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Water Injection in Toner Milling Device

IP.com Disclosure Number: IPCOM000048524D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Johnston, MS: AUTHOR [+3]

Abstract

The throughput, and the small particle size output, of a jet mill used to mill xerographic toner pellets, is increased by the injection of a controlled amount of water into the jet mill.

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Water Injection in Toner Milling Device

The throughput, and the small particle size output, of a jet mill used to mill xerographic toner pellets, is increased by the injection of a controlled amount of water into the jet mill.

Conventional toner manufacturing techniques provide for the production of relatively large pellets of a homogeneous material from which toner powder is to be formed. A jet mill receives these pellets. Compressed air (typically 100 pounds per square inch) and/or a mechanical rotor provides the kinetic energy to cause collisions between pellets which eventually result in a breaking up of the pellets into powder. The powder then exits the jet mill in the resulting air stream.

As the production rate of the jet mill is increased, the additional energy input will cause the temperature of the exhaust airstream, as well as within the jet mill, to increase to a level Incompatible with the fusing temperature of the toner.

Through the injection of water into the jet mill at a controlled rate, and in the inlet airstream, the water's heat of vaporization can be used to reduce these operating temperatures. This reduction in operating temperature can also be used to control the "fines" content of the resulting toner powder.

Analysis of a thermodynamic model of the jet mill process determines the maximum mass flow of water that can be tolerated, i.e., the adiabatic operating point where all of the water is evaporated into the air within the jet mill.

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