WO2004106051A1

WO2004106051A1 - Electrophotographie member and process for manufacturing same

Info

Publication number: WO2004106051A1
Application number: PCT/US2003/017629
Authority: WO
Inventors: Peter R. Rogge; Edward Weidert
Original assignee: Circular Technologies
Priority date: 2003-05-27
Filing date: 2003-05-27
Publication date: 2004-12-09
Also published as: WO2004106051A8

Abstract

An electrophotography member for use in electrophotography applications is provided. The electrophotography member is comprised of a monolithic elastic material layer (2b) comprised of at least a polyol, a polyisocyanate, and a hydroxyl-containing acrylate monomer, and additionally optionally comprised of some combination of a conductive additive, an ultraviolet absorber, and a photoinitiator, that is deposited on an electroconductive substrate (2a). The elastic material later (2b) is then exposed to ultraviolet light, thereby creating an electrically semi-conductive surface layer (2c). An electrophotography member prepared in this fashion has a hardness between about 5 and 50 Shore A durometer, a surface resistivity of between about 105 and 1012 Ohms/cm2 and a volume resistivity of between about 104 and 101° Ohms-cm.

Description

INTERNATIONAL APPLICATION FOR PATENT UNDER THE PATENT COOPERATION TREATY

ELECTROPHOTOGRAPHY MEMBER AND PROCESS FOR MANUFACTURING SAME

Inventors:

Peter Rogge

Edward Weidert

TECHNICAL FIELD [0001] This invention pertains to rollers used in electrophotography applications and, specifically, to an electrically conductive member having a surface with a significantly higher electrical resistivity than the substrate, said surface formed by exposing a monolithic member composed of a certain disclosed combination of materials to ultraviolet light, said members being particularly suitable for use as a charging or developing member.

BACKGROUND ART [0002] In an electrophotographic image-formation apparatus, for example, a laser printer, the following processes are performed, with reference to FIGS. 1 and 2:

1) A uniform distribution of electrical charges is applied through either a corona wire or contact charging roll 2 to an electrostatic latent image careying body 1 ;

2) An electrostatic image is formed on the image carrying body 1 by discharge of the desired print area through means such as a laser beam scanner, liquid crystal shutter array, a light emitting diode or the like 3;

3) The latent image is developed as a visible image with a developer or toner which is electrically charged to adhere to the desired print region of the image canying body by contact development via a charged developer roll 4;

4) The charged toner image is electrostatically transferred to a recording medium such as a sheet of paper or envelope via a charged transfer roll 5; 5) The transferred toner image is fused or otherwise fixed to the recording media through heat and pressure by means of a fuser roller 6 or the like;

6) Excess toner or other particulate is removed from the latent image carrying body by means of a cleaner blade and/or cleaning roller 7.

[0003] The latent image body 1 is typically in the form of a photoreceptive drum or photoconductor, and is typically a conductive tube la over which a charge generation layer lb is applied, followed by a charge transport layer lc. Other layers such as anodized or barrier layers may also be incorporated in this scheme.

[0004] The charging mechanism 2 can be a charge roller (as shown in FIGS. 1 and 2) charge blade, charge whiskers, or a corona wire. It is not desirable to use a corona wire as this method produces significant ozone emissions, which require a filter to minimize. The most common current method is to utilize a charging roller.

[0005] The development stage can comprise either contact or jump gap systems. The contact method places a coated developer roll 4 directly in contact with the photoreceptor or photoconductor 1 while a jump gap system will incorporate a conductive coated sleeve over a rotating magnet to present the toner to the photoreceptor.

[0006] For electrophotography applications, it is desirable to produce a roller having low hardness, in order to maintain a proper "nip width" between the photoconductor or photoreceptor and the various rollers. As such, electrophotography rollers are typically comprised of natural or synthetic rubber, thermoplastic elastomers, or urethanes.

[0007] It is also desirable to produce a roller having a volume electrical resistivity (also referred to as core electrical resistivity) of between about 10⁴ to 10¹⁰ Ohms -cm and a surface electrical resistivity of between about 10⁵ to 10¹² Ohms/cm². The desired differences between surface and volume resistivity are described in detail in U.S. Patent No. 5,017,965. Several methods are currently employed to achieve these desired electrical resistivities. For example, U.S. Patent No. 5,625,858 describes a method by which a pre-formed tube or sleeve is applied over a foam or solid semi- conductive polymer core. As another example, the invention disclosed in U.S. Patent No. 5,112,708 achieves the desired electrical resistivities by dip- or spray-coating a charging member core with N-alkoxymethylated nylon. However, it is both desirable and cost-effective to incorporate the coating materials within the roll itself, so as to provide a uniform layer of said higher electrically resistive material when completed.

[0008] Accordingly, to achieve these desired electrical resistivities in a polymer roller, conductive fillers are typically incorporated into the polymer matrix. However, when carbon blacks or metal oxides are used as fillers, the polymer is sufficiently hardened to prevent the deformation necessary to maintain a proper nip width between the photoconductor and the roller. It is possible to lower the hardness of such a polymer matrix via the introduction of plasticizers, such as pthalates or oils. Unfortunately, the leaching of these materials to the surface of the roller can cause damage to the photoconductor, resulting in print quality defects. In order to prevent such migration of plasticizer, and maintain a low hardness, chemically bonded acrylates can be incorporated into the polyurethane matrix for a charge roller as described in U.S. Patent No. 5,575,801. Alternatively, as described in U.S. Patent No. 6,042,946, a coating having both the desired hardness and electrical resistivities can be obtained by oxidizing the outer surface of a charge roller. The incorporation of acrylate in a polymer matrix has also been demonstrated in a resin coating composition for the surface layer of a developer roll as described in U.S. Patent No. 6,035,172.

[0009] Several parameters are considered in the design and manufacture of charging and developer rollers, respectively. Some parameters are unique to each type of roller, but several desirable properties are common to both inventions, such as the desire to provide a low hardness as to provide a wide nip between the roller and the photoreceptor. It is also desirable in both cases to have excellent mechanical wear properties, ozone resistance and minimized electrical variation between high and low humidity environments. Furthermore, the print quality performance of the system is best when a higher resistance coating over a more conductive core is employed in both cases.

[0010] There are specific differences between the two types of rollers. For example, a charging roller performs best when the surface is as smooth as possible to minimize localized charge differences. The surface roughness of a charging roller is considered in the previously mentioned U.S. Patent No. 6,337,103, and a theoretical value of 0.6 micron Ra or lower is widely accepted within the electrophotography industry as the desired roughness for best charging performance, while a developer roller will require a specific surface roughness to provide a mode of mechanical transfer for the toner as well as the electrical attraction between the toner particles and the developer roller itself. The best way to determine the required surface roughness for an application is to provide samples, which encompass the upper and lower limits of usability for required print quality, and evaluate the prints for optical density of the printed areas. Printed pages that provide a uniform black area, without background on white sections, are evaluated for isopel development and the proper roughness is determined. Typical acceptable surface roughness values for a developer roll will range between 0.3 and 2.0 microns Ra, as measured on a perthometer with 0.8 Newton force equipped with a 0.5 mm radius stylus.

DISCLOSURE OF INVENTION

[0011] According to the present invention, there is provided a contact charging member to be abutted against a photoreceptor and supplied with a voltage for charging the photoreceptor, comprising an electroconductive substrate and a surface layer of higher resisitivity provided by exposing said member, comprised of certain disclosed combinations of materials, to ultraviolet light. According to the present invention, there is also provided a contact developer member to be abutted against a photoreceptor and supplied with a voltage for transfer of toner from the developer member to the photoreceptor, comprising an electroconductive substrate, and a surface layer of higher resisitivity provided by exposure exposing said member, comprised of certain disclosed combinations of materials, to ultraviolet light.

[0012] In this invention, a bulk resistivity of the member is low relative to typical urethane values. The surface of the ultraviolet-treated member produces a surface layer of material with high electrical resistivity. The cost of production is low when compared to coating one of more separate outer layers, and the uniformity and roughness is superior to typical coatings currently used. In addition, very low hardness can be achieved when employing this method for member production. Furthermore, the present invention has improved performance under high humidity and high temperature conditions for the multi-layer charging member with a higher electrical resistive material at the outer surface of a charging member when compared with those of the prior art.

BRIEF DESCRIPTION OF DRAWINGS [0013] FIG. 1 is a side view schematic of a laser electrophotographic transfer system with cartridge-mounted charging and developer rolls according to this invention. f 0014] FIG. 2 is a side view schematic of a laser electrophotographic transfer system with a retracting machine-mounted charge roller and cartridge-mounted developer roll according to this invention. [0015] FIG. 3 is an elevational view of the electroconductive roller of the present invention. [0016] FIG. 4 is a cross-sectional view of the electroconductive roller of the present invention prior to exposure to ultraviolet light. [0017] FIG. 5 is a cross-sectional view of the electroconductive roller of the present invention following exposure to ultraviolet light. [0018] FIG. 6 is an illustration of a manner of measuring the volume resistance of an electroconductive roller. [0019] FIG. 7 is an illustration of a manner of measuring the surface resistivity of an electroconductive roller. [0020] FIG. 8 is a graphical representation of the change in the surface resistivity of an electroconductive roller, as a function of exposure time to ultraviolet light.

MODES FOR CARRYING OUT THE INVENTION [0021] An electrophotography member with a cross-section as shown in Fig. 4 is prepared. A charging or developer member according to the present invention is comprised of an electrically-conductive elastic material layer 2b fixed to the outer periphery of an electrically-conductive substrate 2a. [0022] The electrically-conductive substrate 2a acts as a supporting member for the completed electrostatic charging or developing member, and also as an electrode. It is typically a metal or alloy such as aluminum, copper alloy and stainless steel or an electrically-conductive material such as chromium or nickel-plated iron or synthetic resin. The outer diameter of the electrically-conductive substrate normally falls within the range of from 4 to 14 mm, particularly from 5 to 10 mm. [0023] The electrically-conductive elastic material layer 2b is comprised of at least the following materials:

1) A hydroxyl-containing acrylate monomer or a hydroxyl-containing acrylic acid, or a mixture thereof. Examples include hydroxy polyester acrylate, polypropylene glycol monomethacrylate, ethoxylated hydroxyethyl methacrylate, or a polyethylene glycol monomethacrylate such as CD572, a trademarked product of the Sartomer Company.

2) An unsaturated aliphatic polyisocyanate, an unsaturated cycloaliphatic polyisocyanate, or an unsaturated aromatic polyisocyanate, or a mixture thereof, or a prepolymer of isocyanate-terminated polyisocyanate with polyol. For example, an unsaturated aliphatic methylene diisocyanate with high NCO content, such as Mondur CD, a trademarked product of Bayer, Inc.

3) A multifunctional polyether polyol of high molecular weight that may or may not be ethylene oxide capped. For example, an ethylene oxide capped trifunctional polyol, such as Acclaim 6320, a trademarked product of Bayer, Inc.

[0024] The electrically-conductive elastic material layer 2b may optionally be further comprised of any combination of the following materials:

1) A conductive additive, such as organic salts, complexes of organic salts with polyols or glycols, electrically-conductive metal oxides, one or more of various metals or alloys, surface electrically-conductive insulating materials, in particulate form or mixtures thereof. For example, 0.25 to 2% by weight, ferric chloride salt complexed with oligoethylene glycol, in the form of tris (2,2'-oxybis(ethanoI)-02) fenic chloride, obtained from Eastman Kodak Co. Increasing the amount of conductive additive lowers the electrically-conductive elastic material layer 2b.

2) A multifunctional polyether curative of low molecular weight or a multifunctional amine, or a mixture thereof. For example, Curene 93, a trademarked product of Anderson Development Products, or Simulsol TOIE, a trademarked product of SeppicN.A., Inc. Increasing the amount of this constituent stabilizes the resulting polymer and increases its hardness. 3) An ultraviolet absorber, such as from the hydoxyphenyl benzotriazole , hydroxybenzophenone or piperidinyl sebacate classes, or from types of carbon black or metal oxide pigment-loaded colorants. For example, 0.15 to 2.0% by weight, liquid ultraviolet light absorber of the hydroxyphenyl benzotriazole class, Tinuvin 213, a trademarked product of Ciba Specialty Chemicals, Inc. Increasing the amount of ultraviolet absorber lowers the depth of the acrylate gradient in a member of the present invention.

4) One or more photoinitiators, such as 2,4,6, trimethylbenzophenone and 4- methylbenzophenone, oligomeric alpha hydroxy ketone , and 2-hydroxy-2- methyl-1-ρhenyl-l-propanone, or blends thereof. For example, 0.1 to 5% by weight each Sarcure SRI 137, and Sarcure SRI 129, both trademarked products of Sartomer, Co. The function of this material is to reduce the ultraviolet exposure time required to create an electrophotography member according to the present invention and thereby increase productivity.

[0025] The constituents of the polymer matrix can be manipulated in countless combinations to produce the electrical and mechanical properties necessary for a specific electrophotographic member application, or laser printer requirements. For example, an increase or reduction in the amount of conductive additive will result in a wide range of electrical volume resistivities, while changes in the hydroxyl fractional amount of low molecular weight multifunctional amine or polyol will result in a wide range of member hardnesses. Samples have been prepared without photoinitiators, which required an increase of twenty to fifty percent ultraviolet lamp exposure time, but still provide a smooth, tack-free surface similar to the results of parts incorporating the photoinitiator, but at the expense of productivity. Variations will be apparent and are anticipated.

[0026] The electrically-conductive elastic material layer 2b is provided to allow the electrophotographic member to have predetermined thickness, electrical resistivity, and hardness so that it can be pressed onto the surface of the material to be charged at a proper nip or nip pressure to make a uniform electrostatic charging of the surface of the material to be charged. The thickness of the electrically-conductive elastic material layer 2b may normally range from 0.5 to 6 mm, particularly from 2 to 4 mm. The volume resistivity of the electrically-conductive elastic material layer ranges from 10⁴ to 10¹⁰ Ohms-cm, and particularly from 10^s to 10⁹ Ohms-cm as measured on an apparatus depicted by FIG. 6. The hardness of the material can range between 5 and 50 Shore A, and particularly between 9 and 34 Shore A when measured from a molded one-half inch thick button of the cured polymer.

[0027] With reference now to FIG. 5, the resistance-controlling layer 2c of the present invention is comprised of a thin layer of acrylic-urethane formed by exposing the electrically-conductive elastic material layer 2b to an ultraviolet light.

[0028] The effect of the conversion of acrylate-urethane to acrylic-urethane is represented in FIG. 8, which shows the differences in surface resistivity for a roller prepared according to Example 1, and measured on a surface resistivity apparatus according to FIG 7 at three different ultraviolet exposure times. It is readily shown in FIG. 8 that the surface resistivity of the electrophotographic member is increased by two orders of magnitude from an unexposed core to the finished member. In addition, FIG. 8 illustrates the more stable electrical surface resistivity of the ultraviolet-treated roller in the initial 15 seconds of constant voltage application. The surface resistivity of the resistance-controlling layer ranges from 10⁵ to 10¹² Ohms/cm², and particularly from 10⁶ to 10^u Ohms/cm² as measured on an apparatus as depicted in FIG.7.

[0029] The electroconductive member is utilized within a laser printer cartridge, or as an integral part of the laser printer itself. FIG. 1 depicts the more prevalent method of utilization of both the developer roller and charge roller within the laser print cartridge, which is a self-contained electrophotography development unit. Within this configuration, it is expected the charge roll and developer roll to function within print quality acceptable limits for up to 14,000 prints. FIG. 2 depicts the less common incorporation of the charge roller within the machine, while the developer roller is an integral component of the laser print cartridge.

[0030] The present invention is described more specifically by way of the following Examples.

Example 1 [0031] A charge roller consistent with the cross-sectional description of FIG. 4 was prepared. [0032] A 6 mm diameter core la of nickel plated carbon steel 251 mm. in length was cleaned and coated with an electrically semi-conductive layer lb at a length of 229 mm and centered to the conductive shaft la.

[0033] For the purpose of facilitating electrical measurements, a 229 mm length of 8 mm conductive carbon tape, available from Ted Pella Inc., was applied axially to the core's outer surface. The core was then measured on a fixture consistent with FIG. 6 and values taken after a 10 second application of -100 Volts DC supplied by a Keithley 6517A resistance meter. A volume resistivity of 23 MegaOhms-cm was recorded. The core was placed in a fixture as illustrated in FIG. 7, and 100 Volts DC was applied to the core surface via a Beckman Megohmmeter. Measurements were taken at 45 seconds and the surface resistivity of 160 megaOhms/cm² was recorded. The roller was then cured and subsequently exposed to ultraviolet light in order to promote a conversion of acrylate-urethane surface to acrylic-urethane surface. The roller was re-measured on the bulk resistivity fixture to obtain a reading for volume resistivity of 54 MegaOhms-cm, and a surface resistivity of 24,000 MegaOhms/cm on the fixture for surface resistivity. The resisitivity of the roller surface was increased by two orders of magnitude, modifying the bulk resistivity of the roller to the predetermined target value.

[0034] More specifically, a 251 mm in length, 6 mm in diameter, carbon steel cylindrical shaft plated with nickel metal, was washed with soap and water, dried, and placed in a tubular stainless steel mold treated with polyurethane mold release, Stoner E236, available from Stoner. The mold was preheated to 200°F. While the mold was preheating, 69 grams of Acclaim 6320, 16 grams of CD572, 0.65 grams of AST-5, 0.73 grams of Curene, 0.7 grams of Tinuvin 213, 0.15 grams of Sarcure 1129, 0.15 grams Sarcure 1139, and 1 drop of AF9000, a degassing agent available from GE Silicones, were blended for 1 minute with constant stirring. To this mixture, 12.7 grams of Mondur CD, was added and blended for an additional 20 seconds to prepare 100 grams of liquid polymer. The resultant mixture was degassed, and 23 mL of the liquid polymer was transferred to the preheated steel mold. The mold was placed in an oven at 200°F for 15 minutes whereupon the liquid polymer was pre-cured to a solid polymer matrix. The solid core was then removed from the mold, and washed with soap and water to remove any excess mold release from the core. The roller was noted to be very tacky at this time.

[0035] The core was then exposed to an ultraviolet light source equipped with an "H" spectrum lamp, manufactured by UV Process Systems, and rated for 300 Watts per inch, at a focal distance of 3.5 inches from the lamp, and rotated at a rate of 7 rpm to provide uniform exposure of the core to the ultraviolet rays for a period of 75 seconds. The finished roller was recorded to have a durometer value of 18 Shore A. In addition, the tacky surface had been chemically converted to a smooth, glossy, tack-free polymer. The surface roughness was measured on a Mitutoyo Surtest 402 perthometer equipped with a 0.5 radius stylus under 0.8 Newton load. An average of 5 measurements, with a 10 mm range and cutoff wavelength of 0.8 nun, produced a value of 0.3 micron Ra.

[0036] The charge roll was then placed in a laser printer process cartridge, 27X, available from Hewlett-Packard, Inc., and the cartridge was then mounted in a laser printer, LJ4000, available from Hewlett-Packard, Inc. Print samples were produced in all- white, various gray-scales, and all-black exposures and evaluated for visual print quality. No defects such as spot, background toner development, pinhole or sanded image were noted, and the overall prints were acceptable and of high quality.

[0037] The cartridge was subjected to continuous lab ambient operation up to 32,000 pages printed, with samples of all-white, various gray-scales, and all-black exposures being printed every 1,000 prints. All samples were evaluated with no print quality defects noted over the length of the testing. In addition, the charge roll was inspected under magnification every 6,000 print cycles for evidence of cracking or degradation of the surface layer. No cracking was evident even at the end of the 32,000 page test.

Example 2 [0038] A charge roller was prepared in the same manner as Example 1 , except the sample was exposed to the ultraviolet lamp for 50 seconds. The volume resistivity was recorded as 38 MegaOhms-cm, and a surface resistivity of 1,800 MegaOhms/cm² on the fixture for surface resistivity. The resisitivity of the roller surface was increased by one order of magnitude, modifying the bulk resistivity of the roller to the lower predetermined target value.

[0039] The charge roll was then placed in a laser printer process cartridge, 27X, available from Hewlett-Packard, and the cartridge was then mounted in a laser printer, LJ4000, manufactured by Hewlett-Packard. Print samples were produced in all-white, various gray-scales, and all-black exposures and evaluated for visual print quality. No defects such as spot, background toner development, pinhole or sanded image were noted, and the overall prints were acceptable and of high quality.

[0040] The cartridge was subjected to continuous operation under elevated temperature and humidity (78°F, 80% relative humidity) to 32,000 pages printed, with samples of all- white, various gray-scales, and all-black exposures being printed every 6,000 prints. All samples were evaluated with no print quality defects noted over the length of the testing. In addition, the charge roll was inspected under magnification every 6,000 print cycles for evidence of cracking or degradation of the surface layer. No cracking or surface degradation was evident even at the end of the 32,000 page test.

Example 3

[0041] A charge roller was prepared in the same manner as Example 1, except the sample was prepared with 0.20 hydroxyl theory of Voranol 234-630, believed to be chemically identical to Curene 93. The fractional hydroxyl theory is the portion of total hydroxyl groups contributed to the overall polymer matrix by the constituent under scrutiny, and is understood by those skilled in the art of polyurethane chemistry. The initial volume resistivity was recorded to be 29 MegaOhms-cm, and a surface resistivity of 650 MegaOhms/cm² on the fixture for surface resistivity. The roller was then exposed for 50 seconds to the ultraviolet lamp and remeasured for electrical characteristics. The resisitivity of the roller surface was increased by two orders of magnitude, to a value of 26,000 MegaOhms/cm², modifying the bulk resistivity of the roller to the value of 48 MegaOhms-cm. In this case, the durometer of sample was measured as 23 Shore A.

[0042] The charge roll was then placed in a laser printer process cartridge, 27X, and the cartridge was then mounted in a laser printer, LJ4000, manufactured by Hewlett- Packard. Print samples were produced in all-white, various gray-scales, and all-black exposures and evaluated for visual print quality. No defects such as spot, background toner development, pinhole or sanded image were noted, and the overall prints were acceptable and of high quality.

Example 4

[0043] A charge roller was prepared in the same manner as Example 1, except the sample was prepared without the incorporation of a multifunctional amine or low molecular weight polyol, such as triisopropanolamine or Curene 93. The initial volume resistivity was recorded to be 21 MegaOhms-cm, and a surface resistivity of 380 MegaOhms/cm² on the fixture for surface resistivity. The roller was then exposed for 50 seconds to the ultraviolet lamp and remeasured for electrical characteristics. The resisitivity of the roller surface was increased by one order of magnitude, to a value of 5,000 MegaOhms/cm², modifying the bulk resistivity of the roller to the value of 22 MegaOhms-cm. In this case, the durometer of sample was measured as 9 Shore A.

[0044] The charge roll was then placed in a laser printer process cartridge, 27X, and the cartridge was then mounted in a laser printer, LJ4000, manufactured by Hewlett- Packard, Inc. Print samples were produced in all-white, various gray-scales, and all- black exposures and evaluated for visual print quality. No defects such as spot, background toner development, pinhole or sanded image were noted, and the overall prints were acceptable and of high quality.

Example 5

[0045] A charge roller was prepared in the same manner as Example 1, except the sample was prepared with 0.30 hydroxyl theory of Curene 93.

[0046] The initial volume resistivity was recorded to be 33 MegaOhms-cm, and a surface resistivity of 400 MegaOhms/cm on the fixture for surface resistivity. The roller was then exposed for 50 seconds to the ultraviolet lamp and remeasured for electrical characteristics. The resisitivity of the roller surface was increased by two orders of magnitude, to a value of 15,000 MegaOhms/cm², modifying the bulk resistivity of the roller to the value of 54 MegaOhms-cm. In this case, the durometer of sample was measured as 34 Shore A. [0047] The charge roll was then placed in a laser printer process cartridge, 27X, and the cartridge was then mounted in a laser printer, LJ4000, manufactured by Hewlett- Packard. Print samples were produced in all-white, various gray-scales, and all-black exposures and evaluated for visual print quality. No defects such as spot, background toner development, pinhole or sanded image were noted, and the overall prints were acceptable and of high quality.

Example 6

[0048] A charge roller was prepared in the same manner as Example 1, except the sample was prepared with 0.10 hydroxyl theory of triisoprolanolamine (TIP A), a tri- functional amine containing three hydroxyl groups per molecule, in lieu of 0.10 hydroxyl theory Curene 93. The initial volume resistivity was recorded to be 22 MegaOhms-cm, and a surface resistivity of 380 MegaOhms/cm² on the fixture for surface resistivity. The roller was then exposed for 50 seconds to the ultraviolet lamp and remeasured for electrical characteristics. The resisitivity of the roller surface was increased by two orders of magnitude, to a value of 12,000 MegaOhms/cm , modifying the bulk resistivity of the roller to the predetermined target value of 35 MegaOhms-cm. In this case, the durometer of sample was measured as 22 Shore A.

[0049] The charge roll was then placed in a laser printer process cartridge, 27X, available from Hewlett-Packard, and the cartridge was then mounted in a laser printer, LJ4000, manufactured by Hewlett-Packard. Print samples were produced in all-white, various gray-scales, and all-black exposures and evaluated for visual print quality. No defects such as spot, background toner development, pinhole or sanded image were noted, and the overall prints were acceptable and of high quality.

[0050] The cartridge was subjected to continuous operation under lowered temperature and humidity (60°F, 10% relative humidity) to 32,000 pages printed, with samples of all- white, various gray-scales, and all-black exposures being printed every 6,000 prints. All samples were evaluated with no print quality defects noted over the length of the testing. In addition, the charge roll was inspected under magnification every 6,000 print cycles for evidence of cracking or degradation of the surface layer. No cracking or surface degradation was evident even at the end of the 32,000 page test.

Example 7

[0051] A charge roller was prepared in the same manner as Example 6, except the sample was prepared with 0.20 hydroxyl theory of triisoprolanolamine.

[0052] The initial volume resistivity was recorded to be 29 MegaOhms-cm, and a surface resistivity of 440 MegaOhms/cm² on the fixture for surface resistivity. The roller was then exposed for 50 seconds to the ultraviolet lamp and remeasured for electrical characteristics. The resisitivity of the roller surface was increased by two orders of magnitude, to a value of 22,000 MegaOhms/cm², modifying the bulk resistivity of the roller to the value of 37 MegaOhms-cm. In this case, the durometer of sample was measured as 29 Shore A.

[0053] The charge roll was then placed in a laser printer process cartridge, 27X, and the cartridge was then mounted in a laser printer, LJ4000, manufactured by Hewlett- Packard. Print samples were produced in all-white, various gray-scales, and all-black exposures and evaluated for visual print quality. Defects were noted on all pages, the specific defect was noted as minor "cold-speckle" background and appears as very small repeating defects at charge roll intervals. Whereas these defects may not be noted by a casual look, it is apparent to a trained eye. The defects were attributed to a higher level of amine, providing nitrogen molecules at the surface, which can act as electron traps and is not conducive to high quality printing requirements. As this example illustrates, incorporation of amine containing cross-linking agents require care as to the amount of amine added, in order to prevent such undesirable print quality results.

Example 8 [0054] A developer roller consistent with the cross-sectional description as in FIG. 4 was prepared. [0055] An 8 mm diameter core 2a of nickel plated carbon steel 265 mm in length was cleaned and coated with an electrically semi-conductive layer 2b at a length of 229 mm and centered to the conductive shaft 2a.

[0056] The core was measured as in the previous examples, and a volume resistivity of 26 MegaOhms-cm was recorded, and a surface resistivity of 450 MegaOhms/cm² was recorded.

[0057] The roller was then cured and subsequently sanded, then exposed to ultraviolet light in order to promote a conversion of acrylate-urethane surface to acrylic-urethane surface. The roller was re-measured on the bulk resistivity fixture to obtain a reading for volume resistivity of 54 MegaOhms-cm, and a surface resistivity of 24,000 MegaOhms/cm² on the fixture for surface resistivity. The resisitivity of the roller surface was increased by two orders of magnitude, modifying the bulk resistivity of the roller to the predetermined target value.

[0058] More specifically, a 265 mm in length, 8 mm in diameter, carbon steel cylindrical shaft plated with nickel metal was washed with soap and water, dried, and placed in a tubular stainless steel mold treated with polyurethane mold release, Stoner E236, available from Stoner. The mold was preheated to 200°F. While the mold was preheating, 69 grams of Acclaim 6320, 16 grams of CD572, 0.65 grams of AST-5, 0.73 grams of Curene 93, 1.0 grams of Tinuvin 213, and 1 drop of AF9000, a degassing agent available from GE Silicones, were blended for 1 minute with constant stiπing. To this mixture, 12.7 grams of Mondur CD, was added and blended for an additional 20 seconds to prepare 100 grams of liquid polymer. The resultant mixture was degassed, and 35 mL of the liquid polymer was transferred to the preheated steel mold. The mold was placed in an oven at 212°F for 15 minutes whereupon the liquid polymer was pre-cured to a solid polymer matrix. The solid core was then removed from the mold, and washed with soap and water to remove any excess mold release from the core. The roller was noted to be very tacky at this time.

[0059] The roller was then placed in a lathe and rotated while being abraded with a wetted 400 grit sandpaper in order to modify the surface roughness, and promote mechanical transfer of toner particles to the photoconductor. An initial surface roughness was recorded as 0.4 micron Ra prior to wet-sanding.

[0060] The core was then exposed to ultraviolet light source; equipped with an "H" spectrum lamp, manufactured by UV Process Systems, and rated for 300 Watts per inch, at a focal distance of 3.5 inches from the lamp, and rotated at a rate of 7 ipm to provide uniform exposure of the core to the ultraviolet rays for a period of 100 seconds. The finished roller was recorded to have a durometer value of 20 Shore A. In addition, the roughened, tacky surface had been chemically converted to a smooth, matte, tackfree polymer with a surface roughness of 0.7 micron Ra.

[0061] The developer roll was then placed in a laser printer process cartridge, DR-250, available from Brother International Corporation, and the cartridge was then mounted in a laser copier, Brother Intellifax 2800, available from Brother International Corporation. This specific laser copier was selected for testing as the original developer roll has similar electrical characterizations as the previously produced charge rolls for demonstration of this invention as a developer roll. Print samples were produced in all-white, various gray-scales, and all-black exposures and evaluated for visual print quality. No defects such as spot, background toner development, pinhole or sanded image were noted, and the overall prints were acceptable and of high quality.

Claims

CLAIMS What is claimed:

1. An electrophotography member comprising an electroconductive substrate and an elastic material layer, said elastic material layer comprising a polyol, a polyisocyanate, and a hydroxyl-containing acrylate monomer, wherein said electrophotography member has been irradiated by ultraviolet radiation.

2. An electrophotography member according to claim 1, said elastic material layer additionally comprising a multifunctional polyether curative.

3. An electrophotography member according to claim 2, said elastic material layer additionally comprising a conductive additive.

4. An electrophotography member according to claim 3, said elastic material layer additionally comprising an ultraviolet absorber.

5. An electrophotography member according to claim 4, said elastic material layer additionally comprising a photoinitiator.

6. An electrophotography member according to claim 2, said elastic material layer additionally comprising an ultraviolet absorber.

7. An electrophotography member according to claim 6, said elastic material layer additionally comprising a photoinitiator.

8. An electrophotography member according to claim 2, said elastic material layer additionally comprising a photoinitiator.

9. An elecfrophotography member according to claim 1, said elastic material layer additionally comprising a multifunctional amine.

10. An electrophotography member according to claim 9, said elastic material layer additionally comprising a conductive additive.

11. An electrophotography member according to claim 10, said elastic material layer additionally comprising an ultraviolet absorber.

12. An electrophotography member according to claim 11, said elastic material layer additionally comprising a photoinitiator.

13. An electrophotography member according to claim 9, said elastic material layer additionally comprising an ultraviolet absorber.

14. An electrophotography member according to claim 13, said elastic material layer additionally comprising a photoinitiator.

15. An electrophotography member according to claim 9, said elastic material layer additionally comprising a photoinitiator.

16. An electrophotography member according to any one of claims 1-15, said elastic material layer having a hardness between 5 and 50 Shore A durometer.

17. An electrophotography member according to any one of claims 1-15, said elastic material layer having a surface resistivity of between about 10⁵ and 10¹² Ohms/cm .

18. An electrophotography member according to any one of claims 1-15, said elastic material layer having a volume resistivity between about 10⁴ and 10¹⁰ Ohms -cm.

19. An image-forming apparatus integrating an electrophotography member according to any one of claims 1-18.

20. A surface treatment method comprising the steps of: depositing an elastic material layer on an electroconductive substrate, said elastic material layer comprising a polyol, a polyisocyanate, and a hydroxyl-containing acrylate monomer; and irradiating said elastic material layer with ultraviolet radiation.

21. A surface treatment method according to claim 19, said elastic material layer additionally comprising a multifunctional polyether curative.

22. A surface treatment method according to claim 20, said elastic material layer additionally comprising a conductive additive.

23. A surface treatment method according to claim 21, said elastic material layer additionally comprising an ultraviolet absorber.

24. A surface treatment method according to claim 22, said elastic material layer additionally comprising a photoinitiator.

25. A surface treatment method according to claim 20, said elastic material layer additionally comprising an ultraviolet absorber.

26. A surface treatment method according to claim 24, said elastic material layer additionally comprising a photoinitiator.

27. A surface treatment method according to claim 20, said elastic material layer additionally comprising a photoinitiator.

28. A surface treatment method according to claim 19, said elastic material layer additionally comprising a multifunctional amine.

29. A surface treatment method according to claim 27, said elastic material layer additionally comprising a conductive additive.

30. A surface treatment method according to claim 28, said elastic material layer additionally comprising an ultraviolet absorber.

31. A surface treatment method according to claim 29, said elastic material layer additionally comprising a photoinitiator.

32. A surface treatment method according to claim 27, said elastic material layer additionally comprising an ultraviolet absorber.

33. A surface treatment method according to claim 31 , said elastic material layer additionally comprising a photoinitiator.

34. A surface treatment method according to claim 27, said elastic material layer additionally comprising a photoinitiator.

35. A surface treatment method according to claim 19, additionally comprising the step of cleaning said electroconductive substrate.

36. A surface treatment method according to claim 19, additionally comprising the step of applying a conductive tape to said electroconductive substrate.

37. A surface treatment method according to claim 19, additionally comprising the step of curing said elastic material layer.

38. A surface treatment method according to claim 19, additionally comprising the steps of: placing said elecfrophotography member in a mold; heating said electrophotography member and said mold; removing said electrophotography member from said mold; and cleaning said electrophotography member.

39. A surface treatment method according to claim 37, additionally comprising the step of preheating said mold.

40. A surface treatment method according to claim 19, additionally comprising the step of abrading said elastic material layer.

41. A surface treatment method according to claim 19, additionally comprising the step of rotating said electrophotography member during said step of irradiating said elastic material later with ultraviolet radiation.