Moisture stable biasable transfer members

Abstract

Abstract The invention provides rolls, belts and other biasable members having at least one layer or coating of an elastomeric resilient polyurethane formed by reacting (a) a polyisocyanate prepolymer comprising the reaction product of a saturated aliphatic polyisocyanate, a saturated cycloaliphatic polyisocyanate, or an aromatic polyisocyanate and a polyol free of aliphatic unsaturation, preferably a polyalkylene glycol in which the alkylene group contains 2 to 8 carbon atoms, and (b), a hardening mixture comprising a polyol of (a) or a diamine free of aliphatic unsaturation, or a mixture thereof and, as a conductivity control agent, from 0.001 to 5.0 weight percent, based on the total weight of (b), of a complex of ethylene glycol or an oligoethylene glycol selected from the group consisting of di-, tri- and tetraethylene glycol with an ionizable metal halide salt selected from the group consisting of stannic tetrafluoride, stannic tetrachloride, stannic tetrabromide and stannic tetraiodide. The resistivity of the elastomeric resilient polyurethane coating on the biasable member is controlled or adjusted to within a desired level of resistivity due to the inclusion of the conductivity control agent in the polyurethane elastomer. Additionally, the inclusion of the conductivity control agent in the polyurethane elastomer reduces the sensitivity or the resistivity of the polyurethane coating on the biasable member to changes in relative humidity. Further, since the conductivity control agent is copolymerized with the polyisocyanate prepolymers and the polyols and/or polyamines which comprise the hardening mixtures used to make the elastomeric polyurethane coatings of the biasable members of the invention, the conductivity control agent is bonded covalently to the polyurethane elastomer matrix or network, i.e., to the backbone, crosslinking or branched portion of the polyurethane elastomer where it forms a permanently fixed part of the polymer and will not migrate therefrom resulting in a continuous change in the resistivity of the polyurethane coating over time and possible adverse affects on materials that may come into contact with the migrating agent. The utility of such biasable members is in the transfer of toner images from an electrostatographic element comprising a conductive support surface, such as a photoconductive support surface or a photoconductor, to a final support sheet where the member, for example, a bias transfer roll, electrically cooperates with the conductive support surface to establish a directional force field therebetween.

Inventors

• 👤 John C. Wilson
• 👤 William B. Vreeland

Bibliographic Details