Powder coatings characteristics

To investigate the effect of different epoxidized fatty acids on the final powder coating characteristics, model compounds have been studied. If desirable, lower cross-... 

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. 

Staniforth JN, Reeves LA, Page T. Electrostatic powder coating of tablets I design and characteristics of a continuous coater prototype. Proceedings of the 13th Annual Meeting Exposition of AAPS, San Francisco, 1998. 

Solder powders coated with a thin layer of Parylene exhibit a high degree of resistance to oxidation and to reaction with the flux contained in the solder paste without substantially interfering with the reflow characteristics of the solder. The powders are used as such or as solder paste. The preferred Parylene type is Parylene E, made from 4-ethyl[2.2]paracylophane since it melts below the melting point of the solder, i.e., about 180°C." The formulation of a typical solder pastes are shown in Table 2.4. 

Jagannathan, V. (1992). The influence of coating characteristics on the powdering and corrosion resistance of galvannealed coated steel sheet. Galvatech 92, Verlag Stahleisen, Diisseldorf, Germany, pp. 127-131. 

Methods for evaluating the performance of powder coatings are the same as those used for conventional coatings. Test methods for coating powders include particle size distribution, powder free flow, sintering, fluidization characteristics, and others. They have been reviewed in detail and reported in the literature (120,121). In addition, the American Society for Testing and Materials has issued a comprehensive standard that covers the most important test methods for the evaluation and characterization of powder coatings (122). 

These characteristics make the planetary gear extruders well suited for processing heat-sensitive materials such as rigid and flexible PVC. They are also used to process blends (eg, PVC and ABS), plastic foams, powder coatings, epoxy, polyester, acrylic, polyurethane, chlorinated polyethylene, etc. 

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