Special powder coating for super-weather-resistant composite material, and preparation method therefor and coating method therefor

Abstract

The present invention belongs to the technical field of powder coatings. Provided are a special powder coating for a super-weather-resistant composite material, and a preparation method therefor, the use thereof and a coating method therefor. The special powder coating for the super-weather-resistant composite material comprises the following components in percentages by mass: 0-50% of a modified acrylate, 20-75% of a polyester resin, 15-20% of an IPDI adduct, 0.1-0.8% of a texturing agent, 4.3-22.7% of a transparent filling powder, 0.8-1.2% of a pigment, 0.1-0.2% of a toughening agent, 0.1-0.3% of nano aluminum oxide and 0-2% of a conductive agent. The special powder coating for the super-weather-resistant composite material can be applied to a non-conductive composite material, can effectively form firm combination with the surface of the composite material, and is not prone to undergoing a peeling or fall-off phenomenon. In addition, the special powder coating for the super-weather-resistant composite material can achieve low-temperature curing, can satisfy the weather-resistant requirements of outdoor use.

Description

Special powder coating for super-weather-resistant composite material and preparation method and application thereof, and coating method

[0001] The present application claims priority to the Chinese patent application No. CN202410851190.1, filed on June 28, 2024, and entitled "Special powder coating for super-weather-resistant composite material and preparation method and application thereof, and coating method", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of powder coating, in particular to a special powder coating for super-weather-resistant composite material and a preparation method and application thereof, and a coating method. BACKGROUND

[0003] Composite material is a new type of material composed of two or more materials combined by physical or chemical methods. It has excellent properties that single materials cannot match, such as high strength, high stiffness, low density, good dimensional stability, and corrosion resistance, etc. Therefore, it has been widely used in the fields of aerospace, automobile, electronics, construction, etc. However, the surface treatment of composite materials has always been a problem because the surface state of composite materials is very different from that of metal materials, such as low surface energy, large amount of release agent residue on the surface, and uneven surface stress, etc. These factors have a great impact on the effect of surface treatment. Powder coating is a new type of coating suitable for metal surfaces. It is a solid powder-like substance composed of solid resin and pigments, fillers, and additives, etc. It is applied by electrostatic spraying, friction spraying (thermosetting method), or fluidized bed dipping (thermoplastic method), and then heated and melted to form a smooth and bright permanent coating film. Powder coating has the advantages of no solvent pollution, 100% film formation, low energy consumption, simple construction, high efficiency, safety, non-toxicity, convenient storage and transportation, etc.

[0004] The existing technology discloses the application of powder coating to the surface of composite materials, such as using fluidized bed dipping (thermoplastic method), or using spraying method to apply powder on the abrasive or the coated object, heating and pressing the system, and then dipping the powder into the composite material to form a protective film by hot pressing. Although the existing technology solves the problem of applying powder coating to the surface of composite materials to some extent, there are still some problems and shortcomings. For example, the surface state of composite materials is very different from that of metal materials, which leads to poor adhesion of existing powder coatings on the surface of composite materials, and easy peeling or falling off phenomenon.

[0005] SUMMARY

[0006] Therefore, the present application aims to provide a special powder coating for super-weather-resistant composite materials, a preparation method and application thereof, and a coating method.

[0007] To achieve the above-mentioned application purposes, the present application provides the following technical solutions.

[0008] The present application provides a special powder coating for super-weather-resistant composite materials, comprising the following components by mass percentage:

[0009] The modified acrylate is 0-50%, the polyester resin is 20-75%, the adduct of IPDI is 15-20%, the texturing agent is 0.1-0.8%, the transparent filling powder is 4.3-22.7%, the pigment is 0.8-1.2%, the toughening agent is 0.1-0.2%, the nano-aluminum oxide is 0.1-0.3%, and the conductive agent is 0-2%, and the sum of the mass percentages of the components is 100%.

[0010] Preferably, the special powder coating for super-weather-resistant composite materials comprises the following components by mass percentage:

[0011] The modified acrylate is 40-48%, the polyester resin is 20-24%, the adduct of IPDI is 15-18%, the texturing agent is 0.3-0.5%, the transparent filling powder is 7.1-8.2%, the pigment is 1-1.2%, the toughening agent is 0.15-0.2%, the nano-aluminum oxide is 0.1-0.15%, and the conductive agent is 0.3-0.6%.

[0012] Preferably, the special powder coating for super-weather-resistant composite materials comprises the following components by mass percentage:

[0013] The polyester resin is 68-76%, the adduct of IPDI is 15-18%, the texturing agent is 0.3-0.5%, the transparent filling powder is 7.1-8.2%, the pigment is 1-1.2%, the toughening agent is 0.15-0.2%, the nano-aluminum oxide is 0.1-0.15%, and the conductive agent is 0.3-0.6%.

[0014] Preferably, the special powder coating for super-weather-resistant composite materials further comprises a double-layer coated aluminum powder, and the mass percentage of the double-layer coated aluminum powder in the special powder coating for super-weather-resistant composite materials is 0.5-5%.

[0015] Preferably, the particle size of the double-layer coated aluminum powder is 0.5-3 nm, and the double-layer coated aluminum powder is a layered double capsule, which is a non-floating aluminum powder coated with double layers of silicon dioxide and acrylic resin.

[0016] The present application also provides a preparation method of the special powder coating for super-weather-resistant composite materials described in the above technical solutions, comprising the following steps:

[0017] The modified acrylate, the adduct of polyester resin, IPDI, the texturing agent, the transparent filling powder, the pigment, the toughening agent, the nano-alumina and the conductive agent are mixed to obtain the special powder coating for super-weather-resistant composite material.

[0018] Preferably, when the special powder coating for super-weather-resistant composite material further comprises the double-coated aluminum powder, the preparation method further comprises: binding after the mixing.

[0019] The application further provides the application of the special powder coating for super-weather-resistant composite material in the coating of the composite material.

[0020] The application further provides a coating method, comprising the following steps:

[0021] The surface of the composite substrate to be coated is treated to obtain a pretreated composite substrate;

[0022] The pretreated composite substrate is preheated to obtain a preheated substrate, the preheating temperature is 80-170 DEG C, and the preheating time is 6-12 min;

[0023] The surface of the preheated substrate is sequentially sprayed with the powder coating and cured, the powder coating is the special powder coating for super-weather-resistant composite material.

[0024] Preferably, the powder coating further comprises the spraying of the conductive primer before the spraying of the powder coating, the conductive primer is the epoxy resin powder conductive primer, the epoxy polyester conductive primer, the pure polyester powder conductive primer, the polyurethane powder conductive primer or the acrylic powder conductive primer.

[0025] The application provides a special powder coating for super-weather-resistant composite material, comprising the following components by mass percentage: modified acrylate 0-50%, polyester resin 20-75%, adduct of IPDI 15-20%, texturing agent 0.1-0.8%, transparent filling powder 4.3-22.7%, pigment 0.8-1.2%, toughening agent 0.1-0.2%, nano-alumina 0.1-0.3% and conductive agent 0-2%, the sum of the mass percentages of the components is 100%.

[0026] Compared with the prior art, the application has the following beneficial effects:

[0027] Compared with metal substrates, the micro-heterogeneity of the composite material is much worse than that of the metal, and the surface flatness is much worse than that of the metal, which leads to a great influence of the substrate temperature and the formula on the film-forming performance of the powder coating. Due to the uneven heating and the uneven substrate, the existing powder coating cannot form a continuous and uniform film on the composite material, and an excellent coating with excellent appearance and performance cannot be obtained. In the present application, the modified acrylate has low-temperature melting and curing and super-durability, the polyester resin has low-temperature melting and curing and super-durability, the adduct of IPDI is a crosslinking agent for saturated polyester containing hydroxyl groups used in polyurethane powder coating, the texturing agent adjusts the texture state, the transparent filling powder improves the hardness of the coating, the pigment is used for coloring, the toughening agent increases the toughness of the coating, the nano-aluminum oxide promotes the flow performance, and the conductive agent provides the conductive performance. The super-weather-resistant powder coating for composite materials provided in the present application can be applied to non-conductive composite materials, effectively forming a firm bond with the surface of the composite material, and the peeling or falling phenomenon is not easy to occur. The super-weather-resistant powder coating for composite materials provided in the present application can realize low-temperature curing and meet the weathering requirements for outdoor applications.

[0028] Further, the super-weather-resistant powder coating for composite materials provided in the present application further comprises double-coated aluminum powder, and the double-coated aluminum powder is used to ensure the metal flash effect. At this time, a metal flash sand grain powder for composite materials is provided.

[0029] The data of the examples show that the super-weather-resistant powder coating for composite materials provided in the present application can realize excellent adhesion on the surface of the composite material which is difficult to adhere, has a low surface energy, has a release agent residue, and has uneven stress. The coating prepared on the surface of the composite material can pass the cross-cut test and the high-pressure water gun impact test, has excellent wear resistance, meets the extreme use conditions of off-road and special environment vehicles, has excellent fluid resistance and chemical resistance, and has a weather resistance of 4000h under xenon lamp.

[0030] The present application also provides a preparation method of the super-weather-resistant powder coating for composite materials described in the above technical solutions. The binding process is a special mixing procedure, which can solve the adhesion problem between the base powder and the metal pigment, and make the metal pigment and the base powder connected together.

[0031] In the prior art, in the electrostatic spraying system, the spraying gun charges the powder particles, usually with negative charge, and the metal substrate is grounded with positive charge, forming an electrostatic field, the positive charge on the surface of the metal substrate attracts the powder particles with negative charge. When the powder particles are released and sprayed to the surface of the metal substrate by the spraying gun, they are attracted to the metal surface by the electrostatic field, uniformly distributed on the metal surface, quickly adhered to the surface to form a thin film, and the powder particles adsorbed on the metal surface begin to deposit and accumulate to form a continuous powder layer. The application also provides a coating method. The coating method of the application solves the problem of powder spraying process of non-conductive composite materials by using a specific super-weather-resistant composite material special powder coating combined with a preheating process. The use of the super-weather-resistant composite material special powder coating of the application realizes the powder application rate and uniformity on the composite material, and solves the problems of the paint film performance required by the automotive exterior functional assembly, including the rough surface of the composite material, the slight difference in surface state, the shrinkage, pinhole and blistering of the coating after film formation, etc. A coating method is provided, which has high width of the surface state of the coated substrate, can cover the defects of the substrate itself, is suitable for different types of composite materials, can form a flat and defect-free coating on the surface of the composite material; and the obtained coating can realize excellent adhesion on the composite material surface with difficult adhesion, residual release agent, uneven stress, can pass the grid test and high-pressure water gun impact test, the wear resistance meets the extreme use conditions of off-road and special environment vehicles, the fluid and chemical resistance is excellent, and the weather resistance meets the use requirements under extreme conditions. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a whole physical diagram of the coating obtained from the super-weather-resistant composite material special powder coating of Example 6;

[0033] Figure 2 is a partially enlarged view of the coating obtained from the super-weather-resistant composite material special powder coating of Example 6;

[0034] Figure 3 is a whole physical diagram of the coating obtained from the super-weather-resistant composite material special powder coating of Example 7;

[0035] Figure 4 is a partially enlarged view of the coating obtained from the super-weather-resistant composite material special powder coating of Example 7;

[0036] Figure 5 is a physical diagram of Comparative Example 2;

[0037] Figure 6 is a physical diagram of Comparative Example 3;

[0038] Figure 7 is a physical diagram of Comparative Example 4;

[0039] Figure 8 is a physical diagram of Comparative Example 5;

[0040] Figure 9 is a physical diagram of Comparative Example 6;

[0041] Fig. 10 is a physical diagram of Comparative Example 7;

[0042] Fig. 11 is a physical diagram of Comparative Example 8;

[0043] Fig. 12 is a physical diagram of Comparative Example 9;

[0044] Fig. 13 is a physical diagram of Comparative Example 10. DETAILED DESCRIPTION

[0045] The application provides a special powder coating for super-weather-resistant composite materials, which comprises the following components by mass percentage:

[0046] 0-50% of modified acrylate, 20-75% of polyester resin, 15-20% of adduct of IPDI, 0.1-0.8% of texturing agent, 4.3-22.7% of transparent filling powder, 0.8-1.2% of pigment, 0.1-0.2% of toughening agent, 0.1-0.3% of nano-aluminum oxide and 0-2% of conductive agent, and the sum of the mass percentages of the components is 100%.

[0047] In the application, the raw materials used are commercially available in the art unless otherwise specified.

[0048] The mass fraction of the modified acrylate in the special powder coating for super-weather-resistant composite materials provided by the application is preferably 40-48%, and the modified acrylate has low-temperature melting and curing and super-strong durability.

[0049] In the application, the modified acrylate is preferably polyurethane acrylate or epoxy acrylate.

[0050] In the application, the epoxy acrylate is preferably an epoxy-type acrylate powder coating resin, which can be prepared by referring to the method disclosed in CN115651473A.

[0051] In the application, the preparation method of the polyurethane acrylate preferably comprises the following steps:

[0052] The isocyanate, the polyester polyol, the acrylic monomer with a hydroxyl group and the organic solvent are mixed to perform a prepolymerization reaction to obtain a polyurethane prepolymer.

[0053] The polyurethane prepolymer, the terminal double-bond-containing silane, the acrylate monomer, the initiator, the chain transfer agent and the organic solvent are mixed to perform a free radical polymerization reaction to obtain the polyurethane acrylate.

[0054] In the application, the raw materials used are commercially available in the art unless otherwise specified.

[0055] In the application, the isocyanate, the polyester polyol, the acrylic monomer with a hydroxyl group and the organic solvent are mixed to perform a prepolymerization reaction to obtain a polyurethane prepolymer.

[0056] In the present application, the molar ratio of the isocyanate, the polyester polyol and the hydroxyl group-containing acrylic monomer is preferably 1:0.5:0.5-1:0.3:1.2, more preferably 1:0.5:1.

[0057] In the present application, the hydroxyl group-containing acrylic monomer preferably includes one or more of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate.

[0058] In the present application, the isocyanate preferably includes one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenyl methane diisocyanate and dicyclohexyl methane diisocyanate.

[0059] In the present application, the polyester polyol preferably includes polycarbonate polyol and / or polycaprolactone polyol.

[0060] In the present application, the organic solvent preferably includes one or more of DMF, xylene and PMA, and the present application does not have special limitation on the kind of the organic solvent, which can ensure complete dissolution of raw materials.

[0061] In the present application, the temperature of the prepolymerization is preferably 85-95°C, more preferably 90°C, and the time is preferably 3-4h.

[0062] After obtaining the polyurethane prepolymer, the present application mixes the polyurethane prepolymer, the terminal double-bond-containing silane, the acrylate monomer, the initiator, the chain transfer agent and the organic solvent to perform a free radical polymerization reaction, thereby obtaining the polyurethane acrylate.

[0063] In the present application, the molar ratio of the polyurethane prepolymer, the terminal double-bond-containing silane and the acrylate monomer is preferably 1:0.3:4-1:2:12, more preferably 3:1:16, 3:3:14 or 1:2:12.

[0064] In the present application, the terminal double-bond-containing silane preferably includes one or more of terminal vinyl group-containing silane, terminal acrylic acid-containing silane, terminal acryloyloxy group-containing silane and terminal methacryl group-containing silane, the terminal vinyl group-containing silane is preferably the terminal acrylic acid-containing silane is preferably Japan Shin-Etsu KBM-503, the terminal acryloyloxy group-containing silane is preferably Japan Shin-Etsu KBM5103, and the terminal methacryl group-containing silane is preferably Japan Shin-Etsu KBM5803.

[0065] In the present application, the acrylate monomer preferably includes one or more of methyl methacrylate, styrene, butyl acrylate, butyl methacrylate, acrylic acid, glycidyl methacrylate, isobornyl methacrylate, vinyl versatate, cyclohexyl methacrylate, (meth)acrylic acid-modified polycaprolactone, ethyl acrylate and ethylene glycol dimethacrylate.

[0066] In the present application, the initiator is preferably a peroxide, more preferably dibenzoyl peroxide BPO, di-t-butyl peroxide or di-t-amyl peroxide.

[0067] In the present application, the molar ratio of the polyurethane prepolymer to the initiator is preferably 1:0.05-1:1, more preferably 3:0.43, 1:0.33 or 3:0.23.

[0068] In the present application, the chain transfer agent is preferably n-dodecyl mercaptan.

[0069] In the present application, the molar ratio of the polyurethane prepolymer to the chain transfer agent is preferably 1:0.02-1:1, more preferably 1:0.05, 1:0.1 or 3:0.1.

[0070] In the present application, the organic solvent preferably includes one or more of xylene, PMA, toluene, ethylene glycol n-butyl ether and solvent oil, and the present application does not have special limitation on the type of the organic solvent, which can only ensure complete dissolution of raw materials.

[0071] In the present application, the temperature of the free radical polymerization reaction is preferably 100-140°C, more preferably 130-135°C, and the time is preferably 4-7h.

[0072] In the present application, the organic solvent is preferably preheated to the reaction temperature, the acrylate monomer and the chain transfer agent are mixed uniformly to obtain a mixed solution, and then the mixed solution and the initiator are separately and uniformly dropped into the preheated organic solvent, when 1 / 3 of the mass of the mixed solution remains, the polyurethane prepolymer and the terminal double-bond silane are further dropped, and the free radical polymerization reaction is carried out, and the initiator is preferably supplemented during the free radical polymerization reaction.

[0073] After the free radical polymerization reaction is completed, the solvent is removed by vacuumizing, and the product is discharged while hot to obtain the polyurethane acrylate.

[0074] In the present application, the mass fraction of the polyester resin is preferably 20-24% when the mass fraction of the modified acrylate in the special powder coating for super-weather-resistant composite material is not 0, and the mass fraction of the polyester resin is preferably 68-76% when the mass fraction of the modified acrylate in the special powder coating for super-weather-resistant composite material is 0. The polyester resin has a relatively low glass transition temperature, and is matched with the polyurethane acrylate to balance the melt flow performance in each temperature region and provide certain durability.

[0075] In the present application, the polyester resin is preferably a saturated carboxyl polyester resin.

[0076] The mass percentage of the adduct of IPDI in the special powder coating for super-weather-resistant composite material provided in the present application is preferably 15-18%, and the adduct of IPDI is a crosslinking agent for the hydroxyl-containing saturated polyester used in the polyurethane powder coating.

[0077] In the present application, the adduct of IPDI is preferably B 1530.

[0078] The mass percentage of the texturing agent in the special powder coating for super-weather-resistant composite material provided in the present application is preferably 0.3-0.5%, and the texturing agent is used to adjust the texture state.

[0079] In the present application, the texturing agent is preferably SW301 (Nanhai Chemical SW301) purchased from Foshan Nanhai 113 Chemical Co., Ltd.

[0080] The mass percentage of the transparent filling powder in the special powder coating for super-weather-resistant composite material provided in the present application is preferably 7.1-8.2%, and more preferably 7.6-7.9%, and the transparent filling powder is used to improve the hardness of the coating.

[0081] In the present application, the median particle size of the transparent filling powder is preferably 3.5 nm.

[0082] In the present application, the composite nano-silicon is preferably MINEX-7.

[0083] The mass percentage of the pigment in the special powder coating for super-weather-resistant composite material provided in the present application is preferably 1-1.2%, and the pigment is used for coloring.

[0084] In the present application, the pigment is preferably ORION COLOUR BLACK FW200.

[0085] The mass percentage of the toughening agent in the special powder coating for super-weather-resistant composite material provided in the present application is preferably 0.15-0.2%, and the toughening agent is used to improve the toughness of the coating.

[0086] In the present application, the flexibilizer is preferably MOWITAL B60H.

[0087] The mass percentage of nano-alumina in the special powder coating for super-weather-resistant composite material provided in the present application is preferably 0.1-0.15%, and the nano-alumina serves to promote the flowability.

[0088] In the present application, the nano-alumina is preferably AEROXIDE ALU-C.

[0089] The mass percentage of conductive agent in the special powder coating for super-weather-resistant composite material provided in the present application is preferably 0.3-0.6%, and the conductive agent serves to make the powder conductive, improve the powdering property, and make the appearance of the sprayed paint film completely consistent, which can meet the application fields with extremely high requirements for the consistency of product appearance, such as consumer product outer finish and automobile A-level surface.

[0090] In the present application, the conductive agent is preferably BC-L15 inorganic equalizing agent purchased from Shanghai Junjiang New Material Sales Co., Ltd.

[0091] In the present application, the special powder coating for super-weather-resistant composite material preferably comprises the following components in the following mass percentages:

[0092] modified acrylate 40-48%, polyester resin 20-24%, adduct of IPDI 15-18%, texture agent 0.3-0.5%, transparent filling powder 7.1-8.2%, pigment 1-1.2%, flexibilizer 0.15-0.2%, nano-alumina 0.1-0.15%, and conductive agent 0.3-0.6%, or comprises the following components in the following mass percentages:

[0093] polyester resin 68-76%, adduct of IPDI 15-18%, texture agent 0.3-0.5%, transparent filling powder 7.1-8.2%, pigment 1-1.2%, flexibilizer 0.15-0.2%, nano-alumina 0.1-0.15%, and conductive agent 0.3-0.6%.

[0094] In the present application, the special powder coating for super-weather-resistant composite material preferably further comprises double-coated aluminum powder, and the mass percentage of the double-coated aluminum powder in the special powder coating for super-weather-resistant composite material is preferably 0.5-5%, more preferably 0.5-3%, and the double-coated aluminum powder can provide a metallic flash effect.

[0095] In the present application, the particle size of the double-coated aluminum powder is preferably 0.5-3 nm, and the double-coated aluminum powder is preferably a layered double capsule, preferably a non-floating aluminum powder double-coated with silicon dioxide and acrylic resin.

[0096] In the present application, the double-coated aluminum powder is preferably ECKART PCU 1500.

[0097] The present application also provides a preparation method of the special powder coating for super-weather-resistant composite materials.

[0098] The modified acrylate, the adduct of polyester resin and IPDI, the texturing agent, the transparent filling powder, the pigment, the toughening agent, the nano-aluminum oxide and the conductive agent are mixed to obtain the special powder coating for super-weather-resistant composite materials.

[0099] The present application does not have special limitations on the specific way of mixing, and the way known to those skilled in the art can be used.

[0100] In the present application, when the special powder coating for super-weather-resistant composite materials preferably further comprises a double-coated aluminum powder, the preparation method preferably further comprises binding after the mixing.

[0101] In the present application, the parameters of the binding preferably include a temperature of 60-70 DEG C, and the binding is used to solve the adhesion problem between the base powder and the metal pigment, so that the metal pigment is connected with the base powder.

[0102] In the present application, the mixing preferably further comprises sequentially performing melt extrusion, tabletting and cooling, primary crushing, grinding and sieving to obtain the special powder coating for super-weather-resistant composite materials.

[0103] The present application also provides the application of the special powder coating for super-weather-resistant composite materials in the coating of composite materials.

[0104] The present application also provides a coating method, comprising the following steps:

[0105] The surface of the composite substrate to be coated is treated to obtain a pretreated composite substrate.

[0106] The pretreated composite substrate is preheated to obtain a preheated substrate, and the preheating temperature is 80-170 DEG C and the preheating time is 6-12 min.

[0107] The surface of the preheated substrate is sequentially sprayed with a powder coating and cured, and the powder coating is the special powder coating for super-weather-resistant composite materials described in the above technical solution.

[0108] The present application treats the surface of the composite substrate to be coated to obtain a pretreated composite substrate.

[0109] In the present application, the composite substrate is preferably made of lightweight low-density composite material, and more preferably is the roof of an off-road vehicle.

[0110] In the present application, the surface treatment preferably comprises cleaning and degreasing in sequence to ensure that the surface is smooth and free of grease and other contaminants.

[0111] In the present application, the degreasing preferably uses isopropyl alcohol.

[0112] After obtaining the pretreated composite substrate, the present application preheats the pretreated composite substrate to obtain a preheated substrate, and the preheating temperature is 80-170°C and the time is 6-12 min.

[0113] In the present application, the preheating temperature is preferably 100-150°C, more preferably 120-140°C, and the time is preferably 8-10 min.

[0114] After obtaining the preheated substrate, the present application sprays and cures powder coating on the surface of the preheated substrate in sequence, and the powder coating is the special powder coating for super-weather-resistant composite materials as described in the above technical solution.

[0115] In the present application, the spraying gun used in the spraying is preferably set according to the different shapes of the workpiece, and when the workpiece is preferably a flat plate part, the voltage of the spraying is preferably 80 kV and the current is preferably 30 μA; when the workpiece is preferably a complex part with grooves, the voltage of the spraying is preferably 80 kV and the current is preferably 22 μA; when the spraying is preferably re-coating, the voltage of the spraying is preferably 40 kV and the current is preferably 30 μA.

[0116] In the present application, the preheating spraying temperature is preferably 80-170°C, more preferably 80-130°C, and most preferably 90-110°C.

[0117] In the present application, the distance, the spraying angle and the speed of the spraying gun from the surface of the preheated substrate are properly ensured during the spraying to ensure the uniformity and quality of the coating.

[0118] When the special powder coating for super-weather-resistant composite materials does not include inorganic equalizing agents, the spraying is preferably one-time continuous spraying of multiple paint films (at this time, the powder application principle is thermal adsorption), and then the curing is performed; when the special powder coating for super-weather-resistant composite materials includes inorganic equalizing agents, the spraying is preferably thin spraying of one paint film (at this time, the powder application principle is thermal adsorption, and this paint film changes the non-conductive composite material into a conductive metal-like substrate, so that the powder application and the paint film appearance are not easy to be uneven as the metal substrate); the sprayed special powder coating for super-weather-resistant composite materials is self-conductive, the workpiece temperature is reduced to below 90°C, multiple paint films are sprayed to meet the film thickness requirement (at this time, the powder application principle is electrostatic adsorption), and then the curing is performed.

[0119] In the present application, the temperature of the solidification is preferably 160-180℃, and the time is preferably 7-20min.

[0120] In the present application, taking the film thickness of 60-90μm as an example, a recovery system is preferably provided during the spraying, and the amount of the super-weather-resistant composite material special powder coating is preferably 6-10m 2 / kg without the recovery system, and the amount of the super-weather-resistant composite material special powder coating is preferably 5-6m 2 / kg.

[0121] In the present application, the powder coating preferably further includes the spraying of a conductive primer before the spraying of the powder coating, and the conductive primer is preferably an epoxy resin powder conductive primer, an epoxy polyester conductive primer, a pure polyester powder conductive primer, a polyurethane powder conductive primer, or an acrylic powder conductive primer.

[0122] In the present application, the epoxy resin powder conductive primer preferably includes the following components in mass percentage: bisphenol A epoxy resin 48%, cyclic aliphatic amine modified curing agent 12%, dimethyl imidazole 1%, benzoin 3%, CaSiO326%, pigment 8%, inorganic equalizing agent 2%, the bisphenol A epoxy resin is preferably Nan Ya Epoxy Resin NPES 902, the cyclic aliphatic amine modified curing agent is preferably Epokukdo KD-420, the pigment is preferably ORION COLOUR BLACK FW200, and the inorganic equalizing agent is preferably BC-L15.

[0123] The present application does not have special limitations on the preparation method of the conductive primer, and any method known to those skilled in the art can be used.

[0124] The technical solutions in the present application will be described clearly and completely below in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0125] The preparation method of the polyurethane acrylate used in the embodiments is as follows:

[0126] Take 1mol of hexamethylene diisocyanate, 1.0mol of hydroxyethyl methacrylate, 0.5mol of polycarbonate polyol, and dimethylbenzene, mix them, and perform pre-polymerization at 85℃ for 4h to obtain a polyurethane prepolymer;

[0127] Xylene is preheated to 100℃, methyl methacrylate 0.5mol, butyl acrylate 0.1mol, glycidyl methacrylate 0.3mol, styrene 0.1mol, isobornyl methacrylate 0.1mol and dodecyl mercaptan 0.01mol are mixed uniformly to obtain a mixed solution; the mixed solution and initiator BPO 0.03mol are added into the preheated xylene at a uniform speed, the mixed solution is added for 3h, and the initiator is added for 3.5h. Then when 1 / 3 of the mass of the mixed solution remains, 0.2mol is added to the reaction system for 1.5h. Then free radical polymerization is carried out at 100℃ for 7.9h. 0.003mol of initiator is added again, and the reaction is kept for 1h. After the reaction is completed, vacuum is started until all the solvent is removed, and finally the material is discharged while hot to obtain a polyurethane acrylate.

[0128] Preparation of epoxy acrylate: refer to Example 1 in CN115651473A.

[0129] Example

[0130] The raw material composition of the special powder coating for super-weather-resistant composite materials provided in the application is shown in Table 1.

[0131] The preparation method of the special powder coating for super-weather-resistant composite materials in the example comprises the following steps:

[0132] After mixing the raw materials, melt extrusion, tablet cooling, primary crushing, grinding and sieving are sequentially performed to obtain the special powder coating for super-weather-resistant composite materials. When the special powder coating for super-weather-resistant composite materials further comprises double-coated aluminum powder, binding (70℃) is performed after mixing is completed.

[0133] Coating is performed on the roof of an off-road vehicle, comprising the following steps:

[0134] Pre-treatment: surface treatment is performed on the substrate to be coated, including cleaning and oil removal (wiping with isopropyl alcohol);

[0135] The spray gun is set according to the different shapes of the workpiece, and for flat plate parts, the voltage is 80kV and the current is 30μA;

[0136] Preheating: temperature 130℃, time 10min, spraying temperature 95℃;

[0137] Spraying: the powder coating is uniformly sprayed on the surface of the substrate by the spraying equipment, and there is a recycling system during spraying. The amount of the special powder coating for super-weather-resistant composite materials used is 10m 2 / g (Examples 1-5 are non-conductive powders, which need to be completely used in the thermal spraying process, and a plurality of paint films are sprayed in one time and continuously, and then solidified, and Examples 6 and 7 are conductive powders, which are first sprayed in one thin paint film, and then a plurality of paint films are sprayed after the workpiece temperature is reduced to below 90℃ to reach the film thickness requirement)

[0138] Solidification: temperature 180℃, time 20min.

[0139] Table 1 Raw material composition of the special powder coating for super weather-resistant composite materials (wt%)

[0140] The performance of the obtained coating was tested, and the results are shown in Table 2. It can be seen that the performance of Examples 6 and 7 is the best, and the powder itself is conductive after adding BC-L15, which is easier to spray and completely solves the problem of mottling.

[0141] Table 2 Test results of coating performance

[0142] Figure 1 is a whole physical diagram of the coating obtained from the special powder coating for super weather-resistant composite materials of Example 6, and Figure 2 is a diagram after local magnification.

[0143] Figure 3 is a whole physical diagram of the coating obtained from the special powder coating for super weather-resistant composite materials of Example 7, and Figure 4 is a diagram after local magnification. As can be seen from Figures 1-4, the coating obtained from the special powder coating for super weather-resistant composite materials of Examples 6 and 7 has a smooth appearance and completely consistent texture.

[0144] Comparative Example 2

[0145] The special powder coating for super weather-resistant composite materials prepared in Example 6 was used for spraying, and the substrate was not preheated, and the physical diagram is shown in Figure 5. It can be seen that the powder coating cannot be hung on the surface of the substrate without preheating.

[0146] Comparative Example 3

[0147] The special powder coating for super weather-resistant composite materials prepared in Example 6 was used for spraying, and the preheating temperature of the substrate was 60℃, and the physical diagram is shown in Figure 6. It can be seen that the powder cannot completely cover the substrate due to poor powdering.

[0148] Comparative Example 4

[0149] The special powder coating for super weather-resistant composite materials prepared in Example 6 was used for spraying, and the preheating temperature of the substrate was 70℃, and the physical diagram is shown in Figure 7. It can be seen that the problem of uneven powdering easily occurs.

[0150] Comparative Example 5

[0151] The super weather-resistant composite special powder coating prepared in Example 6 was used for spraying, and the preheating temperature of the substrate was 180°C. As shown in FIG. 8, it can be seen that the preheating temperature was high, the powder did not flow on the substrate quickly, and the appearance was inconsistent due to the rapid reaction and curing.

[0152] Comparative Example 6

[0153] The super weather-resistant composite special powder coating prepared in Example 6 was used for spraying, and the powder spraying film thickness was too thin. As shown in FIG. 9, the actual figure.

[0154] Comparative Example 7

[0155] The super weather-resistant composite special powder coating prepared in Example 6 was used for spraying, and the powder spraying spraying pass number was small. As shown in FIG. 10, the actual figure.

[0156] Comparative Example 8

[0157] The super weather-resistant composite special powder coating prepared in Example 6 was used for spraying, and the powder spraying substrate temperature was not uniform. As shown in FIG. 11, the actual figure.

[0158] As shown in FIGS. 9-11, film thickness is too thin, spraying pass number is small, and substrate temperature is not uniform, which can cause the powder to melt and flow better at a higher substrate temperature than at a lower temperature, causing local brightening.

[0159] Comparative Example 9 (conductive liquid + preheating process)

[0160] Pre-treatment: surface treatment of the substrate to be coated, including cleaning, oil removal (wiping with isopropyl alcohol);

[0161] Spray conductive liquid: use an air spray gun to uniformly spray BC-S01 water-based conductive liquid (Shanghai Junjiang New Materials) on the workpiece, with a film thickness of 20 μm;

[0162] Conductive liquid drying: 100°C, 5 min drying;

[0163] The spray gun is set according to the different shapes of the workpiece. For flat plate parts, the voltage is 80 kV and the current is 30 μA.

[0164] Preheating: temperature 140°C, time 10 min, spraying temperature 110°C;

[0165] Spraying: uniformly spray the powder coating of Example 6 on the surface of the substrate by spraying equipment. A recycling system is provided during spraying, and the amount of super weather-resistant composite special powder coating used is 10 m 2 / kg;

[0166] Curing: temperature 180°C, time 20 min.

[0167] The obtained coating is shown in Figure 12, and the surface coating of the process is substantially uniform. It is necessary to pay attention to the uniformity of the conductive liquid spraying and the film thickness control, and not too thick, so as to avoid causing uneven traces of the conductive liquid.

[0168] Comparative Example 10 (spraying process of static agent at room temperature)

[0169] Pre-treatment: surface treatment is performed on the substrate to be coated, including cleaning, oil removal (wiping with isopropanol);

[0170] Spraying of static agent: pw-5100 aqueous conductive crosslinking agent is uniformly sprayed on the workpiece using an air spray gun, and the film thickness is 20 μm;

[0171] The substrate is dried using an air gun;

[0172] Spraying: the powder coating of Example 6 is uniformly sprayed on the surface of the substrate by a spraying device, and a recycling system is used during spraying. The amount of super-weather-resistant composite special powder coating is 10 m 2 / kg; it is necessary to ensure that the distance, spraying angle and speed of the spraying gun from the surface of the substrate are appropriate, so as to ensure the uniformity and quality of the coating;

[0173] Curing: 180℃, time 20 min.

[0174] The obtained coating is shown in Figure 13, and the surface coating of the process is substantially uniform.

[0175] In summary, the performance summary comparison of the super-weather-resistant composite special powder coating of the present application and the conventional powder coating is shown in Table 3.

[0176] Table 3 Performance summary comparison of the super-weather-resistant composite special powder coating of the present application and the conventional powder coating

[0177] Example 10 Conductive base powder

[0178] The composition is shown in Table 4.

[0179] Table 4 Composition of conductive base powder

[0180] Spraying process (base powder + surface powder, two coatings and one baking):

[0181] Pre-treatment: surface treatment is performed on the substrate to be coated, including cleaning, oil removal (wiping with isopropanol);

[0182] The spraying gun is set according to the different shapes of the workpiece. For flat plate parts, the voltage is 80 kV and the current is 30 μA;

[0183] Preheating: temperature 140℃, time 10 min, spraying temperature 110℃;

[0184] Spraying conductive primer: through the spraying equipment, the conductive primer is evenly sprayed on the surface of the substrate, and a thin film of paint is sprayed, at this time the powder mechanism is thermal adsorption;

[0185] Spraying of face powder (Examples 1-9): after spraying the conductive primer, the temperature of the workpiece is reduced to below 90°C, and then a plurality of special powder coatings for super weather-resistant composite materials are sprayed, and the film thickness requirement is reached, at this time the powder mechanism is electrostatic adsorption;

[0186] Curing: temperature 180°C, time 20 min.

[0187] The test results of the coating are shown in Table 5.

[0188] Table 5 Test results of the two-coat-one-bake coating performance

[0189] The above only describes the preferred embodiments of the present application, and does not limit the present application in any form. It should be noted that for ordinary skilled persons in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A powder coating for superdurable composites, characterized in that, Components comprising the following mass percentages: Modified acrylate 0-50%, polyester resin 20-75%, adduct of IPDI 15-20%, texturing agent 0.1-0.8%, transparent filling powder 4.3-22.7%, pigment 0.8-1.2%, toughening agent 0.1-0.2%, nano-alumina 0.1-0.3% and conductive agent 0-2%, the sum of the mass percentages of each component being 100%.

2. The superdurable composite special powder paint according to claim 1, characterized in that, Components comprising the following mass percentages: Modified acrylate 40-48%, polyester resin 20-24%, adduct of IPDI 15-18%, texturing agent 0.3-0.5%, transparent filling powder 7.1-8.2%, pigment 1-1.2%, toughening agent 0.15-0.2%, nano-alumina 0.1-0.15% and conductive agent 0.3-0.6%.

3. The superdurable composite special powder paint according to claim 1 or 2, characterized in that, The modified acrylate is a polyurethane acrylate or an epoxy acrylate.

4. The superdurable composite special powder paint according to claim 3, characterized in that, The preparation method of the polyurethane acrylate comprises the following steps: Mixing isocyanate, polyester polyol, hydroxyl-containing acrylic monomer and organic solvent to perform prepolymerization to obtain a polyurethane prepolymer; Mixing the polyurethane prepolymer, terminal double-bond-containing silane, acrylate monomer, initiator, chain transfer agent and organic solvent to perform free radical polymerization to obtain the polyurethane acrylate.

5. The superdurable composite special powder paint according to claim 4, characterized in that, The molar ratio of the isocyanate, polyester polyol and hydroxyl-containing acrylic monomer is 1:0.5:0.5-1:0.3:1.

2.

6. The superdurable composite special powder paint according to claim 4 or 5, characterized in that, The hydroxyl-containing acrylic monomer comprises one or more of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate.

7. The superdurable composite special powder paint according to claim 4, characterized in that, The molar ratio of the polyurethane prepolymer, terminal double-bond-containing silane and acrylate monomer is 1:0.3:4-1:2:

12.

8. The superdurable composite special powder paint according to claim 1, characterized in that, Components comprising the following mass percentages: Polyester resin 68-76%, adduct of IPDI 15-18%, texturing agent 0.3-0.5%, transparent filling powder 7.1-8.2%, pigment 1-1.2%, toughening agent 0.15-0.2%, nano-alumina 0.1-0.15% and conductive agent 0.3-0.6%.

9. The superdurable composite special powder paint according to claim 1, characterized in that, It also comprises double-layer coated aluminum powder, and the mass percentage of the double-layer coated aluminum powder in the special powder coating for super-weather-resistant composite materials is 0.5-5%.

10. The superdurable composite special powder paint according to claim 9, characterized in that, The particle size of the double-layer coated aluminum powder is 0.5-3 nm, and the double-layer coated aluminum powder is a layered double capsule, which is a non-floating aluminum powder coated with double layers of silicon dioxide and acrylic resin.

11. A process for the preparation of the special powder coating for superdurable composites according to any one of claims 1 to 8, characterized in that, Comprising the following steps: Mixing modified acrylate, polyester resin, adduct of IPDI, texturing agent, transparent filling powder, pigment, toughening agent, nano-alumina and conductive agent to obtain the special powder coating for super-weather-resistant composite materials.

12. The method of claim 11, wherein, When the special powder coating for super-weather-resistant composite materials further comprises double-layer coated aluminum powder, the preparation method further comprises: binding after the mixing.

13. The method of claim 12, wherein, The temperature of the binding is 60-70°C.

14. Use of the special powder coating for super-weather-resistant composite materials according to any one of claims 1-10 in coating of composite materials.

15. A painting method characterized by, Comprising the following steps: Performing surface treatment on a composite substrate to be coated to obtain a pretreated composite substrate; Preheating the pretreated composite substrate to obtain a preheated substrate, the preheating temperature is 80-170 DEG C, the time is 6-12 min; Spraying and curing powder coating on the surface of the preheated substrate in sequence, the powder coating is the special powder coating for ultra-weatherable composite material according to any one of claims 1-10.

16. The painting method according to claim 15, characterized by The spraying gun is set according to the different shapes of the workpiece, when the workpiece is a flat plate part, the voltage of the spraying is 80 kV, the current is 30 mu A; when the workpiece is a complex part with grooves, the voltage of the spraying is 80 kV, the current is 22 mu A.

17. The painting method according to claim 15, characterized by The curing temperature is 160-180 DEG C, the time is 7-20 min.

18. The painting method according to claim 15, characterized by, The spraying of the powder coating further includes spraying a conductive primer, the conductive primer is an epoxy resin powder conductive primer, an epoxy polyester conductive primer, a pure polyester powder conductive primer, a polyurethane powder conductive primer or an acrylic powder conductive primer.

19. The painting method according to claim 18, characterized by The epoxy resin powder conductive primer includes the following components by mass percentage: bisphenol A epoxy resin 48%, cyclic aliphatic amine modified curing agent 12%, dimethyl imidazole 1%, benzoin 3%, CaSiO3 26%, pigment 8%, inorganic equalizing agent 2%.

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