JP2005189558A - Developing roller or its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems associated with a developing roller which is normally covered with a surface layer or the like to protect an elastic layer from physical or electric stimulus, in which the surface layer sometimes peels off from a tip part and the elastic layer is destroyed or damaged by the physical or the electric stimulus from another members. <P>SOLUTION: In the developing roller that is configured by stacking a single surface layer or a plurality of surface layers on the elastic layer provided around an electrically conductive shaft, the roller tip parts are covered by the surface layer whose film thickness is equal to 1μm or greater. Moreover, the covering characteristic of the roller tip parts is greatly improved by preliminarily heating and then applying the surface layer on the roller surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing roller incorporated in an apparatus employing an electrophotographic system such as a copying machine, a printer, or a facsimile receiving apparatus, or a manufacturing method thereof, and more particularly to a developing roller used in a developing apparatus employing a non-magnetic developing system or a manufacturing method thereof. About.

  In an apparatus employing an electrophotographic system, the developing roller has a function of conveying toner to an electrostatic latent image carrier such as a photosensitive member. FIG. 1 is an explanatory view schematically showing a general developing roller 10 used in a nonmagnetic developing system using a nonmagnetic one-component toner and its peripheral structure. The developing roller 10 is configured by concentrically laminating an elastic layer 12 around a conductive shaft 11 made of SUS or aluminum alloy, and covering the elastic layer 12 with a surface layer 13. The toner 15 stored in the toner container 14 is reliably carried on the surface of the developing roller by the supply roller 16 and is pressed by a regulating member 17 such as a regulating blade attached to the toner container 14 to be contact charged and frictionally charged. After the thin layer 18 is formed, the toner thin layer 18 adheres to the electrostatic latent image on the surface of the photoreceptor 19, thereby forming a toner image 20. In many cases, a DC voltage or an AC voltage is applied to the developing roller 10, the supply roller 16, and the regulating blade 17 in order to adjust the surface potential. Although the illustrated developing roller has its surface in contact with the photoconductor, some of the surface is not in contact with the photoconductor.

In order to protect the elastic layer from physical or electrical stimulation of the roller, such a developing roller is usually required to be completely covered with a surface layer, and spray, dipping, roll coating A method for creating a surface layer by various methods such as coating using a liquid as in a method has been reported so far (see, for example, Patent Document 1). However, these coating methods are generally used by diluting a resin or the like in an organic solvent, and it is difficult to coat the roller end due to the fluidity and surface tension of the coating solution. Further, the application by dipping and roll coating methods has problems such as difficulty in controlling the film thickness. As another method for creating a surface layer, formation of a surface layer tube by extrusion molding is known (see, for example, Patent Document 2). However, with this method, it is difficult to reduce the manufacturing cost, and Since it is necessary to increase the film thickness, the hardness of the roller inevitably increases.
Japanese Patent No. 3309621 Japanese Patent No. 3437627

  The developing roller is not only a physical impact due to contact with other members but also a member that is susceptible to an electrical impact. Due to the impact, the elastic layer material is destroyed and the end surface layer peels off when used for a long time. May occur. For this reason, it is necessary to relieve the load applied to the roller by the surface layer, and it is desired that the surface layer covers the roller surface to the roller end. The roller end referred to here means a portion having a width of 2 mm on each of the roller surface and the side surface from the roller corner.

  As a result of diligent research to achieve the above object, the present inventors have found that the surface layer peeling at the roller end occurs due to insufficient coating of the surface layer on the roller end. As a result, it was found that heating the roller in advance before coating the surface layer was effective for coating the roller end, and the developing roller of the present invention was achieved.

That is, according to the present invention, in a developing roller configured by laminating an elastic layer around a conductive shaft and a single or a plurality of surface layers on the elastic layer, a surface layer having a film thickness of 1 μm or more at the end of the roller. The coated developing roller (Claim 1), the developing layer (Claim 2), wherein the surface layer has a film thickness of 30 μm or less, the surface after the elastic layer is preheated A developing roller (Claim 3) on which a layer coating solution is applied and a surface layer is formed, a developing roller (Claim 4) at which the temperature of the elastic layer is preheated to 60 to 180 ° C, and the elastic layer The developing roller (Claim 5) having an Asker C hardness of 20 to 60 °, and the developing roller (Claim 6), wherein the application of the surface layer coating liquid is performed by spraying. ) And the elastic layer Then, after heating to 60 to 180 ° C., the surface layer coating solution is applied by spraying, whereby the roller end is coated with a surface layer having a film thickness of 1 μm or more (claim 7). ), The surface layer coating solution is constituted by diluting the resin or the like forming the surface layer with an organic solvent (claim 8), and the viscosity of the surface layer coating solution is: The developing roller manufacturing method is characterized in that it is 5 centipoise or more and 100 centipoise or less (claim 9).

  The roller manufacturing method of the present invention is expected to dramatically improve the durability of the roller.

  Hereinafter, embodiments of the developing roller according to the present invention will be described in detail.

  FIG. 2 is a cross-sectional explanatory view of an example of the developing roller 1 according to the present invention. The developing roller 1 is provided with an elastic layer 3 around a conductive shaft 2 made of SUS (stainless steel) having a diameter of about 1 mm to 25 mm, an aluminum alloy, or a conductive resin. The layer 4 is formed. If necessary, a resistance adjusting layer for adjusting the electric resistance of the developing roller, a primer layer for improving the adhesion between the elastic layer and the surface layer, or the like may be provided between the elastic layer and the surface layer. Layers may be arranged.

  The main component of the surface layer according to the present invention is preferably soluble in a solvent and can be applied from the viewpoint of ease of handling, and in particular, a polyol and an isocyanate are reacted with a chain extender as necessary. It is preferable that the resin is a polyurethane-based resin obtained by further comprising (1) a polyurethane-based resin in which one or both of a polyol and a chain extender contains a polysiloxane skeleton, and (2) a polyamine or the like in the chain extender. A polyurethane resin in which a urea bond is introduced or (3) a polyurethane resin obtained by reacting a polyol containing a polysiloxane skeleton with a chain extender containing polyamine or the like is used for wear resistance and toner charging. To preferred.

  The viscosity of the surface layer coating solution for forming the surface layer is preferably adjusted to 5 centipoise or more and 100 centipoise or less. When the viscosity is lower than 5 centipoise, the amount of the surface layer forming resin remaining after adhering is small, and the coating efficiency is poor. On the other hand, if it is higher than 100 centipoise, it is difficult to apply uniformly and the surface is likely to be uneven. When the viscosity of the resin forming the surface layer is higher than the above range, it is preferable to dilute with a solvent and adjust the viscosity.

  Examples of the method for forming the surface layer include dipping, spraying, roll coating, and brush coating according to the viscosity of the resin component constituting the surface protective layer, but a small amount of coating solution is applied to the elastic layer surface. In view of the fact that it is easy to make the solvent easy to volatilize, application by a spray method is preferable.

  The present inventor has determined that the surface of the end portion generated when the roller is used for a long period of time by setting the film thickness of the surface layer of the roller end portion (a portion having a width of 2 mm from the roller corner portion to the roller surface and the side surface) to 1 μm or more. It was possible to prevent layer peeling. However, in the conventional surface layer forming method, it was very difficult to cover the end of the roller due to the fluidity and surface tension of the coating solution (the surface layer was very formed at the corner between the roller surface and the side surface). It is hard to be done.) In particular, the lower the viscosity of the surface layer coating solution, the more difficult it was. On the other hand, the present inventor has found that the surface layer can be easily formed on the end of the roller by setting the surface temperature of the elastic layer roller before application of the surface layer to 60 to 180 ° C. When the surface layer is applied at 60 ° C. or lower, the volatilization of the coating solution solvent immediately after application tends to be insufficient, and the end coating is difficult to be formed. Further, if the temperature is 180 ° C. or higher, the solvent in the coating liquid bumps and is liable to cause defects such as bubbles on the roller surface, which is not preferable.

  The heating method for the elastic layer roller includes heating by an oven, hot air generator, heating by a shochu cake, etc., but the present invention does not particularly limit this method.

  The surface layer thickness of the roller end is preferably 1 μm or more from the viewpoint of durability of the roller end. On the other hand, the film thickness of the surface layer including the roller surface and the roller end is preferably 30 μm or less from the viewpoint of preventing the roller hardness from increasing.

  The developing roller according to the present invention includes a curable composition, other elastic materials such as urethane rubber, chloroprene rubber, and EP rubber, and a gold shaft having a conductive shaft made of, for example, a metal shaft made of SUS at the center. An elastic layer can be formed around the shaft by casting, injection, extrusion molding, and the like on the mold and heating and curing at an appropriate temperature and time (see JP-A-11-212354). In this case, it may be post-cured after semi-curing. The developing roller of the present invention is obtained by applying a resin constituting the surface layer to a predetermined thickness from above the elastic layer, and drying and curing at a predetermined temperature.

  The elastic layer preferably has an Asker C hardness of 20 to 60 ° so as not to damage surrounding parts such as a photoreceptor. Further, various conductivity imparting agents can be mixed for the purpose of imparting conductivity to the elastic layer.

  Hereinafter, specific Example 1 and Comparative Examples 1 and 2 of the developing roller according to the present invention will be described. In addition, these Examples do not limit this invention at all.

  As the elastic layer, a terminal allylated polyoxypropylene polymer ACX003 (manufactured by Kaneka Chemical Co., Ltd.) and a polysiloxane curing agent and a conductivity imparting agent (carbon black 3030B (manufactured by Mitsubishi Chemical Corporation)) were used. .

  The developing roller according to Example 1 and Comparative Examples 1 and 2 is provided with an elastic layer by thermally curing the elastic layer material having a thickness of 4 mm around a SUS shaft having a diameter of 8 mm. A surface layer was coated.

  The roller was heated by placing the elastic layer roller in an oven set at 140 ° C., then removing the roller and applying a surface layer after confirming that the temperature had dropped to a predetermined temperature with a surface thermometer.

  The surface layer was applied by using a hot airless spray system (manufactured by Nordson) by rotating a roller installed horizontally in the axial direction and spraying the application liquid at a liquid pressure of 4 MPa. The coating solution was dried by rotating in an oven set at 120 ° C. for 3 minutes. Thereafter, a heat treatment for removing the solvent at 160 ° C. for 90 minutes was performed to form a surface layer film.

  A scanning electron microscope (manufactured by JEOL, JSM-T100) was used for observation of the coating state of the roller end and film thickness measurement. The measurement sample was prepared by cutting the end of the roller about 5 mm in width and depositing copper. The surface layer film thickness was measured visually from the photographed image.

(Example 1)
1500 g of “N, N-dimethylformamide” was added to 500 g of urethane resin solution “Himlen Y-258” (manufactured by Dainichi Seika Co., Ltd.) and stirred well until the resin was dissolved. To this urethane resin diluted solution, 500 g of “methyl ethyl ketone” was added to 60 g of “carbon black 3030B”, and a sufficiently stirred suspension was added, followed by sufficient stirring to prepare a surface layer coating solution.

  This surface layer coating solution was applied by spray to an elastic layer roller heated to 60, 80, 100, and 120 ° C. in advance.

(Comparative Example 1)
The surface layer coating solution of Example 1 was applied to the elastic layer roller that had not been preheated by spraying.

(Comparative Example 2)
The elastic layer roller previously heated to 100 ° C. was dipped in the surface layer coating solution of Example 1 for coating.

  In all the examples, the film thickness of the surface layer in the roller axial direction was 10 μm or more. From Table 1, it can be confirmed that the end coverage is improved by preheating the roller. Further, in the dipping coating, the coating of the end portion could not be confirmed even when the surface temperature of the elastic layer roller was 100 ° C. However, the spray coating showed a film thickness of about 7 μm. It is confirmed that the spray method is preferable as a method for forming the film thickness of the roller end.

  In the durability test, the roller of the example and the comparative example was attached to a commercially available toner cartridge (manufactured by Canon Inc., EP-85 cartridge), and after printing 30,000 sheets, the state of the roller was observed visually and with a microscope. .

  For the roller of Example 1, no damage to the roller was observed in the durability test. On the other hand, in the rollers of Comparative Examples 1 and 2, scratches such as cracks were observed at the roller ends.

It is a schematic diagram which shows a developing roller and its peripheral structure. FIG. 3 is a cross-sectional explanatory view of a developing roller according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Conductive shaft 3 Elastic layer 4 Surface layer 10 Developing roller 11 Conductive shaft 12 Elastic layer 13 Surface layer 14 Toner container 15 Nonmagnetic toner 16 Supply roller 17 Restriction member 18 Toner thin layer 19 Photoconductor 20 Toner image

Claims (9)

  A developing roller comprising an elastic layer around a conductive shaft and a single or a plurality of surface layers laminated on the elastic layer, wherein the developing roller is covered with a surface layer having a film thickness of 1 μm or more at a roller end.   The developing roller according to claim 1, wherein the surface layer has a thickness of 30 μm or less.   The developing roller according to claim 1, wherein a surface layer coating liquid is applied after the elastic layer is preheated to form a surface layer.   The developing roller according to claim 3, wherein a temperature at which the elastic layer is preheated is 60 ° C. to 180 ° C. 5.   The developing roller according to claim 1, wherein the elastic layer has an Asker C hardness of 20 to 60 °.   The developing roller according to any one of claims 1 to 5, wherein the surface layer coating solution is applied by spraying.   In a method for producing a developing roller constituted by laminating an elastic layer around a conductive shaft and a single or plural surface layers on the elastic layer, the elastic layer is heated in advance to 60 to 180 ° C., and then the surface layer A method for producing a developing roller, wherein a coating liquid is applied by spraying to form a surface layer having a thickness of 1 μm or more at a roller end.   8. The method for producing a developing roller according to claim 7, wherein the surface layer coating solution is formed by diluting a resin or the like forming the surface layer with an organic solvent.   The method for producing a developing roller according to claim 7 or 8, wherein the viscosity of the surface layer coating solution is 5 centipoise or more and 100 centipoise or less.