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CN-122011906-A - Vehicle-mounted central control large-screen magnesium alloy base composite coating and preparation method and application thereof

CN122011906ACN 122011906 ACN122011906 ACN 122011906ACN-122011906-A

Abstract

The invention belongs to the technical field of magnesium alloy substrate coating materials, and discloses a vehicle-mounted medium-control large-screen magnesium alloy base composite coating, a preparation method and application thereof, wherein the composite coating is formed by constructing a double-layer system of a base coat and a top coat, the base coat is prepared by taking phosphate modified saturated polyester as a main film forming material, matching with aluminum zinc phosphate hydrate and mica powder functional filler, and adopting pyrazole blocked isocyanate curing agent to realize high crosslinking; the surface coating is cured by the cooperation of high molecular weight thermosetting acrylic resin and methyl etherified high imino melamine cross-linking agent, and aluminum paste, mica powder and the like are compounded to realize excellent decoration and protection, and the composite coating has the characteristics of excellent boiling resistance, salt fog resistance, wear resistance, scratch resistance and the like.

Inventors

  • YIN JUN
  • GAO YUANQING
  • YI HONGXIA
  • CAI YONGCHENG
  • YAN CHENG
  • WANG ZIHAO
  • DAI WEIJUN
  • XU AO
  • JIN ZHENGBEI

Assignees

  • 芜湖春风新材料有限公司

Dates

Publication Date
20260512
Application Date
20260306

Claims (9)

  1. 1. The vehicle-mounted medium-control large-screen magnesium alloy base composite coating is characterized by comprising an undercoat coating and a topcoat coating, wherein the undercoat coating is prepared from the following raw materials in percentage by mass: Solvent type resin-free carbon black slurry 10-20%; 45-65% of phosphate modified saturated polyester; 3-9% of pyrazole blocked isocyanate curing agent; 0.5-3% of cyclized silanol adhesion promoter; 0.1-0.5% of acrylate leveling agent; 1-4% of hydrophobic silica matting powder; 5-10% of aluminum zinc phosphate hydrate; 5-10% of mica powder; 5-10% of a diluent; the top coating paint is prepared from the following raw materials in percentage by mass: Solvent type resin-free carbon black slurry 10-20%; 1.00-3.00% of aluminum paste; 40.00-50.00% of thermosetting acrylic resin; Methyl etherified high imino melamine cross-linking agent 10.00-20.00%; 0.1-0.5% of acrylate leveling agent; Pyrazole blocked isocyanate curing agent 0-6%; 3-5% of hydrophobic silica matting powder; 5-8% of mica powder; 5-11% of a diluent.
  2. 2. The vehicle-mounted medium-control large-screen magnesium alloy base composite coating according to claim 1, wherein the solvent type resin-free carbon black slurry is prepared from the following raw materials in percentage by mass: 40-60% of propylene glycol methyl ether acetate; 10-20% of butyl acetate; 15-25% of polyurethane dispersant; 10-20% of carbon black.
  3. 3. The vehicle-mounted medium-control large-screen magnesium alloy base composite coating according to claim 1, wherein the diluent is prepared from the following raw materials in percentage by mass: 10.00-30.00% of propylene glycol methyl ether acetate; butyl acetate 10.00-30.00%; 20.00-40.00% of cyclohexanone; 20.00-40.00% of methyl isobutyl ketone.
  4. 4. The composite coating for the vehicle-mounted medium-control large-screen magnesium alloy base, according to claim 1, is characterized in that the preparation method of the phosphate modified saturated polyester comprises the following steps: And (3) putting dicarboxylic acid, phosphorus-containing monomers and dihydric alcohol components into a reaction vessel, introducing nitrogen for protection, adding an esterification catalyst, stirring and heating to 180-200 ℃ under normal pressure for esterification reaction until the acid value is reduced to 10-15 mg KOH/g, then heating to 230-245 ℃, gradually reducing the pressure until the vacuum degree is less than or equal to 500Pa, and performing polycondensation reaction until the acid value is 2-5 mg KOH/g to obtain the phosphate modified saturated polyester.
  5. 5. The vehicle-mounted medium-control large-screen magnesium alloy base composite coating according to claim 4 is characterized in that dicarboxylic acid is one or more of terephthalic acid or adipic acid, dihydric alcohol is one or more of 1, 4-butanediol, neopentyl glycol or 1, 6-hexanediol, phosphorus-containing monomer is one or more of bis (2-hydroxyethyl) phosphate or bis (2-hydroxyethyl) phenylphosphonate, and the molar ratio of dicarboxylic acid to phosphorus-containing monomer to dihydric alcohol is 20:1-3:22-26.
  6. 6. The vehicle-mounted medium-control large-screen magnesium alloy base composite coating according to claim 4 or 5, wherein the esterification catalyst is one or more of tetrabutyl titanate or isopropyl titanate, and the dosage is 0.01-0.1wt% of the total mass of dicarboxylic acid and dihydric alcohol.
  7. 7. A method for preparing the vehicle-mounted medium-control large-screen magnesium alloy base composite coating as claimed in any one of claims 1 to 6, which comprises the following steps: 1) Mixing all raw materials of the base coat paint to obtain the base coat paint; 2) And mixing the raw materials of the top coating to obtain the top coating.
  8. 8. Use of the composite coating for a vehicle-mounted large-screen magnesium alloy base according to claim 1 for preparing a vehicle-mounted large-screen magnesium alloy base coating.
  9. 9. The preparation method of the vehicle-mounted central control large-screen magnesium alloy base coating is characterized by comprising the following steps of: a. sequentially degreasing, pickling, alkali washing and micro-arc oxidation treatment are carried out on the vehicle-mounted central control large screen magnesium alloy base to obtain a surface treated workpiece; b. Spraying the bottom coating in the vehicle-mounted large-screen magnesium alloy base composite coating according to claim 1 to the surface-treated workpiece, and then spraying the top coating in the vehicle-mounted large-screen magnesium alloy base composite coating according to claim 1 to obtain the spray-treated workpiece; c. and (3) leveling the workpiece after the spraying treatment, and then baking.

Description

Vehicle-mounted central control large-screen magnesium alloy base composite coating and preparation method and application thereof Technical Field The invention relates to the technical field of magnesium alloy substrate coating materials, in particular to a vehicle-mounted medium-control large-screen magnesium alloy base composite coating, and a preparation method and application thereof. Background The magnesium alloy is a light alloy material which takes magnesium as a matrix and is added with elements such as aluminum, zinc, manganese, rare earth and the like, and is represented by AZ91D magnesium alloy, has excellent performances in structural strength, specific rigidity, vibration damping property, thermal conductivity, electromagnetic shielding property and the like, and is widely applied to the fields of electronic product shells, automobile light parts and the like, however, the thermodynamic standard electrode potential of the magnesium alloy is lower than-2.36V, the activity is high, corrosion is extremely easy to occur under humid environment, salt fog condition and the like, and the reliable use of the magnesium alloy under the severe environments such as humidity, salt fog and the like is severely restricted. Therefore, in order to exert the light weight advantage of magnesium alloy and ensure the long-term service stability, proper protection treatment is required to be carried out on the surface of the magnesium alloy, common processes comprise chemical conversion film, anodic oxidation, electroplating, organic coating application or metal/ceramic composite coating application, and the like, in the prior art, one typical method is to carry out chemical phosphate conversion treatment firstly and then apply the organic coating on the magnesium alloy, the invention patent with the application number of CN200610019324.5 discloses a magnesium alloy phosphate surface modification treatment method, a phosphate chemical conversion film layer is formed on the surface of the magnesium alloy through degreasing, acid washing, alkali washing, chemical film formation, sealing and other steps, the corrosion resistance and the coating adhesion of the magnesium alloy are effectively improved, and although the technical scheme is still insufficient in terms of corrosion protection, on one hand, the phosphate conversion film is generally thinner, the structure is fragile, and is difficult to simultaneously meet various requirements of scratch resistance, friction resistance, salt spray resistance, decoration resistance and the like, on the other hand, and the interface binding force, the coating compactness and long-term stability between the magnesium alloy and a magnesium alloy substrate are difficult to meet the requirements of high-durability application, especially easy to fall off under the condition of water when the magnesium alloy substrate is covered by the conventional organic coating. Thus, there is a need for a new composite coating system for magnesium alloys that combines salt spray resistance, water boiling resistance, and abrasion and scratch resistance to meet the high demands of vehicle applications for long term weatherability and durability. Disclosure of Invention The invention aims to provide a vehicle-mounted medium-control large-screen magnesium alloy base composite coating and a preparation method thereof, and the water boiling resistance, the wear resistance and the service stability of a final coating are improved by constructing a coating system suitable for a magnesium alloy substrate. The invention also aims to provide an application of the vehicle-mounted medium-control large-screen magnesium alloy base composite coating. The invention provides a vehicle-mounted medium-control large-screen magnesium alloy base composite coating, which comprises an undercoat coating and a topcoat coating, wherein the undercoat coating is prepared from the following raw materials in percentage by mass: Solvent type resin-free carbon black slurry 10-20%; 45-65% of phosphate modified saturated polyester; 3-9% of pyrazole blocked isocyanate curing agent; 0.5-3% of cyclized silanol adhesion promoter; 0.1-0.5% of acrylate leveling agent; 1-4% of hydrophobic silica matting powder; 5-10% of aluminum zinc phosphate hydrate; 5-10% of mica powder; 5-10% of a diluent; the top coating paint is prepared from the following raw materials in percentage by mass: Solvent type resin-free carbon black slurry 10-20%; 1.00-3.00% of aluminum paste; 40.00-50.00% of thermosetting acrylic resin; Methyl etherified high imino melamine cross-linking agent 10.00-20.00%; 0.1-0.5% of acrylate leveling agent; Pyrazole blocked isocyanate curing agent 0-6%; 3-5% of hydrophobic silica matting powder; 5-8% of mica powder; 5-11% of a diluent. The solvent type resin-free carbon black slurry is prepared from the following raw materials in percentage by mass: 40-60% of propylene glycol methyl ether acetate; 10-20% of butyl acetate; 15-25