2000 Hours Salt Spray Chemical Resistant High Gloss Tgic Free Epoxy Aluminium Powder Coating
Powder coating is a multi-step surface finishing process suitable for metal and non-metal substrates. The method includes a preparation, application, and curing stage, and, at a minimum, utilizes a spray gun, spray booth, and curing oven.
Overview of Powder Coat Process and Equipment
In contrast to the liquid coating process, which utilizes a liquid coating suspension, powder coating is a dry finishing process which employs powdered coating material. During the process, the powder is applied to a substrate’s pretreated surface, melted, and then dried and hardened into a protective/decorative coating. There are three stages: surface preparation, coating application, and heat curing.
Before the application of any powder coating material, the surface of the substrate must be cleaned and treated to ensure that the part is free of dust, dirt, and debris. If a surface is not sufficiently prepared, any remaining residues and deposits could affect the adhesion of the powder and the quality of the final finish. A complete preparation treatment is mainly dependent on the material being coated. However, some of the steps that are commonly employed during this stage include cleaning, rinsing, etching, blasting, and drying, and the most widely used equipment include wash stations, blast rooms, and dry-off ovens.
Oil, grease, solvent, and residue can be removed from a part’s surface with weak alkali and neutral detergents in dip tanks or with wash stations. Wash stations are capable of spraying parts with hot water, steam, detergent, and other pretreatment solutions to clean, chemically prepare, and rinse the surface before coating.
If the component design requires certain sections to remain uncoated, masking products (e.g., masking dots) are applied to the substrate prior to the application stage. These aforementioned products are available in a variety of standard and custom shapes and forms. However, generally, they are constructed of paper or plastic film coated with a pressure sensitive adhesive, which allows them to adhere to the substrate and protect the covered area from coming into contact with powder material during powder coating operations.
As discussed in the next section, there are two types of powder coating materials that can be applied. The type of coating material being used in a coating application, in part, determines the application method. There are two main methods employed by manufacturers and finishing service providers—electrostatic deposition (ESD) and fluidized bed powder coating.
Electrostatic deposition (ESD): For most metal parts, the coating material is applied via electrostatic spray deposition. This application method employs a powder spray booth, powder feeder, electrostatic spray gun, and, depending on the type of gun used, a power unit.
The spray booth serves as a work area for applying powder material onto a part, and can also act as an air filter and powder overspray containment and recovery system. Fluidized powder material is distributed from the feeder unit to the powder coat gun, which is used to both impart an electrical charge onto the powder and apply it to the substrate. There are three types of electrostatic guns commonly used—Corona, Tribo, and Bell. The electrically-charged particles can then adhere to the part’s electrically grounded surface and will remain adhered as long as they maintain some of their charge. Any overspray material can be collected by the recovery and retrieval systems and reused in future coating applications.
Fluidized bed powder coating: Unlike in ESD where the liquid paints materials are electrostatically sprayed and adhered onto a surface, in fluidized bed powder coating, preheated parts are dipped into the powder material within a fluidized bed. There is also an alternative option called electrostatic fluidized bed powder coating, which generates a cloud of electrically charged powder particles above the fluidized bed through which a part is passed to be coated.
The particularities and characteristics of the powder coating process’s curing stage are mainly determined by the method in which the dry powder is applied, as well as the type of powder coating material employed.
Curing ESD coated parts: Parts that are powder coated via ESD must be cured in a powder curing oven. While the cure schedule for a part is mostly dependent on its size, shape, and thickness, generally a curing oven operating between 325 to 450 degrees Fahrenheit will result in cure times that range between ten minutes to over an hour. Accordingly, smaller powder coated parts require less curing time and lower volumes of heated air to cure fully, and larger parts need more. As the ESD coated part reaches the optimum curing temperature within the oven, the powder particles melt and flow together to form a continuous film over the part’s surface.
Curing fluidized bed coated parts: For parts that are coated within a fluidized bed, the parts are heated before the coating application stage in ovens similar to those used to cure ESD coated parts. As the preheated part is immersed in the coating material, the powder particles melt and flow together upon contact with the part’s heated surface. Parts that are coated via electrostatic fluidized bed powder coating can be either preheated before being passed through the powder coating cloud—in which case the powder coating formed would be to those produced by the regular fluidized bed method—or the part can be heated and cured in a curing oven after it has been coated, like with the ESD coating method.
Once the powder coated part is cool enough to handle, the part can be, if necessary, assembled, packaged, and shipped.
It is made of epoxy resin, curing agent, pigment, filler and additives through melting,
extruding, grinding and processing.
Good adhesive force;
Good leveling property;
Excellent physical and mechanical performance;
Excellent resistance to chemicals.
It is applicable to the coating of enclosure of instruments and meters,
and auto parts and particularly casting industry such as pipelines, casting pipe, casting parts; it is also used for steel bar,
steel formwork, and oil-resistance tools in kitchen.
It can be made into common powder with various glosses and colors,
art powder and power paint
with metal effect according to customers’ requirements.
|Residue on sieve 125 μm
||0 or based on negotiation
|Color and appearance of paint film
The paint film should be smooth but slight orange
peel is allowed and the color should meet
the color difference
||High gloss ≥86, semi gloss 21-85, matt ≤20
|Adhesive force (1×1 mm) Grade 6×6
|Impact resistance kg.cm
|Acid resistance (HCI 3%)240 h
||The film has no change.
|Alkali resistance (NaOH 5%) 168 h
||Slight change is allowed but it shall be recovered within 2h
|Salt spray resistance 400 h
||≤ Grade 1
|Damp-heat resistance 500 h
||≤ Grade 1
|Film thickness μm
The corresponding treatment method should be used based on the substrates,
such as phosphating, chromizing, shot blasting or blast cleaning
1. The surface roughness should be 30 ~75 μm if reaching Grade Sa2.5 by shot blasting
or blast cleaning.
2. Phosphating: degreasing- derusting- neutralizing- surface control- phosphating- passivating
Appearance of phosphating film: The phosphating film should be crystallized densely
continuously and evenly.
3. Chromizing: degreasing- rinsing- immersion cleaning- deoxidating- rinsing- chromizing
|Epoxy powder coating
||Epoxy polyester powder coating
||Polyester TGIC Powder Coating
Polyester TGICfree Powder coating
||Good chemical resistance
||Excellent UV resistance
|Excellent chemical resistance
||Good mechanical performance
|High mechanical performance
||Excellent overbake stability
|Recommended for interior
||Recommended for interior
||Recommended for exterior
① We use the better resin
• Much higher first pass rate
• Better hardness
• Better abrasion resistance,flexibility
• Better chemical resistance
② We use better pigment
• Better hiding
• More mileage
• Stronger UV Stability and weatherability
• Lower necessary film thickness
③ We use a higher resin content
• More excellent quality
• Higher first pass transfer efficiency
④ We offer a higher stability between batches
• Higher First pass Rate on the line
• Much higher satisfaction
• Less customer claims
|Grid Test 1mm
|Heat Resistance 1000 hours
|Salt Spray 1000 hours
||FOB, CIF, CRF, CNF
||T/T, L/C, West Union, PayPal etc.
||3-7 days after payment
||Size: 39*26*43 (unit:cm) Weight: N.W. 25kg G.W. 26kg
||By sea, by air, by courier