Patent Publication Number: US-2015064399-A1

Title: Elastomeric Roll for an Electrophotographic Image Forming Device having a Coating that includes Compressible Hollow Microparticles

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This patent application is related to U.S. patent application Ser. No. ______ (Attorney Docket No. P605), filed ______, 2013, entitled “Elastomeric Roll for an Electrophotographic Image Forming Device having Compressible Hollow Microparticles” and U.S. patent application Ser. No. ______ (Attorney Docket No. P608), filed ______, 2013, entitled “Elastomeric Roll for an Electrophotographic Image Forming Device having Compressible Hollow Microparticles Defining a Surface Texture of the Roll.” 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to rolls used in electrophotographic image forming devices and more particularly to a roll for an electrophotographic image forming device having a coating that includes compressible hollow microparticles. 
     2. Description of the Related Art 
     During the image formation process of an electrophotographic image forming device, toner is transferred from a toner reservoir by various toner carrying members (including rolls) to a media sheet to form a toned image on the media sheet. For example, during a print or copy operation, a charging roll charges the surface of a photoconductive drum (PC drum) to a specified voltage. A laser beam is then directed to the surface of the PC drum and selectively discharges those areas it contacts to form a latent image. A developer roll, which forms a nip with the PC drum, may transfer toner to the PC drum to form a toner image on the PC drum. A toner adder roll may supply toner from the toner reservoir to the developer roll. A metering device such as a doctor blade may meter toner onto the developer roll and apply a desired charge on the toner prior to its transfer to the PC drum. The toner is attracted to the areas of the surface of the PC drum discharged by the laser beam. The toner image on the PC drum is transferred either directly by the PC drum or indirectly by one or more intermediate transfer members to the media sheet. The media sheet having the toner thereon passes through a fuser assembly that applies heat and pressure to fix the toner image to the media sheet. 
     Generally, a large portion of the energy consumed by an electrophotographic image forming device is in the power required to drive the motors and rotating components within the device. Reducing the torque required to drive the various rotating components reduces the overall energy consumption of the device. One way to reduce the required torque is to decrease the mass of the rotating components. Accordingly, rolls for use in an electrophotographic image forming device having decreased mass are desired. In addition, decreased mass also reduces the potential for product damage during general shipping conditions, e.g., dropping the product, vibration during shipping, etc. 
     Further, the force subjected to toner as it transfers between various rolls and components on its way from the toner reservoir to the media sheet may damage the toner at the particle level. For example, the particles may deform, fracture or lose extra particulate additives as a result of the forces applied by the components of the image forming device. This damage may lead to print defects such as toner filming. Toner damage may be reduced by decreasing the amount of force applied to the toner during its transfer. Accordingly, rolls for use in an electrophotographic image forming device that reduce toner working are desired. 
     A cost effective method for manufacturing rolls having decreased mass and/or that reduce toner working while maintaining tight control over the rolls&#39; properties is also desired. 
     SUMMARY 
     A roll for use in an electrophotographic image forming device according to one example embodiment includes an elastomeric core having a coating on an outer surface of the elastomeric core. The coating has hollow microparticles dispersed within the coating. The hollow microparticles are compressive and resiliently recoverable after receiving an applied force. 
     A coating for an outer surface of a roll for use in an electrophotographic image forming device according to one example embodiment includes hollow microparticles dispersed within the coating. The hollow microparticles are compressive and resiliently recoverable after receiving an applied force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present disclosure, and together with the description serve to explain the principles of the present disclosure. 
         FIG. 1  is a cross sectional view of a roll having a core with hollow microparticles for use in an electrophotographic image forming device according to one example embodiment. 
         FIG. 2  is a schematic illustration of a process for making the roll shown in  FIG. 1  according to one example embodiment. 
         FIG. 3  is a cross sectional view of a roll for an electrophotographic image forming device having a coating according to one example embodiment. 
         FIG. 4  is an enlarged view of the roll shown in  FIG. 4  showing hollow microparticles dispersed in a coating of the roll according to one example embodiment. 
         FIGS. 5A-C  show sequential views of the response of the coating shown in  FIG. 4  to a force applied to the roll by a doctor blade. 
         FIG. 6  is a cross sectional view of a roll having hollow microparticles providing a surface topography of the roll for use in an electrophotographic image forming device according to one example embodiment. 
         FIG. 7  is a schematic illustration of a process for making the roll shown in  FIG. 6  according to one example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the accompanying drawings where like numerals represent like elements. The embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure. It is to be understood that other embodiments may be utilized and that process, electrical, and mechanical changes, etc., may be made without departing from the scope of the present disclosure. Examples merely typify possible variations. Portions and features of some embodiments may be included in or substituted for those of others. The following description, therefore, is not to be taken in a limiting sense and the scope of the present disclosure is defined only by the appended claims and their equivalents. 
     Referring now to the drawings, and more particularly to  FIG. 1 , a roll  100  for use in an electrophotographic image forming device, such as, for example a developer roll, is shown in cross section according to one example embodiment. In other embodiments, roll  100  may be another roll used in an electrophotographic image forming device such as, for example, a toner adder roll for supplying toner to a developer roll, a charge roll for charging the surface of a photoconductive drum, a backup or pressure roll for a fuser, etc. Roll  100  includes a roll core  102  mounted (e.g., molded) on a shaft  104 . Shaft  104  may be electrically conductive or non-conductive. Conductive material may include metal such as aluminum, aluminum alloys, stainless steel, iron, nickel, copper, etc. Polymeric materials for shaft  104  may include polyamide, polyetherimide, etc. 
     Core  102  may be made of a thermoplastic or thermoset elastomeric type material. The elastomeric material may substantially recover (e.g., &gt;75%) after an applied stress (e.g., a compression type force). The elastomeric material may be any suitable material that provides the ability for roll  100  to elastically deform at a given nip location in the image forming device while also providing some level of nip pressure. For example, core  102  may include an electrically conductive or semi-conductive soft rubber. The soft rubber may include, for example, silicone rubber, nitrile rubber, ethylene propylene copolymers, polybutadiene, styrene-co-butadiene, isoprene rubber, polyurethane, or a blend or copolymer of any of these rubbers. In one embodiment, core  102  is comprised of a polyurethane elastomer including an isocyanate portion and a polyol portion. The isocyanate portion may include, for example, toluene diisocyanate (TDI), polymeric TDI, diphenylmethane diisocyanate (MDI), polymeric MDI, dicyclohexylmethane diisocyanate (H 12 MDI), polymeric H 12 MDI, isophorone diisocyanate (IPDI), polymeric IPDI, 1,6-hexamethylene diisocyanate (HDI), polymeric HDI, etc. The polyol portion may include, for example, a polyether, polyester, polybutadiene, polydimethylsiloxane, etc. having two or more reactive hydroxyl groups or mixtures thereof. The conductivity of core  102  may be supplied by one or more ionic additives, inherently conductive polymers, carbon black, carbon nanoparticles, carbon fibers, graphite, etc. The ionic additives may include, for example, LiPF 6 , LiAsF 6 , LiClO 4 , LiBF 4 , LiCF 3 SO 3 , 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 ) (abbreviated as CsHFAc), 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 or dimethylethyldodecylammonium ethosulfate. The inherently conductive polymer(s) may include, for example, polyaniline, poly(3-alkylthiophenes), poly(p-phenylenes), or poly(acetylenes). 
     Roll  100  also includes hollow microparticles  106  such as hollow microspheres dispersed within core  102 . Hollow microparticles  106  are compressible under a pressure range of 0.1 to 10 bars and are resiliently recoverable to substantially their original size and shape. In one embodiment, the median size of hollow microparticles  106  is between about 1 μm and about 100 μm including all values and increments therebetween and may be as large as 500 μm. In one embodiment, the size range of hollow microparticles  106  (i.e., the difference between the tenth percentile (10%) particle size and the ninetieth percentile (90%) particle size) does not exceed one and a half times (1.5×) the median particle size. In one embodiment, two or more sets of hollow microparticles  106  are dispersed within core  102 , each set differing by at least one property (e.g., size). Where roll  100  includes more than one set of hollow microparticle sizes, in one embodiment, the size range of each set of hollow microparticles  106  (i.e., the difference between the tenth percentile (10%) particle size and the ninetieth percentile (90%) particle size for that set) does not exceed one and a half times (1.5×) the median particle size of the set. Hollow microparticles  106  may include, for example, Expancel® Microspheres from AkzoNobel N.V., Amsterdam, the Netherlands or Dualite® Microspheres from Henkel Corporation, Dusseldorf, Germany. Hollow microparticles  106  may be pre-expanded or expanded during the formation of core  102  as discussed in greater detail below. 
     Roll  100  may include a coating (not shown) on the outer surface of core  102  as desired. For example, the coating may include an electrically conductive material in order to tune the electrical resistivity of the outer surface of roll  100  with respect to core  102 . For example, the coating may include polyurethane and a conductive additive. The isocyanate portion and the polyol portion of the polyurethane may include any of the materials discussed above with respect to core  102 . Additional curatives such as atmospheric moisture or polyamines may be used in conjunction with or as a replacement for the polyol portion of the polyurethane. In this embodiment, polyamines may include, for example, small molecule or polymer structures such as polyethers having two or more reactive amine groups. Further, the conductive additive may include any of the additives discussed above with respect to core  102 . The coating may also include additional fillers such as, for example, silica to control rheological properties. The coating may be applied by any conventional means known in the art such as, for example, dip or spray coating. 
       FIG. 2  is a schematic illustration of a process  1000  for manufacturing roll  100  according to one example embodiment. At step  1001 , the uncured elastomer of core  102  and hollow microparticles  106  in their unexpanded state are loaded into a mixing vessel  1010 . At step  1002 , the uncured elastomer and microparticles are mixed thoroughly to create a uniform dispersion  1012 . At step  1003 , the dispersed mixture  1012  is injected or otherwise loaded into a mold cavity  1014  in the shape of core  102 . At step  1004 , the mold cavity  1014  is heated in order to cure the elastomer and to permanently expand hollow microparticles  106 . In this embodiment, hollow microparticles  106  include a polymer shell (e.g., a poly(methyl acrylate) (PMA) copolymer) encapsulating a gas (e.g., a hydrocarbon such as isobutane). When heated, the internal pressure from the gas increases and the shell stretches plastically thereby increasing the volume of microparticles  106 . In one embodiment, hollow microparticles  106  are permanently expanded upon heating to a temperature between 80° C. and 175° C. At step  1005 , the molded component is cooled and removed from mold cavity  1014  resulting in core  102 . After the hollow microparticles  106  are cooled, the shell retains its increased size without permitting the gas to leak from or deflate the shell. Care must be taken not to overheat the microparticles during step  1004  so as not to damage the shell which may cause the gas to leak from the shell causing the microparticle to deflate and shrink. After core  102  is removed from mold cavity  1014 , core  102  may then be moved to any desired finishing operations such as, for example, a coating operation. In one alternative, hollow microparticles  106  are preexpanded to their final size prior to mixing with the uncured elastomer such that the heating performed at step  1004  cures the elastomer but does not substantially alter the size of hollow microparticles  106 . In another alternative, at step  1004 , mold cavity  1014  is heated to a temperature sufficient to cure the elastomer but less than a minimum temperature at which hollow microparticles  106  permanently expand. The molded component may then be heated above the minimum temperature at which hollow microparticles  106  permanently expand either before or after the molded component is removed from mold cavity  1014  in order to permanently expand hollow microparticles  106 . 
     Example 1 
     Samples were prepared with hollow microspheres having the trade name Expancel® Microspheres from AkzoNobel N.V. (model number 461DU40) dispersed in silicone rubber. The silicone rubber was cured prior to permanently expanding the hollow microspheres. The samples were heated to permanently expand the hollow microspheres and tested to determine the percentage increase in sample thickness resulting from the expansion of the hollow microspheres as summarized in Table 1 below. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Weight Percentage of hollow 
                 % Increase in 
               
               
                   
                 microspheres in silicone rubber 
                 sample thickness 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                  9.1% (9-15 μm microparticles) 
                 3.80% 
               
               
                   
                 20.1% (9-15 μm microparticles) 
                 11.5% 
               
               
                   
                   
               
            
           
         
       
     
     As seen in Table 1, additional expansion of the samples was achieved upon expanding the hollow microparticles even after the silicone rubber had already been cured. It is believed that if the silicone rubber was not cured prior to heating, the observed sample expansion would be much greater. 
     Roll  100  having core  102  with hollow microparticles  106  dispersed therein has a lower mass in comparison with a roll having a solid core without hollow microparticles  106  given the same geometric dimensions. Foam cores are also known to reduce the mass of a roll in comparison with a roll having a solid core. However, the creation of cells using hollow microparticles  106  presents advantages over known foam creating techniques. For example, current foam processes generally utilize a chemical process or an aeration process to form an elastomeric foam having a cell structure. The chemical process relies on a chemical reaction that produces a gas as a byproduct during the formation of the elastomer. The gas creates the cells in the foam. The aeration process introduces air during the mixing process in order to create cells in the foam. Both of these processes require tight process control in order to keep the cell sizes within a desired distribution. In contrast, the density of the cells in roll  100  can be controlled more easily simply by adjusting the percentage of hollow microparticles  106  in core  102 . Further, the cell sizes can be readily controlled by the selection of the hollow microparticles  106  based on the unexpanded or expanded particle size. The cell sizes may also be controlled by the temperature during particle expansion and the duration of heating. The distribution of the cell sizes is dictated by the particle size distribution of the hollow microparticles  106  which can be tightly controlled. Further, because microparticles  106  deflect under pressure and their original shape is recoverable, the hardness of core  102  may be tuned as desired. Accordingly, the inclusion of hollow microparticles  106  in core  102  permits improved process control of the mass and hardness of core  102 . Specifically, the mass and mechanical properties of core  102  may be controlled by adjusting the pore density of core  102  and the mechanical properties of core  102  may be further controlled by controlling the cell sizes. 
     With reference to  FIG. 3 , a roll  200  for use in an electrophotographic image forming device, such as, for example a developer roll, is shown in cross section according to one example embodiment. Roll  200  includes an elastomeric core  202  mounted on a shaft  204 . Shaft  204  may be electrically conductive or non-conductive and may be composed of the materials discussed above with respect to shaft  104  of roll  100 . Like core  102  discussed above, core  202  may be made of a thermoplastic or thermoset elastomeric type material that substantially recovers after an applied stress. Core  202  may be composed of the materials discussed above with respect to core  102  of roll  100  and may include the conductive additives discussed above. In one embodiment, core  202  includes hollow microparticles such as hollow microparticles  106  discussed above. Alternatively, core  202  may be solid in construction or core  202  may be a foam material having a closed cell structure. 
     Roll  200  includes a coating  206  on the outer surface of core  202 . As discussed above, the coating may include an electrically conductive material in order to tune the electrical resistivity of the outer surface of roll  200  with respect to core  202 . The coating may be composed of the materials discussed above with respect to the optional coating of roll  100  and may include the curatives, fillers and conductive additives discussed above. With reference to  FIG. 4 , coating  206  includes hollow microparticles  208  dispersed therein. Hollow microparticles  208  may have the properties and may be composed of the materials of hollow microparticles  106  discussed above with respect to roll  100 . In one embodiment, hollow microparticles  208  are permanently expanded prior to curing coating  206 , which may be cured by any suitable method such as, for example, heating, UV or IR curing, etc. In another embodiment, hollow microparticles  208  are dispersed in coating  206  in their pre-expanded state and expanded to their final size after coating  206  has been cured. In another embodiment, hollow microparticles  208  are dispersed in coating  206  in their pre-expanded state and coating  206  and hollow microparticles  208  are then heated in order to cure coating  206  and to permanently expand hollow microparticles  208 . In one embodiment, two or more sets of hollow microparticles  208  are dispersed within coating  206 , each set differing by at least one property (e.g., size). Where coating  206  includes more than one set of hollow microparticle sizes, in one embodiment, the size range of each set of hollow microparticles  208  (i.e., the difference between the tenth percentile (10%) particle size and the ninetieth percentile (90%) particle size for that set) does not exceed one and a half times (1.5×) the median particle size of the set. 
     With reference to  FIGS. 3 and 4 , in one embodiment, roll  200  includes a coating support layer  210  positioned between coating  206  and the outer surface of core  202 . Coating support layer  210  may be a primer layer that increases the adhesion between coating  206  and the outer surface of core  202 . Coating support layer  210  may alternatively be a layer of the same material as coating  206  except without hollow microparticles  208  in order to achieve a desired total coating thickness (coating support layer  210 +coating  206 ). In another embodiment, no coating support layer  210  is present and coating  206  having hollow microparticles  208  is applied directly to the outer surface of core  202 . In another embodiment, a layer of the coating material without hollow microparticles  208  may be positioned on top of the coating layer  206  having hollow microparticles  208  such that the hollow microparticles  208  of coating layer  206  translate through the coating layer without hollow microparticles  208  to define the surface topography of roll  200 . In one embodiment, the total coating thickness is between about 1 and 100 μm including all values and increments therebetween. In one embodiment, the thickness of the coating layer without hollow microparticles  208  positioned on top of coating layer  206  is between about 1 and 100 μm including all values and increments therebetween. 
     The surface topography and roughness of roll  200  may be tailored to a desired value based on the thickness of coating  206  and the concentration and size of hollow microparticles  208  included in coating  206 . In general, a larger coating thickness will tend to have a lower surface roughness value. Where roll  200  is a developer roll, the surface topography may be tailored to achieve a desired toner mass flow. In general, a rougher surface will tend to carry more toner (by mass) per area of the surface of roll  200 . In one embodiment, the surface roughness (Ra) of roll  200  is between 0.1 and 5.0 μm including all values and increments therebetween. In one embodiment, the surface roughness (Rz) of roll  200  is between 0.1 and 25 μm including all values and increments therebetween. 
     Example 2 
     Samples were prepared with hollow microspheres having the trade name Expancel® Microspheres from AkzoNobel N.V. (model number 461DU40) dispersed in a silicone coating. The mixture was 20% by weight of the microspheres. The coating samples were cured prior to permanently expanding the hollow microspheres. The samples were then heated to permanently expand the hollow microspheres. The samples were tested to determine the surface roughness before and after expansion of the microspheres according to various methods as summarized in Table 2 below. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
             
            
               
                   
                   
               
               
                   
                 Before Heating 
                 After Heating 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Ra 
                 Rz 
                 Rpc 
                 Ra 
                 Rz 
                 Rpc 
               
               
                 Exposure Type 
                 (μm) 
                 (μm) 
                 (cm −1 ) 
                 (μm) 
                 (μm) 
                 (cm −1 ) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 UV Surface Heating 
                 0.091 
                 0.949 
                 3.750 
                 2.091 
                 17.497 
                 242.500 
               
               
                 (5 second exposure) 
               
               
                 Bulk Heating via Oven 
                 0.096 
                 0.948 
                 4.167 
                 0.458 
                 4.610 
                 217.292 
               
               
                 (125° C. for 1 hour) 
               
               
                   
               
            
           
         
       
     
     It is believed that the UV treatment resulted in a higher temperature than the 125° C. oven and therefore caused greater microsphere expansion. Accordingly, it can be observed from Table 2 that the surface roughness of a coating can be tailored by the inclusion of hollow microparticles. 
     As discussed above, hollow microparticles  208  are compressible under pressure and resiliently recoverable to substantially their original shape after deformation.  FIGS. 5A-C  show an example of this dynamic response. In  FIG. 5A , a doctor blade  212  is shown engaged with the outer surface of roll  200  along coating  206 . As roll  200  rotates (to the right or clockwise as viewed in  FIGS. 5A-C ), the generally stationary doctor blade  212  passes along the outer circumference of roll  200  and applies a force to the outer surface of roll  200  across the axial length of roll  200  in order to regulate the amount of toner carried by roll  200 . As roll  200  rotates further, as shown in  FIG. 5B , the force of doctor blade  212  causes hollow microparticles  208  to deflect as doctor blade  212  passes. As roll  200  rotates further, as shown in  FIG. 5C , the hollow microparticles  208  deflected by doctor blade  212  recover to substantially their original size and shape. In this manner, hollow microparticles  208  act as shock absorbers for the toner on roll  200  since hollow microparticles  208  are more compliant than toner particles thereby reducing the mechanical working applied to the toner and ultimately the damage incurred by the toner during the electrophotographic development process. 
     In the example embodiment illustrated, coating  206  is unground. However, a grinding operation may be applied to coating  206  in order to release some of the hollow microparticles  208  from coating  206  to form voids in coating  206  to further tune the surface roughness of coating  206 . 
     With reference to  FIG. 6 , a roll  300  for use in an electrophotographic image forming device, such as, for example a developer roll, is shown in cross section according to one example embodiment. Roll  300  includes an elastomeric core  302  mounted on a shaft  304 . Shaft  304  may be electrically conductive or non-conductive and may be composed of the materials discussed above with respect to shafts  104  and  204 . Like cores  102  and  202  discussed above, core  302  may be made of a thermoplastic or thermoset elastomeric type material that substantially recovers after an applied stress. Core  302  may be composed of the materials discussed above with respect to cores  102  and  202  and may include the conductive additives discussed above. Roll  300  includes hollow microparticles  306  dispersed within core  302 . Hollow microparticles  306  may have the properties and may be composed of the materials of hollow microparticles  106  and  208  discussed above. Portions of some of the hollow microparticles  306  of roll  300  extend beyond the outer circumference of core  302  and thereby provide a surface texture to core  302 . In contrast, hollow microparticles  106  of roll  100  are substantially contained within the outer circumference of core  102 . In one embodiment, roll  300  does not include a coating on core  302 . Instead, hollow microparticles  306  provide the surface topography directly. In another embodiment, a coating layer that does not include hollow microparticles is included on the outer surface of core  302  such that hollow microparticles  306  in core  302  translate through the coating to define the surface topography of roll  300 . The coating may be composed of the materials discussed above with respect to the optional coating of roll  100  and may include the curatives, fillers and conductive additives discussed above. 
       FIG. 7  is a schematic illustration of a process  3000  for manufacturing roll  300  according to one example embodiment. At step  3001 , the uncured elastomer of core  302  and hollow microparticles  306  in their unexpanded state are loaded into a mixing vessel  3010 . At step  3002 , the uncured elastomer and microparticles are mixed thoroughly to create a uniform dispersion  3012 . At step  3003 , the dispersed mixture  3012  is injected or otherwise loaded into a mold cavity  3014  in the shape of core  302 . At step  3004 , mold cavity  3014  is heated to a temperature sufficient to cure the elastomer but less than a minimum temperature at which hollow microparticles  306  permanently expand. At step  3005 , the molded component having cured elastomers is cooled and removed from mold cavity  3014 . At step  3006 , an external heat source such as, for example a UV or IR heat source, forced heated air, conduction by rolling on a hot plate, electromagnetic heating, etc., is used to heat the outer surface of the molded component above the minimum temperature at which hollow microparticles  306  permanently expand in order to permanently expand hollow microparticles  306 . Once the desired level of expansion is achieved, the component is cooled resulting in core  302  having hollow microparticles  306  extending beyond the outer circumference of the elastomeric portion of core  302  and providing a surface texture to core  302 . Core  302  may then be moved to any desired finishing operations such as, for example, a coating operation. Alternatively, a coating may be applied prior to expanding hollow microparticles  306  and the outer surface of roll  300  may be heated to cure the coating and to permanently expand hollow microparticles  306 . 
     The surface topography and roughness of roll  300  may be tailored to a desired value based on the concentration and size of hollow microparticles  306  included in core  302  and the heating temperature and duration. Where roll  300  is a developer roll, the surface topography may be tailored to achieve a desired toner mass flow. In one embodiment, the surface roughness (Ra) of roll  300  is between 0.1 and 5.0 μm including all values and increments therebetween. In one embodiment, the surface roughness (Rz) of roll  300  is between 0.1 and 25 μm including all values and increments therebetween. Hollow microparticles  306  act as shock absorbers for the toner on roll  300  thereby reducing the mechanical working applied to the toner and ultimately the damage incurred by the toner during the electrophotographic development process. Further, process  3000  provides a relatively simple process for manufacturing a roll having a tuned topography. Further, roll  300  may be more robust and less prone to wear issues than a comparable roll that uses beads or other particles in a coating layer to provide a desired surface topography. In addition, roll  300 , like roll  100 , has a lower mass in comparison with a roll having a solid core without hollow microparticles  106 . 
     In the example embodiment illustrated, core  302  is unground. However, a grinding operation may be applied to core  302  in order to release some of the hollow microparticles  306  to form voids in the outer surface of core  302  to further tune the surface roughness of core  302 . 
     The foregoing description illustrates various aspects of the present disclosure. It is not intended to be exhaustive. Rather, it is chosen to illustrate the principles of the present disclosure and its practical application to enable one of ordinary skill in the art to utilize the present disclosure, including its various modifications that naturally follow. All modifications and variations are contemplated within the scope of the present disclosure as determined by the appended claims. Relatively apparent modifications include combining one or more features of various embodiments with features of other embodiments.