BIAS TRANSFER ROLLS HAVING CONTROLLED RESISTIVITY
Original Publication Date: 1978-Feb-28
Included in the Prior Art Database: 2004-Mar-31
Xerox Disclosure Journal
Rolls, belts and other biasable members made of polyurethane are described in United States Patent No. 3,959,574. The resistivity of the polyurethane coating on biasable members is controlled by additives incorporated in the polyurethane.
XEROX DISCLOSURE JOURNAL
BIAS TRANSFER ROLLS HAVING Proposed Classification
CONTROLLED RESISTIVITY U.S. Cl. 428/425
Donald A. Seanor mt. Cl. B32b 27/40
Rolls, belts and other biasable members made of polyurethane
are described in United States Patent No. 3,959,574. The
resistivity of the polyurethane coating on biasable members is
controlled by additives incorporated in the polyurethane.
The construction of typical biasable transfer rolls is well
known in the art and generally such rolls comprise a conduc-
tive metal core, a soft elastomeric substrate and optio.pally
an overcoating having a resistivity greater than 10 ohm
centimeter. In accordance with this disclosure the soft
elastomeric substrate may be soft silicone rubbers, soft
fluoroelastomer materials, soft organic rubbers and the like.
A preferred range of hardness for the soft elastomers is
between about 40 Shore 00 to about 40 Shore A arid preferably
from about 15 to about 25 durometers.
Preferred transfer rolls are those in which the potential
applied to the core builds up at the surface under operating
conditions. To obtain this build up of potential, the bulk
substrate resistivity should be such that electrical relaxa-
tion occurs within the time that a segment of the surface is
within the nip. This necessitates close control of the roll
resistivity, and roll resistivity control can be achieved by
using additives in the soft elastomeric material.
Additives which are incorporated in the soft elastomeric
substrates as impur...