Developer rolls having a tuned resistivity method for making
View Patent ↗A method for making a developer roll by molding a metal shaft with a conductive or semi-conductive soft rubber forming a rubber core and a coating deposited on the soft rubber core wherein the coating has a conductive agent. The outer surface of the soft rubber core is modified to form an —OH rich surface layer before the coating is deposited onto the outer surface of the rubber core to chemically bond therein.
1. A method for making a developer roll having a tuned resistivity, comprising:
molding a metal shaft with a conductive or semi-conductive soft rubber to form a rubber core;
modifying an outside surface of the rubber core to form an —OH rich surface layer;
coating the modified rubber core with a polyurethane prepolymer and a conductive additive; and
adhering the coating to the outside surface of the rubber core by chemically bonding an isocyanate portion of the polyurethane prepolymer with the —OH rich surface layer.
2. The method of claim 1 , wherein chemically bonding the isocyanate portion of the polyurethane prepolymer with the —OH rich surface layer includes chemically bonding a caprolactone-H 12 MDI urethane with the —OH rich surface layer.
3. The method of claim 2 , wherein coating the modified rubber core with the conductive additive includes coating the modified rubber core with cesium hexafluoroacetylacetonate.
4. The method of claim 2 , wherein chemically bonding the caprolactone-H 12 MDI urethane with the —OH rich surface layer includes chemically bonding a mixture of caprolactone-H 12 MDI urethane and caprolactone-TDI urethane with the —OH rich surface layer.
5. The method of claim 1 , wherein coating the modified rubber core with the conductive additive includes coating the modified rubber core with one or more ionic additives, an inherently conductive polymer (ICP) or a combination thereof.
6. The method of claim 5 , wherein coating the modified rubber core with the conductive additive includes coating the modified rubber core with an ionic additive selected from the group consisting of: LiPF 6 , LiAsF 6 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , LiPF 3 (C 2 F 5 ), Cs(CF 3 COCH 2 COCF 3 ), KPF 6 , NaPF 6 , CuCl 2 , FeCl 3 , FeCl 2 , Bu 4 NPF 6 , Bu 4 NSO 3 CF 3 , Bu 4 NCl, Bu 4 NBr and a combination thereof.
7. The method of claim 1 , further comprising coating the modified rubber core with a curative additive selected from the group consisting of: polycaprolactone polyols, polyether polyols, polyester polyols, aliphatic-polycarbonate polyols, polybutadiene diol, polydimethylsiloxane polyols, polydimethylsiloxane diamines and a combination thereof.
8. The method of claim 7 , wherein coating the modified rubber core with the curative additive includes coating the modified rubber core with an alkoxylated trimethylolpropane polyether polyol.
9. The method of claim 1 , wherein modifying the outside surface of the rubber core to form an —OH rich surface layer includes applying a UV-ozone treatment to the outside surface of the rubber core.
10. The method of claim 1 , wherein molding the metal shaft with the conductive or semi-conductive soft rubber to form the rubber core includes molding the metal shaft with one or more rubbers selected from the group consisting of: silicone rubber, nitrile rubber, ethylene propylene (EP) copolymers, polybutadiene, styrene-co-butadiene, isoprene rubber, and a blend of one or more of the rubbers.
11. The method of claim 1 , wherein coating the modified rubber core with the polyurethane prepolymer includes coating the modified rubber core with a polyurethane prepolymer having a polyol portion selected from the group consisting of a polyether, a polyester, a polybutadiene system and a combination thereof.
12. The method of claim 1 , wherein coating the modified rubber core with the conductive additive includes coating the modified rubber core with carbon black, carbon fibers, graphite or a combination thereof.