Tribocharge

Materials that have the abiUty to dissipate a charged formed, by any means including tribocharging and induction, on the material are referred to as static dissipative. There is a correlation between static dissipation and surface resistance. EIA-541 currently defines the static dissipative range as 10 to 10 ... 

The usual prescription for controlling triboelectrification in pneumatic transport is to limit the flow rate, but this solution conflicts with the tendency to increase plant production levels. One alternate proposal for the control of tribocharging is to exploit the so-called dense-phase transport mode (G. Butters, 1985) however, there seems to be some dispute about the efficacy ofthis scheme (Konrad, 1986). 

Kim, J.-K., Cho, H.-C., Kim, S.-C. Chun, H.-S. 2000. Electrostatic beneficiation of fly ash using an ejector-tribocharger. Journal of Environmental Science and Health, Part A Toxic/Hazardous Substances and Environmental Engineering, 35, 357-377. 

A known field ie applied, and the tribocharged powder is attracted ortto the... 

Another model that describes the charge transfer process between toner and carrier particles invokes ion transfer . In this model the tribocharging process involves the transfer of ionic species, not just electrons [5b, 6]. The transferred ions are derived from charge control additives which are present as either ionomers or molecular salts in the polymer binder. For ion transfer to occur, dissociated and mobile ions must be present on the particle surface. Initially, each surface contains ions of both polarities, but after repeated contacts the two surfaces become equally but oppositely charged [6a]. The polarity and magnitude of charge transfer can be predicted for certain systems, based on the structure and composition of the ionic... 

In this entry, we review basic charging concepts, corona charging, internal charging, tribocharging, and electrostatic fluidized beds. Along with these methods, some of the properties of powders needed for their application are also discussed. 

Discs use large conical-type deflectors usually mounted in the vertical downward position so that powder is deflected in a horizontal position in a 360°radius. An omega (Q) loop conveyor system normally surrounds the powder disc that is usually mounted on an oscillator or reciprocator for vertical up-and-down motion. The powder can be charged by a corona edge or by tribocharging guns. Typical applications for the powder disc are vertical extrusions or wire goods. 

Rehman, W.R. Lader, H.J. Messerly, J.W. Unipolarity Powder Coating Systems Including Improved Tribocharging and Corona Guns. US Patent 6,645,300, November 11, 2003. 

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