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Test Xerographic Carrier Coating

IP.com Disclosure Number: IPCOM000040829D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Crossan, SC: AUTHOR [+2]

Abstract

The tendency of polymer carrier coatings to break away from the underlying steel shot is tested by subjecting the carrier beads to agitation in a Faraday cage.

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Test Xerographic Carrier Coating

The tendency of polymer carrier coatings to break away from the underlying steel shot is tested by subjecting the carrier beads to agitation in a Faraday cage.

A xerographic carrier can consist of 150 microns to 400 microns diameter steel shot onto which a 3 to 5-micron thick coating of mixed fluoropolymer and binding resin is applied. It is desirable that the life of the carrier be as long as possible. The primary carrier failure mode is permanent adhesion of toner to the surface of the carrier (FOT), which then interferes with the triboelectric charging of the toner carrier mix. The carrier, when new, resists adhesion of toner due to the low surface energy of the fluoropolymer component of the carrier coating. The normal mode of long-term failure is for the fluoropolymer at the coating surface to be depleted, and for the surface energy of the coating to increase, allowing toner to adhere. This process is predictable, and results in the carrier being replaced at regular intervals.

A second failure mechanism occurs when the coating cracks, under repeated stress, and patches of coating are chipped off, exposing steel having only a thin residual coating onto which toner can adhere. This type of failure is less predictable.

A means of comparing the resistance of carrier coating to cracking, under repeated impacts and long-term stress, is provided by a Faraday cage-type blowoff device, of the type normally used to remove toner from the carrier while measuring the toner's triboelectric charge. Toned carrier is placed in an aluminum cylinder with screens at both ends. The cylinder is shaken, while air is blown alternately into one end and then the other, to remove the toner. The level of stress is determined...