Electrostatic fuser rolls and belts

Abstract

Heat rolls and fuser belts utilized in the fusing step of the electrophotographic process are disclosed. These belts and rollers eliminate toner offset while still maintaining excellent release characteristics of the printed page from the fuser. The heat rolls comprise a core member having coated thereon a plurality of concentric layers, wherein at least one of said layers (preferably the top layer) does not contain electrically conductive materials and wherein the roll exhibits electrical breakdown at about 250 volts or less. The fuser belts comprise a heat resistant resin substrate (such as a polyimide belt) carrying thereon a plurality of layers coating the outer surface of said belt, wherein at least one of said layers (preferably the top layer) does not contain electrically conductive materials and wherein the belt exhibits electrical breakdown at about 250 volts or less.

What is claimed is:  
     
         1 . A heat roll fixing device for use in electrophotography comprising a core member having coated thereon a plurality of concentric layers, wherein at least one of said layers does not contain electrically conductive materials and wherein the roll exhibits electrical breakdown at about 250 volts or less.  
     
     
         2 . The heat roll according to    claim 1    wherein the layers comprise a primer layer on said core, an intermediate layer on said primer layer, and a topcoat layer on said intermediate layer.  
     
     
         3 . A heat roll according to    claim 2    wherein the topcoat layer does not contain electrically conductive materials.  
     
     
         4 . A heat roll according to    claim 3    wherein the primer and intermediate layers comprise a fluoropolymer containing electrically conductive materials.  
     
     
         5 . A heat roll according to    claim 4    wherein the electrically conductive material is selected from the group consisting of carbon black, ionic conductive additives, and mixtures thereof.  
     
     
         6 . A heat roll according to    claim 5    wherein the electrically conductive materials is present at from about 1% to about 10% based on the weight of the fluoropolymer.  
     
     
         7 . A heat roll according to    claim 5    wherein the primer layer has a thickness of from about 1 to about 13 μm, the intermediate layer has a thickness of from about 15 to about 30 μm, and the topcoat layer has a thickness of from about 1 to about 7 μm.  
     
     
         8 . A heat roll according to    claim 7    wherein the primer layer has a thickness of from about 2 to about 5 μm, the intermediate layer has a thickness of from about 18 to about 22 μm, and the topcoat layer has a thickness of from about 2 to about 3 μm.  
     
     
         9 . A heat roll according to    claim 8    wherein the core member is made from aluminum.  
     
     
         10 . A belt for use in an electrophotographic heat fixing process, comprising a heat resistant resin substrate in the form of a continuous belt carrying thereon a plurality of layers sequentially coating the outer surface of said belt, wherein at least one of said layers does not contain electrically conductive materials, and wherein the belt exhibits electrical breakdown at about 250 volts or less.  
     
     
         11 . The fuser belt according to    claim 10    wherein the belt is made from polyimide resin.  
     
     
         12 . The fuser belt according to    claim 11    wherein the layers carried by said belt comprise a primer layer directly covering said belt, an intermediate layer directly covering said primer layer, and a top layer directly covering said intermediate layer.  
     
     
         13 . The fuser belt according to    claim 12    where in the topcoat layer does not contain electrically conductive materials.  
     
     
         14 . The fuser belt according to    claim 13    wherein the primer layer and intermediate layer both comprise a fluoropolymer and electrically conductive materials.  
     
     
         15 . The fuser belt according to    claim 14    wherein the electrically conductive materials are selected from the group consisting of carbon black, ionic conductive additives, and mixtures thereof.  
     
     
         16 . The fuser belt according to    claim 15    wherein the electrically conductive additives are present at from about 5% to about 30% based on the weight of the fluoropolymer in the primer layer and at from about 1% to about 5% based on the weight of the fluoropolymer in the intermediate layer.  
     
     
         17 . The fuser belt according to    claim 13    wherein the polyimide belt contains from about 15% to about 30% of a thermally conductive material.  
     
     
         18 . A fuser belt according to    claim 17    wherein the thermally conductive material is boron nitride.  
     
     
         19 . A fuser belt according to    claim 15    wherein the thickness of the polyimide belt is from about 30 to about 60 μm, the thickness of the primer layer is from about 1 to about 10 μm, the thickness of the intermediate layer is from about 5 to about 20 μm, and the thickness of the top layer is from about 2 to about 5 μm.  
     
     
         20 . The fuser belt according to    claim 19    wherein the thickness of the polyimide belt is from about 45 to about 55 μm. The thickness of the primer layer is from about 2 to about 5 μm, the thickness of the intermediate layer is from about 8 to about 12 μm, and the thickness of the top layer is from about 2 to about 3 μm.