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CN-121991577-A - Microbead modified corrosion-resistant dry-plated metal powder coating material and preparation method thereof

CN121991577ACN 121991577 ACN121991577 ACN 121991577ACN-121991577-A

Abstract

The invention relates to the technical field of coating material preparation, in particular to a microbead modified corrosion-resistant dry-plated metal powder coating material and a preparation method thereof. The powder coating material has the advantages of keeping the metal appearance and construction stability, remarkably improving corrosion resistance and durability, along with strong interface bonding of a coating film, few pore channels, effectively inhibiting foaming, pitting and corrosive medium permeation along the interface in a salt spray environment, reducing the corrosion rate along scratch expansion and prolonging service life after the scratch or the microcrack is formed, along with uniform powder charging, high powder coating rate, more uniform film thickness distribution, stable dry plating metal effect and small recycling chromatic aberration fluctuation, and is suitable for protecting and coating the metal base materials with the requirements on the appearance and corrosion resistance.

Inventors

  • QIAN JIAN
  • FAN JIHUA

Assignees

  • 张家港市卓华金属科技有限公司

Dates

Publication Date
20260508
Application Date
20260320

Claims (10)

  1. 1. 55-65 Parts of carboxyl polyester resin, 6-14 parts of epoxy resin, 0.2-0.8 part of curing accelerator, 0.8-1.5 parts of flatting agent, 0.2-0.6 part of degasifying agent, 10-20 parts of pigment filler, 2-8 parts of brush polymer modified microbeads, 3-10 parts of metal pigment, 0.15-0.6 part of dry plating binder and 0.05-0.3 part of charge regulating auxiliary agent; The brush-shaped polymer modified microbeads are composite particles taking solid glass microbeads as cores, the surfaces of the brush-shaped polymer modified microbeads are anchored with surface initiation sites through silanization, and polymer brush layers are grown on the surfaces of the glass microbeads in situ through surface initiation controllable free radical polymerization, wherein the polymer brush layers at least comprise: A, a resin-philic reaction section containing glycidyl methacrylate structural units; and B, a functional section containing a low surface energy monomer structural unit and a disulfide bond dynamic covalent bond structural unit.
  2. 2. The bead-modified corrosion-resistant dry-plated metal powder coating material according to claim 1, wherein the solid glass beads have a D50 of 10-30 μm.
  3. 3. The bead modified corrosion resistant dry plated metal powder coating material according to claim 1, wherein the mass ratio of glycidyl methacrylate, low surface energy monomer, disulfide bond containing monomer in the monomer system used to form the polymer brush layer is 20-45:5-20:2-10.
  4. 4. The bead-modified corrosion-resistant dry metal powder coating material of claim 3, wherein said low surface energy monomer is selected from one or more of a siloxane acrylate, a fluoroalkylacrylate, and said disulfide-containing monomer is selected from one or more of a bis (2-methacryloxyethyl) disulfide, a bis (2-acryloxyethyl) disulfide, a cystamine di (meth) acrylate, and a cystamine di (meth) acrylamide.
  5. 5. The microbead modified corrosion-resistant dry-plated metal powder coating material according to claim 1, wherein the curing accelerator is selected from one or more of triphenylphosphine, tetraphenylphosphine bromide, 1-methylimidazole, 2-phenylimidazole, dimethylimidazoline, 2,4, 6-tris (dimethylaminomethyl) phenol, tertiary amine accelerators, the leveling agent is selected from one or more of acrylate leveling agents, polysiloxane modified leveling agents, fluorine modified leveling agents, the degassing agent is selected from one or more of benzoin, benzoin and ether derivatives thereof, caprolactam, benzamide degassing agents, and the charge regulating auxiliary is selected from one or more of quaternary ammonium salts, quaternary phosphonium salts, organic sulfonic acid salts, metal-organic complexes, and polyether modified/siloxane modified charge regulators.
  6. 6. The microbead modified corrosion-resistant dry-plated metal powder coating material according to claim 1, wherein the pigment filler is one or more selected from titanium pigment, iron oxide red, phthalocyanine blue, phthalocyanine green, ultramarine, carbon black, chrome green oxide, barium sulfate, calcined kaolin, talcum powder and precipitated silicate, the metal pigment is one or more selected from flaky aluminum silver powder, coated aluminum silver powder, pearlescent aluminum powder, stainless steel metal pigment and nichrome metal pigment, and the dry-plated binder is one or more selected from polyester binders, acrylic binders, ethylene-vinyl acetate copolymer binders and polyamide binders.
  7. 7. A method for preparing a microbead-modified corrosion-resistant dry-plated metal powder coating material, which is used for preparing the microbead-modified corrosion-resistant dry-plated metal powder coating material according to any one of claims 1 to 6, and is characterized by comprising the following steps: S1, anchoring the surfaces of the microbeads, namely washing solid glass microbeads, drying at 80-110 ℃ for 0.5-2 h, dispersing the solid glass microbeads in an alcohol/ester mixed solvent, adding a silane coupling agent, adding water accounting for 0.3-2.0 vol% of the total volume of the solvent, regulating the pH value of a system to 4.0-5.5 by using glacial acetic acid, reacting at 50-80 ℃ for 2-6 h, filtering and washing with ethanol for 2-3 times after the reaction is finished, and drying at 50-70 ℃ for 2-6 h in vacuum to obtain microbeads with anchoring sites on the surfaces; S2, dispersing the microbeads obtained in the step S1 in an ethanol/water mixed solvent, wherein the volume fraction of the ethanol is 70-90%, the mass fraction of the microbeads is 5-20%, adding a chain transfer agent and a photocatalyst into the suspension system, adopting surface-initiated controllable free radical polymerization to grow a polymer brush layer on the surface of the microbeads, forming the total concentration of a monomer system of the polymer brush layer to be 10-35% of the mass fraction of the solvent, adopting a stage feeding mode to construct a gradient brush layer, namely, enriching and polymerizing glycidyl methacrylate monomer, introducing a low-surface energy monomer and a disulfide bond-containing monomer, wherein the polymerization temperature is 25-75 ℃, the reaction time is 2-8 h, and after the reaction is finished, carrying out solid-liquid separation, washing 2-3 times by ethanol and drying 4-10 h under the vacuum condition of 50-70 ℃ to obtain brush-shaped polymer modified microbeads; S3, preparing base powder, namely precisely weighing carboxyl polyester resin, epoxy resin, a curing accelerator, a leveling agent, a degasifying agent, pigment and filler and a charge regulating auxiliary agent according to parts by weight, dry-mixing 2-6 min in a high-speed mixer at 800-1500 rpm and controlling the discharging temperature to be less than or equal to 40 ℃, putting the dry-mixed materials into a double-screw extruder for melt mixing and extrusion, wherein the screw speed is 200-500 rpm and the material residence time is 30-90 s, and crushing, crushing and sieving the extrudate after cooling to be less than 35 ℃ to obtain base powder without brush polymer modified microbeads and without metal pigment; S4, introducing modified microbeads through low-temperature dry bonding, namely putting the base powder obtained in the step S3 into dry plating bonding equipment, heating the powder to 30-45 ℃, mixing 1-2 min by 600-1500 rpm, adding a dry plating binder to form a capturing layer on the surface of the base powder particles, adding brush-shaped polymer modified microbeads obtained in the step S2 for 2-4 times, controlling the total mixing time of the step to be 3-8 min at each adding interval of 30-60S, enabling the modified microbeads to adhere to the surface or shallow layer of the base powder particles preferentially, cooling to below 30 ℃ in 1-3 min, and sieving for 120-200 meshes, wherein the adding amount of the dry plating binder is 50-100% of the total adding amount of a formula, and the rest of the brush-shaped polymer modified microbeads can be added in the step S5; S5, dry plating metal bonding, namely putting the powder obtained in the step S4 into dry plating bonding equipment, mixing 3-10 min under the conditions of 35-50 ℃ and 500-1200 rpm, adding the metal pigment for 2-3 times at the adding interval of 30-60S, cooling to below 30 ℃ after mixing, and sieving by 120-200 meshes to obtain the microbead modified corrosion-resistant dry plating metal powder coating material.
  8. 8. The preparation method of the microbead modified corrosion-resistant dry-plated metal powder coating material is characterized in that in the step S1, the alcohol/ester mixed solvent is a mixed system of ethanol and ethyl acetate with the volume ratio of 70-90:10-30, the silane coupling agent is one or more selected from 3- (2-bromoisobutyryloxy) propyltrimethoxysilane, 3- (2-bromoisobutyryloxy) propyltriethoxysilane, 3- (2-chloroisobutyryloxy) propyltrimethoxysilane and 3- (2-chloroisobutyryloxy) propyltriethoxysilane, and the addition amount of the silane coupling agent is 1-3 wt% based on the mass of solid glass microbeads.
  9. 9. The method for preparing the microbead modified corrosion-resistant dry-plated metal powder coating material according to claim 7, wherein in the step S2, the surface-initiated controllable free radical polymerization is a photoinduced electron transfer reversible addition-fragmentation chain transfer polymerization reaction, a 405-470 nm light source is adopted, the illuminance is 5-30 mW/cm 2 , the chain transfer agent is one or more of a trithiocarbonate chain transfer agent and a dithiobenzoate chain transfer agent, the addition amount of the chain transfer agent is 0.2-5.0 wt percent based on the total mass of brush layer monomers, the addition amount of the photocatalyst is one or more of eosin Y and rose bengal B, the addition amount of the photocatalyst is 10-2000 ppm percent based on the total mass of brush layer monomers, oxygen is controlled by nitrogen bubbling for 10-30 min percent before polymerization, the reaction temperature of the first reaction stage is 35-45 ℃ and the reaction time is 0.5-2 h, and the second reaction stage is carried out by continuously adding a functional monomer mixture in the range of 0.5-2 h and continuing the reaction for 1-4 h percent.
  10. 10. The method according to claim 7, wherein in the step S3, the temperatures of the zones of the twin-screw extruder are 85-90 ℃, 90-95 ℃, 95-100 ℃, 100-105 ℃ and 105-110 ℃.

Description

Microbead modified corrosion-resistant dry-plated metal powder coating material and preparation method thereof Technical Field The invention relates to the technical field of coating material preparation, in particular to a microbead modified corrosion-resistant dry-plated metal powder coating material and a preparation method thereof. Background The powder coating is widely used for protecting and decorating metal base materials due to no solvent, low VOC, compact coating and high construction efficiency. The dry plating metal powder coating can obtain strong metal texture and flickering effect by bonding the flaky metal pigment and the base powder in a dry way, and is suitable for the scenes of building profiles, household appliances, industrial equipment and the like. However, the system has long-term contradiction between corrosion resistance and appearance stability, namely, the conductivity and flaky morphology of the metal pigment are easy to change the microstructure of a coating film and cause local electrochemical activation, bubbling, pitting and penetration of corrosive media along an interface are easy to occur under the salt spray condition, and meanwhile, complicated components are easy to generate uneven film thickness under the influence of Faraday cage effect, so that the corrosion risk of edges and groove parts is further amplified. The prior art generally improves corrosion resistance by adding rust-preventive pigments such as phosphate, molybdate and the like, lamellar shielding fillers or modifying inorganic fillers by adopting silane coupling agents. However, in dry plated metal systems, increased amounts of rust inhibitive pigments and fillers tend to impair the metal appearance and result in poor leveling, increased orange peel, and limited inhibition of defective corrosion by scratches/microcracks. The conventional silane coupling layers are mostly small molecular interfaces, and are difficult to resist the debonding of a filler-matrix caused by heat circulation and humid heat aging for a long time after curing, so that an interface permeation channel is formed. On the other hand, the problems of agglomeration, uneven electrification, reduced powdering rate, increased local defects and the like can occur if functional particles are introduced and the surface characteristics are not matched, and the construction stability and durability consistency are affected. Therefore, a technical scheme suitable for a dry-plated metal powder system is needed, and on the premise of maintaining the metal appearance and the spraying stability, the interface densification and penetration channel inhibition are realized, the salt spray resistance and the wet heat resistance are improved, and the corrosion expansion rate at scratch/microcrack positions is reduced, so that the comprehensive durability and the application adaptability of the coating are improved. Disclosure of Invention In order to overcome the defects in the prior art, the invention aims to provide a microbead modified corrosion-resistant dry-plated metal powder coating material and a preparation method thereof. The material comprises carboxyl polyester resin, epoxy resin, a curing accelerator, a leveling agent, a degasifying agent, pigment filler, brush polymer modified microbeads, metallic pigment, a dry plating binder and a charge regulating auxiliary agent. The powder coating material has the advantages of keeping the metal appearance and construction stability, remarkably improving corrosion resistance and durability, along with strong interface bonding of a coating film, few pore channels, effectively inhibiting foaming, pitting and corrosive medium permeation along the interface in a salt spray environment, reducing the corrosion rate along scratch expansion and prolonging service life after the scratch or the microcrack is formed, along with uniform powder charging, high powder coating rate, more uniform film thickness distribution, stable dry plating metal effect and small recycling chromatic aberration fluctuation, and is suitable for protecting and coating the metal base materials with the requirements on the appearance and corrosion resistance. In order to achieve the above purpose, the present invention provides the following technical solutions: 55-65 parts of carboxyl polyester resin, 6-14 parts of epoxy resin, 0.2-0.8 part of curing accelerator, 0.8-1.5 parts of flatting agent, 0.2-0.6 part of degasifying agent, 10-20 parts of pigment filler, 2-8 parts of brush polymer modified microbeads, 3-10 parts of metal pigment, 0.15-0.6 part of dry plating binder and 0.05-0.3 part of charge regulating auxiliary agent; The brush-shaped polymer modified microbeads are composite particles taking solid glass microbeads as cores, the surfaces of the brush-shaped polymer modified microbeads are anchored with surface initiation sites through silanization, and polymer brush layers are grown on the surfaces of the glass microbeads in sit