SILICONE VAPOR FILTER
Original Publication Date: 1990-Jun-30
Included in the Prior Art Database: 2004-Apr-05
Xerox Disclosure Journal
The presence of silicone oil vapor in the atmosphere where some types of business equipment are used has been linked to operational problems and is consequently unwanted. For example, it is known that silicone oil vapor can deposit as an insulating film to contaminate electrical contacts leading initially to intermittent failure and finally a permanent open circuit. The major offenders appear to be low molecular weight linear and cylic siloxanes and linear silanols which are decomposition products from silicone rubber pads used in fuser applications, for example, in electrostatographic copiers and printers with and without additional silicone oil. These vapors may be removed from an air stream with a filter that uses a combination of sorption, oligomerization and entrapment. The sorption mechanism, either physical or chemical, can be achieved on a high sorption surface such as fumed silica about 0.01 microns in diameter to react with the silanol groups. Such a high sorption surface energy filter may be utilized by being impregnated in macropores of activated carbon from 0.5 to 2 microns in diameter or Kieselguhr or activated alumina. Alternatively, it may be present in a siloxane soluble coating on an open celled reticulated foam or pelletized on an open fiber network such as fiberglass. Oligomerization leading to higher molecular weight species via condensation etc., will provide moieties with greatly reduced vapor pressure. This may take the form of a cataylst with or without additional crosslinker such as a tin soap such as dibutyltin diacetate and high molecular weight of ethoxy terminated polydimethyl siloxane impregnated on a carrier, available as a wall coating or coated on open cell reticulated foam. In the entrapment mechanism, the harmful vapors react and/or are trapped in pores of activated carbon or other suitable reactive material. Alternatively, the activated carbon may be doped with ethyoxy terminated polydimetyl siloxane.