Powder coatings material

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 coatings as a class are superior to Hquid coatings in abiHty to coat sharp edges and isolate the substrate from contact with corrosive environments. PVC coatings are softer and more flexible than any of the other powder coating materials. Primers used for PVC plastisols have been found generally suitable for powder coatings as weH (5). 

To be suitable for radiation-curable powder coatings, materials must contain unsaturated double bonds. They may contain acrylic or methacrylic unsaturations, but nonacrylate systems can also be used.32 The latter are based on the same chemistry... 

Figure 8.17 Powder coatings made by different processes. (Courtesy DuPont Company.) Table 8.3. ECTFE Powder Coating Materials...

PHA copolymers can be converted into various forms and products, such as films, sheets, fibers, nonwovens, molded articles, pulps, powders, coating materials, laminates, and composites, using conventional processing steps such as extrusion and... 

In-mold coatings with either liquid or powder coating materials are becoming increasingly popular as primers and finish coats for sheet molding compounds and reaction injection-molded materials. In addition to providing decoration and color, in-mold coatings eliminate surface porosity and provide a hard, durable surface. 

F/u/cf/zecf beef. A container holding powder coating material which is aerated from below so as to form an air-supported expanded cloud of such material through which the preheated object to be coated is immersed and transported. 

The performance of powder coatings during fusion and subsequent cure may be followed in detail by thermal analytical procedures such as differential thermal analysis and differential scanning calorimetry. These techniques offer an opportunity for the study of phase transitions and cure behaviour under closely controlled conditions. Differential scanning calorimetry is a requirement in the British Gas standard for epoxy powder coating materials for the external coatings of steel pipes where it is used as a guide to ascertain optimum cure conditions. 

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