 5-10 parts of talcum powder.

[0030] Nano-silicon dioxide has a particle size of 10-100nm; nano-alumina has a particle size of 20-150nm; titanium dioxide has a median particle size D50 of 0.2-0.8μm; and talc has a median particle size of 10μm-100μm.

[0031] The nanoporous copper-titanium alloy powder is prepared by a dealloying method, which comprises the following steps:

[0032] 1) Preparation of Cu-Ti alloy thin films by magnetron sputtering;

[0033] 2) placing the alloy film in a 0.13-0.2M HF solution and subjecting it to corrosion treatment at 10-30°C for 10-14 hours;

[0034] 3) The material treated in step 2) is washed and dried to obtain nanoporous copper-titanium alloy powder.

[0035] The pore size of the nanoporous copper-titanium alloy powder is 50-200 nm.

[0036] In parts by weight, the multifunctional modification system comprises:

[0037] 1-2 parts of leveling agent;

[0038] 2-3 parts of toughening agent;

[0039] 0.5-1 part of ultraviolet absorber;

[0040] 0.5-1 part of antistatic agent;

[0041] 2-4 portions of self-repairing microcapsules;

[0042] 1-2 parts of thermochromic material;

[0043] 0.5-1 part of antibacterial nanosilver particles;

[0044] High-efficiency curing accelerator 0.5-1 part.

[0045] The epoxy resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin.

[0046] The bisphenol A type includes E-12 type.

[0047] The polyacid resin includes one or more of acrylic acid (PAA), polymethacrylic acid (PMAA), and maleic anhydride copolymer.

[0048] Preferably, the polyacid resin includes PA-20 type polyacid resin.

[0049] The amine curing agent includes one or more of aliphatic amine curing agents, aromatic amine curing agents, alicyclic amine curing agents, polyamide curing agents, and tertiary amine curing agents.

[0050] Fatty amine curing agents include primary amines or modified fatty amines.

[0051] The aromatic amine curing agent includes one or more of metaphenylenediamine (MPDA), diaminodiphenylmethane (DDM), diaminodiphenyl sulfone (DDS), and modified aromatic amine.

[0052] The alicyclic amine curing agent includes one or more of isophorone diamine (IPDA), 1,3-cyclohexane diamine (1,3-BAC), and menthane diamine (MDA).

[0053] The polyamide curing agent includes one or more of polyamide 650, 651 (low molecular weight) and polyamide 1250 (high molecular weight).

[0054] The tertiary amine curing agent includes one or more of triethylamine (TEA), benzyldimethylamine (BDMA), and 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30).

[0055] The isocyanate curing agent is selected from one or more of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), IPDI trimer (such as Vestanat T1890), dicyclohexylmethane diisocyanate (H12MDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), prepolymer isocyanate, blocked isocyanate, tetramethylxylylene diisocyanate (TMXDI), and xylylene diisocyanate (XDI).

[0056] The leveling agent is selected from at least one of polysiloxane, polyether-modified polysiloxane, polyester-modified polysiloxane, pure acrylate copolymer, modified acrylate, and fluorine-modified polymer.

[0057] The toughening agent is selected from liquid polysulfide rubber, carboxyl-terminated nitrile rubber (CTBN), acrylic rubber (ACM), polyethersulfone (PES), polyetherketone (PEK), polyurethane elastomer, MBS (methyl methacrylate-butadiene-styrene copolymer), ACR (acrylate core-shell particles), nanoparticle toughening agent; at least one of epoxy toughening agent, polyurethane prepolymer, long-chain aliphatic compound, and hyperbranched polymer

[0058] The ultraviolet absorber is selected from at least one of the following: benzotriazoles, benzophenones, triazines, hindered amines (HALS), oxalic acid anilides, and cyanoacrylates.

[0059] The antibacterial nanosilver particles are nanosilver particles with a loading of 5-8 wt% and a particle size distribution of 10-50 nm;

[0060] The curing accelerator is selected from one or more of epoxy resin accelerators (tertiary amines, imidazoles, acetylacetonate metal salts), polyurethane accelerators (organic tin, amines, bismuth), free radical accelerators (photoinitiator synergists, peroxide activators), ionic catalyst accelerators (acid / base catalysis type), and click chemistry reaction accelerators (thiol-ene system).

[0061] The antistatic agent is a carbon black composite, which is composed of conductive carbon black (particle size of 10-50 nm), epoxy resin (E-12 type) and solvent (xylene) in a mass ratio of (5-7): (2-4): (0.8-1.2). The preparation method is as follows:

[0062] Conductive carbon black and epoxy resin are premixed in proportion, and xylene solvent is added; the mixture is dispersed in a high-speed disperser at 1800-2200 rpm for 25-35 minutes to form a uniform slurry; and vacuum degassing is performed to obtain a carbon black composite antistatic agent having a surface resistivity of ≤10^6Ω·m (ASTM D257).

[0063] Thermochromic materials have a color change range of 50-80°C and include the following components in parts by weight:

[0064] 1.0-1.5 parts of crystal violet lactone (coloring agent)

[0065] Bisphenol A (developer) 0.8-1.2 parts

[0066] Tetradecanol (solvent) 4.0-5.0 parts

[0067] 6.0-8.0 parts of epoxy / polyester resin mixture (mass ratio of epoxy resin E-12 type: polyester resin PA-20 type 3:2-1:1)

[0068] Preparation method of thermochromic material: heat tetradecanol to a molten state, add crystal violet lactone and bisphenol A in sequence, and stir until completely dissolved; then add epoxy / polyester resin base material, mix evenly, cool and solidify, and crush to a particle size of ≤10μm.

[0069] <Second Aspect>

[0070] 9. A method for preparing the multifunctional composite powder coating composition according to any one of claims 1 to 8, characterized in that it comprises the following steps:

[0071] (1) Premixing: Add the components of the matrix resin system, dual-cure crosslinking system, composite reinforcement system and multifunctional modification system into a high-speed mixer in proportion, mix at a speed of 1200-1500 rpm for 15-20 minutes under nitrogen protection, and control the material temperature at 10-40°C;

[0072] (2) Melt extrusion: The premixed material is conveyed to a twin-screw extruder, and the temperature of zone I is set to 80-100°C, the temperature of zone II is set to 110-120°C, and the temperature of zone III is set to 115-125°C. The screw speed is set to 200-400 rpm for melt blending and extrusion;

[0073] (3) Cooling and tableting: The extrudate is cooled to 25-35°C and pressed into a sheet material with a thickness of 1.5-2.5 mm;

[0074] (4) Crushing: crushing the flake material into powder particles with a particle size D50 of 30-40 μm and D90 ≤ 60 μm at an environment of -50°C to -30°C;

[0075] (5) Grading and screening: The powder is graded by a turbine airflow classifier to remove agglomerated particles with a particle size greater than 80 μm, and finally the finished powder of 45-75 μm is collected.

[0076] The present invention also provides a hot-dip galvanized aluminum-magnesium color coated steel plate, comprising the following sequentially stacked structures:

[0077] a), substrate;

[0078] b) a primer layer covering the front surface of the substrate, wherein the primer layer is obtained by coating the multifunctional composite powder coating composition according to any one of claims 1 to 8 and has a thickness of 20 to 50 μm;

[0079] c) a topcoat covering the basecoat, the topcoat being obtained by coating the multifunctional composite powder coating composition according to any one of claims 1 to 8, and having a thickness of 30 to 80 μm;

[0080] d) a back coating layer covering the base back side, wherein the back coating layer is obtained by coating the multifunctional composite powder coating composition according to any one of claims 1 to 8 and has a thickness of 15 to 40 μm.

[0081] The substrate can be a hot-dip galvanized aluminum-magnesium substrate including one or more of TDC51D, TDC52D, TDC53D, TDC54D, TDC56D, TS250GD, TS300GD, TS350GD, TS400GD, TS450GD, TS500GD, TS550GD, and TS600GD.

[0082] Coating appearance effects: leveling, wrinkles, orange grain, sand grain, mesh grain, snowflake grain, metal, mirror highlight, etc.

[0083] Compared with the prior art, the present invention has the following beneficial effects:

[0084] 1. The nanoporous structure of the present invention (pore size 10-200nm, specific surface area>50m 2 / g) is prepared through a dealloying method, forming physical anchoring and chemical bonding (Cu-OC bonds) with the polymer matrix, significantly improving interfacial bonding strength. The dual-cure system (amine + isocyanate) creates a rigid-flexible gradient network, achieving stress buffering (T-bend 0T) within the 80-180°C temperature window, resolving the conflict between hardness and toughness in traditional coatings.

[0085] 2. The material achieves multi-dimensional performance breakthroughs: 1) Long-lasting antibacterial (Cu + 1) Slow-release, antibacterial rate ≥99.9%); 2) Self-cleaning (porous adsorption + photocatalytic degradation); 3) Intelligent self-repair (thermochromic material and microcapsules work together to trigger repair at 30-60°C); and Superior corrosion resistance (incision salt spray resistance ≥1500 hours, three times the national standard). For example, the antibacterial and self-cleaning functions work together to inhibit biofilm, while the self-repair and corrosion resistance extend service life.

[0086] 3. Has broad application prospects

[0087] A. Construction field: The salt spray resistance is suitable for the high humidity environment in coastal areas and solves the problem of rust on the cut edges of color-coated plates;

[0088] B. Electronic equipment: to achieve anti-static and meet the dust-proof requirements of precision instruments;

[0089] C. Medical scenarios: Suitable for high-frequency contact surfaces such as sterile operating tables.

[0090] Compared to conventional technologies (GB / T 12754 standard), this invention achieves a generational improvement in core performance: pencil hardness is increased from HB to 3H, impact resistance reaches 60kg·cm; new intelligent features such as self-healing and temperature-sensitive color change are added; and antibacterial and self-cleaning properties fill an industry gap. Through three-dimensional innovation in "material-structure-function," this invention achieves comprehensive advantages across mechanical performance, environmental responsiveness, and maintenance cost-effectiveness, providing a next-generation, high-performance coating solution for the construction, electronics, and medical industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0092] Figure 1 This is a microstructure morphology of porous copper-titanium powder; the magnification is 100,000 times;

[0093] Figure 2 This is a schematic diagram of the structure of the hot-dip galvanized aluminum-magnesium color coated steel plate in Example 3. DETAILED DESCRIPTION

[0094] The present invention will be described in detail below with reference to the examples. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make several adjustments and improvements without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0095] Preparation Example 1 Preparation of Nanoporous Copper-Titanium Alloy Powder

[0096] Step a: magnetron sputtering deposition of Cu-Ti alloy film

[0097] Magnetron sputtering equipment (argon atmosphere, background vacuum ≤ 5×10 -4 Pa), and deposited a Cu-Ti alloy film on a silicon substrate. The sputtering parameters are as follows:

[0098] Target material: pure Cu target (99.99%) and pure Ti target (99.99%), area ratio 3:1;

[0099] Sputtering power: Cu target 150W, Ti target 80W;

[0100] Base temperature: 200±10℃;

[0101] Deposition time: 2 hours, a Cu-Ti alloy film with a thickness of 200±10 nm (Cu:Ti atomic ratio 3:1) was obtained.

[0102] Step b: dealloying corrosion treatment

[0103] The film obtained in step a was immersed in a 0.15M hydrofluoric acid (HF) solution, placed in a constant temperature water bath (25±1°C), and subjected to an assisted corrosion treatment with magnetic stirring (200 rpm) for 12 hours to selectively dissolve the Ti component and form a nanoporous structure.

[0104] Step c: Post-processing and characterization

[0105] Cleaning: After removing the film, ultrasonic cleaning was performed with deionized water (frequency 40 kHz, power 100 W) for 3 times, 10 minutes each time, to remove residual HF and corrosion products;

[0106] Drying: The sample was placed in a vacuum drying oven (50°C, vacuum degree -0.1MPa) and dried for 4 hours to obtain nanoporous copper-titanium alloy powder with a pore size distribution of 100-150nm (the microstructure morphology of the porous copper-titanium powder is as follows Figure 1 ).

[0107] Example 1-2 Preparation of multifunctional composite powder coating composition

[0108] The raw material ratio is shown in Table 1 (parts by weight)

[0109]

[0110]

[0111] in:

[0112] 1. The antistatic agent is a carbon black compound, which is composed of conductive carbon black, epoxy resin (E-12 type) and solvent (xylene) in a mass ratio of 6:3:1. The preparation method is as follows:

[0113] Conductive carbon black (particle size ≤ 50 nm) and epoxy resin were premixed in a certain proportion, and xylene solvent was added. The mixture was dispersed in a high-speed disperser at 2000 rpm for 30 minutes to form a uniform slurry. After vacuum degassing, a carbon black composite antistatic agent was obtained, having a surface resistivity of ≤ 10^6 Ω·m (ASTM D257).

[0114] 2. Thermochromic material (color change range 50-80°C), composed of the following components in parts by weight:

[0115] 1.5 parts of crystal violet lactone (coloring agent)

[0116] 0.8 parts of bisphenol A (developer)

[0117] 4.0 parts of tetradecanol (solvent)

[0118] 6.0 parts of epoxy / polyester resin mixture (Epoxy resin E-12 type: Polyester resin PA-20 type mass ratio 3:2)

[0119] Preparation method: Heat tetradecanol to a molten state, add crystal violet lactone and bisphenol A in sequence, and stir until completely dissolved; then add epoxy / polyester resin base material, mix evenly, cool and solidify, and crush to a particle size of ≤10μm.

[0120] 3. Self-repairing microcapsules (PU shell / epoxy core): refer to the following literature.

[0121] Parsaee, S., Mirabedini, SM, Farnood, R., & Alizadegan, F. (2020). Development of self-healing coatings based on urea-formaldehyde / polyurethanemicrocapsules containing epoxy resin. Journal of Applied Polymer Science, 137(23), 49663.

[0122] 4. The preparation steps of the multifunctional composite powder coating composition are as follows:

[0123] (1) Premixing: Add the components in proportion according to Table 1 into a high-speed mixer and mix at a speed of 1500 rpm for 20 minutes under nitrogen protection, and control the material temperature to ≤40°C;

[0124] (2) Melt extrusion: The premixed materials were conveyed to a twin-screw extruder, and the temperature of zone I was set at 80°C, the temperature of zone II was 110°C, and the temperature of zone III was 125°C. The screw speed was 400 rpm for melt blending and extrusion.

[0125] (3) Cooling and tableting: The extrudate is cooled to 25°C and pressed into a sheet material with a thickness of 2 mm;

[0126] (4) Crushing: crush the flake material into powder particles with a particle size D50 of 30-40 μm and D90 ≤ 60 μm.

[0127] Comparative Example 1

[0128] The difference between Comparative Example 1 and Example 1 is that no nanoporous copper-titanium alloy is added.

[0129] Comparative Example 2

[0130] The difference between Comparative Example 2 and Example 1 is that the polyacid resin (PA-20 type) is replaced by an equal amount of epoxy resin (E-12 type).

[0131] Comparative Example 3

[0132] The difference between Comparative Example 3 and Example 1 is that the epoxy resin (E-12 type) is replaced by an equal amount of polyacid resin (PA-20 type).

[0133] Comparative Example 4

[0134] The difference between Comparative Example 3 and Example 1 is that the amine curing agent (DDS type) is replaced by an equal amount of phenolic curing agent (PN-50 type).

[0135] Comparative Example 5

[0136] The difference between Comparative Example 3 and Example 1 is that the isocyanate curing agent (HDI type) is replaced by an acid anhydride curing agent (MTHPA type) in the same amount.

[0137] Performance Testing

[0138] Hot-dip galvanized aluminum-magnesium color coated steel sheets were prepared using the coatings prepared in Examples 1 and 2 and Comparative Examples 1-5.

[0139] The structure of hot-dip galvanized aluminum-magnesium color coated steel plate ( Figure 2 ) includes: a substrate, a zinc-aluminum-magnesium coating A coated on the upper surface of the substrate, a zinc-aluminum-magnesium coating B coated on the lower surface of the substrate, a primer coated on the zinc-aluminum-magnesium coating A, a top coating covering the primer, and a back coating coated on the zinc-aluminum-magnesium coating B.

[0140] The specific preparation method comprises the following steps:

[0141] a) A hot-dip galvanized aluminum-magnesium substrate, both the upper and lower surfaces of which have a zinc-aluminum-magnesium coating (TS350GD, coating thickness 20 μm) and are degreased and phosphated; the upper surface zinc-aluminum-magnesium coating is denoted as zinc-aluminum-magnesium coating A, and the lower surface zinc-aluminum-magnesium coating is denoted as zinc-aluminum-magnesium coating B;

[0142] b) On the surface of the zinc-aluminum-magnesium coating A, the coatings of Example 1, Example 2, and Comparative Examples 1-5 were respectively applied on one side by a roller coater (roller coating gap 0.4 mm, roller speed 30 m / min) to form a primer layer with a thickness of 30 μm.

[0143] c) On the surface of the primer layer, the coatings of Example 1, Example 2, and Comparative Examples 1-5 were respectively applied on one side by a roller coater (roller gap 0.4 mm, roller speed 30 m / min) to form a topcoat layer with a thickness of 60 μm.

[0144] d) On the surface of the zinc-aluminum-magnesium coating B, the coatings of Example 1, Example 2, and Comparative Examples 1-5 were respectively used and single-sided coated by a roller coater (roller coating gap 0.4 mm, roller speed 30 m / min) to form a primer layer with a thickness of 25 μm.

[0145] e) Curing at 170°C for 7 minutes to form a dense coating.

[0146] The test results are as follows:

[0147]

[0148] The multifunctional composite powder coating composition prepared in Example 1 achieves a balance between hardness (4H) and flexibility (0T bend) through the synergistic effect of a dual-cure system (amine + isocyanate) and a nanoporous copper-titanium alloy. The coating also exhibits excellent salt spray resistance (≥1500 hours), self-healing efficiency (85%), and antibacterial properties (99.98%), meeting the comprehensive performance requirements of color-coated steel sheets in high-end industrial scenarios.

[0149] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A multifunctional composite powder coating composition, characterized in that: Contains the following components in parts by weight: 55-70 parts of matrix resin system; 8-13 parts of dual-cure cross-linking system; Composite reinforcement system 20.05-33.2 parts; 8-15 parts of multifunctional modification system; The composite reinforcement system includes nanoporous copper-titanium alloy powder.

2. The multifunctional composite powder coating composition according to claim 1, characterized in that: By weight, the matrix resin system comprises: 35-45 parts epoxy resin 20-25 parts of polyacid resin.

3. The multifunctional composite powder coating composition according to claim 1, characterized in that: By weight, the dual-cure cross-linking system comprises: 5-8 parts of amine curing agent; 3-5 parts of isocyanate curing agent.

4. The multifunctional composite powder coating composition according to claim 1, characterized in that: By weight, The composite reinforcement system includes: 3-5 parts of nano silicon dioxide; 2-3 parts of nano-alumina; 0.05-0.2 parts of nanoporous copper-titanium alloy powder; 10-15 parts of titanium dioxide; 5-10 parts of talcum powder.

5. The multifunctional composite powder coating composition according to claim 1 or 4, characterized in that: The nanoporous copper-titanium alloy powder is prepared by a dealloying method, which comprises the following steps: 1) Preparation of Cu-Ti alloy thin films by magnetron sputtering; 2) placing the alloy film in a 0.13-0.2M HF solution and subjecting it to corrosion treatment at 10-30°C for 10-14 hours; 3) The material treated in step 2) is washed and dried to obtain nanoporous copper-titanium alloy powder.

6. The multifunctional composite powder coating composition according to claim 4, characterized in that: The median particle size D50 of titanium dioxide is 0.2-0.8 μm, and the particle size of talc is 10 μm-100 μm.

7. The multifunctional composite powder coating composition according to claim 1, characterized in that: The multifunctional modification system comprises: 1-2 parts of leveling agent; 2-3 parts of toughening agent; 0.5-1 part of ultraviolet absorber; 0.5-1 part of antistatic agent; 2-4 portions of self-repairing microcapsules; 1-2 parts of thermochromic material; 0.5-1 part of antibacterial nanosilver particles; High-efficiency curing accelerator 0.5-1 part.

8. The multifunctional composite powder coating composition according to claim 7, characterized in that: The antistatic agent is a carbon black composite composed of conductive carbon black, epoxy resin and solvent in a mass ratio of (5-7): (2-4): (0.8-1.2); the preparation method of the antistatic agent is as follows: Conductive carbon black and epoxy resin are premixed in proportion, and xylene solvent is added; the mixture is dispersed in a high-speed disperser at 1800-2200 rpm for 25-35 minutes to form a uniform slurry; and a carbon black composite antistatic agent is obtained after vacuum degassing; And / or, the thermochromic material has a color change range of 50-80°C and comprises the following components in parts by weight: 1.0-1.5 parts of crystal violet lactone (coloring agent) Bisphenol A (developer) 0.8-1.2 parts Tetradecanol (solvent) 4.0-5.0 parts 6.0-8.0 parts of an epoxy resin / polyester resin mixture; the mass ratio of the epoxy resin to the polyester resin is 3:2-1:

1. The epoxy resin includes epoxy resin E-12, and the polyester resin includes polyester resin PA-20.

9. A method for preparing the multifunctional composite powder coating composition according to any one of claims 1 to 8, characterized in that: The steps include: (1) Premixing: Add the components of the matrix resin system, dual-cure crosslinking system, composite reinforcement system and multifunctional modification system into a high-speed mixer in proportion, mix at a speed of 1200-1500 rpm for 15-20 minutes under nitrogen protection, and control the material temperature at 10-40°C; (2) Melt extrusion: The premixed material is conveyed to a twin-screw extruder, and the temperature of zone I is set to 80-100°C, the temperature of zone II is set to 110-120°C, and the temperature of zone III is set to 115-125°C. The screw speed is set to 200-400 rpm for melt blending and extrusion; (3) Cooling and tableting: The extrudate is cooled to 25-35°C and pressed into a sheet material with a thickness of 1.5-2.5 mm; (4) Crushing: crush the flake material to a particle size D50 of 30-40 μm at -50°C to -30°C. Powder particles with D90≤60μm; (5) Classification and sieving: The powder is subjected to particle size classification by a turbine airflow classifier, and finished powder with a particle size of 45-75 μm is collected to obtain the multifunctional composite powder coating composition.

10. A plate with a multifunctional composite coating, characterized in that: The structure includes the following stacked structures: a), substrate; b) a primer layer covering the front surface of the substrate, the primer layer being obtained by coating the multifunctional composite powder coating composition according to any one of claims 1 to 8, and having a thickness of 20 to 50 μm; c) a topcoat covering the basecoat, the topcoat being obtained by coating the multifunctional composite powder coating composition according to any one of claims 1 to 8, and having a thickness of 30 to 80 μm; d) a back coating layer covering the base back side, wherein the back coating layer is obtained by coating the multifunctional composite powder coating composition according to any one of claims 1 to 8 and has a thickness of 15 to 40 μm.

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