Powder coating electrostatic fluidized

Electrostatic spray powder coating. Electrostatic spray powder coating (95 to 1(X)% TE) is a method for applying finely divided, electrostatically charged plastic particles to products that are at ground potential. A powder-air mixture from a small fluidized bed in the powder reservoir is supplied by a hose to the spray gun, which has a charged electrode in the... 

Almost all PVC powder coatings are appHed by the fluidized-bed coating process. Although some electrostatic spray-grade formulations are available, they are very erratic in their appHcation characteristics. The resistivity of plasticized PVC powders is low compared to other powder coating materials and the appHed powder quickly loses its electrostatic charge. For the same reason, PVC powders show poor appHcation characteristics in an electrostatic fluidized bed and are seldom used in this process. 

Powder coating is a solventless coating system that is not dependent upon a sacrificial medium such as a solvent, but is based on the performance constituents of solid TP or TS plastics. It can be a homogeneous blend of the plastic with fillers and additives in the form of a dry, fine-particle-size compound similar to flour. The three basic methods are the fluidized bed, electrostatic spray, and electrostatic fluidized bed processes (9). 

Powder Coating. Nylon-11 and nylon-12 are used in powder form for anticorrosion coating of metals. Dip coating and electrostatic and flame spraying are used. Dip coating, which involves immersing a preheated article into fluidized nylon powder, is most suitable for automation. 

Coatings can be prepared by hot flocking, in which the heated part is dipped into a fluidized bed of ETFE powder and then is removed to cool. ETFE coatings can also be applied by other powder coating methods (e.g., electrostatically) or by spraying of water- or solvent-based suspensions followed by drying and baking [27],... 

Powder coatings are used in dipping operations via fluidized bed and electrostatic fluidized beds. It is the oldest form of powder application. It was first used in Germany in 1950 and was introduced to North America in 1955 (. ... 

The chief characteristic of electrostatically applied powder polymer is the ability to produce a thin coating. It is the preferred method of producing a coating of 0.001-0.002 in. (0.025-0.050 mm) thickness. It is a continuous process and suited to automated assembly-line production. With a well designed recovery system and fully enclosed spray booth, the process permits full utilization of the powder. The particle size of sprayed powders is smaller than that of powders used in fluidized bed coating. The average particles size is 30-60 microns. 

Coating of substrates (particularly metallic substrates) with particulate plastics is a well-established technology. The fluidized-bed process was developed in 1952. The electrostatic powder coating technique introduced in 1965 has, however, made a substantially greater impact [3.46]. These two processes are discussed in Section 8.3.5. 

In powder coatings the coating material is applied to the workpiece in the form of dry (i.e., solvent-free) thermoplastic or thermosetting powder. The powder particles are heated and melt to form a film. The thermoplastic powders melt and fuse on heating whereas the thermosetting powders also become chemically cross-linked. Two main application processes are used electrostatic spraying and fluidized-bed coating. 

Powder coatings are completely solvent free. They are dry blends, so to speak, of pigments and binders. They are either applied with a fluidized bed or by electrostatic spraying onto the substrate to be coated. The most important binders are epoxides, sometimes alone and sometimes in combination with polyesters. Polyurethanes, polyesters combined with triglycidyl isocyanurates, and acrylates combined with oxazolines are also important. 

Powder coating (95 to 100% TE), developed in the 1950s, is a method for applying finely divided, dry, solid resinous coatings by dipping products in a fluidized bed or by spraying them electrostatically. The... 

In an electrostatic fluidized bed small products such as electrical components can be coated uniformly and quickly. The advantages of flnidized bed powder are uniform and reproducible film thickness on all complex-shaped product surfaces. 

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