JP2011221150A - Rubber roller and image forming device - Google Patents

Abstract

Provided are a rubber roller suitable for a developing roller, a charging roller, or the like, which does not cause contamination of contact parts due to a vulcanizing agent, and an image forming apparatus in which image noise does not occur when an image is formed using the rubber roller.
A rubber roller having a metal core 1 and a rubber layer 2 made of a rubber composition on the metal core, the rubber composition being a rubber roller containing at least an epichlorohydrin rubber material and lignins. . An embodiment in which the lignin is any one of kraft lignin, lignin sulfonate, and lignophenol is preferable.
[Selection] Figure 1

Description

  The present invention relates to a rubber roller suitable for a developing roller, a charging roller, and the like, and an image forming apparatus using the rubber roller.

  A developing roller, a charging roller, a transfer roller, and the like used in an electrophotographic image forming apparatus are required to have uniform resistance and stability. In particular, in a one-component contact developing system capable of providing a small printer, a developing roller using a low hardness rubber agent is required to reduce friction stress on the developer.

  In order to stabilize the resistance, hydrin rubber which does not require uniform dispersion of a conductive material such as carbon black is advantageous. Further, silicone rubber is preferable for reducing the hardness. However, an insufficiently reactive oligomer component is generated in silicone rubber, and in order to suppress contamination of contact parts due to the surface of the oligomer component oozing out, surface coating is required, or special silicone rubber must be selected. Become. On the other hand, hydrin rubber which is advantageous in terms of resistance adjustment has its hardness adjusted by combining epichlorohydrin or a derivative thereof and a vulcanizing agent.

  However, conventional vulcanizing agents are low-molecular materials such as sulfur and sulfur-containing compounds, and inadequate vulcanizing agents ooze out on rubber surfaces under long-term use and temperature / humidity environments. There is a problem that image noise occurs during image formation.

In order to solve the above problems, for example, for the purpose of suppressing residual stress on the surface when the developing roller elastic layer is vulcanized, allyl glycidyl ether is contained, and at least sulfur and an organic sulfur compound are used as a vulcanizing agent. A production method for vulcanization molding using one kind has been proposed (see Patent Document 1).
However, even in this proposal, the problem of suppressing the bleeding of the vulcanizing agent has not been solved.

  In addition, it has been proposed to use a vulcanizing agent made of thioureas in order to suppress the compression set to a low level and to suppress the photoreceptor contamination (see Patent Document 2). However, in this proposal, thioureas have high hydrophilicity and low molecular weight, and there is a concern of seeping out under high temperature and high humidity.

  Accordingly, there is a demand for prompt provision of a rubber roller suitable for a developing roller, a charging roller, and the like, and an image forming apparatus using the rubber roller, which has excellent resistance stability and does not cause contact component contamination by a vulcanizing agent. Is the current situation.

  An object of the present invention is to solve various problems in the prior art and achieve the following objects. That is, the present invention provides a rubber roller suitable for a developing roller, a charging roller, or the like that does not cause contact component contamination with a vulcanizing agent, and an image forming apparatus that does not generate image noise when forming an image using the rubber roller. Objective.

  As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, the use of lignin as a vulcanizing agent for hydrin rubber makes it suitable for developing rollers, charging rollers, etc. that do not cause contamination of contact parts due to the vulcanizing agent. It has been found that a rubber roller can be obtained.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> In a rubber roller having a metal core and a rubber layer made of a rubber composition on the metal core,
The rubber composition is characterized in that the rubber composition contains at least an epichlorohydrin rubber raw material and lignins.
<2> The rubber roller according to <1>, wherein the rubber layer is obtained by vulcanizing a rubber composition in which lignin is mixed and dispersed in an epichlorohydrin rubber raw material.
<3> The rubber roller according to any one of <1> to <2>, wherein the lignin is any one of craft lignin, lignin sulfonate, and lignophenol.
<4> The epichlorohydrin rubber raw material contains at least one of a homopolymer of epichlorohydrin, a copolymer of epichlorohydrin and a binary or higher copolymer containing any one of alkylene oxide and unsaturated epoxide, and rubber other than epichlorohydrin rubber. The rubber roller according to any one of <1> to <3>.
<5> The rubber roller according to any one of <1> to <4>, wherein the rubber composition further contains a basic compound.
<6> The rubber roller according to any one of <1> to <5>, wherein the surface of the rubber layer is treated by either electron beam irradiation or ultraviolet irradiation.
<7> The rubber roller according to any one of <1> to <6>, wherein the surface of the rubber layer has a resin surface layer.
<8> The rubber roller according to any one of <1> to <7>, wherein the rubber roller is semiconductive.
<9> A developing roller comprising the rubber roller according to <8>.
<10> A charging roller comprising the rubber roller according to <8>.
<11> An image forming apparatus comprising at least one of the developing roller according to <9> and the charging roller according to <10>.

In the present invention, by using lignin as a vulcanizing agent for epichlorohydrin rubber, it is possible to provide a developing roller that does not cause contamination of contact parts due to the vulcanizing agent. The reason why this effect appears is as follows.
Lignins have a phenolic hydroxyl group, and this hydroxyl group is crosslinked by causing a substitution reaction with chlorine of epichlorohydrin rubber. Moreover, lignin is a polycondensation compound, and since the molecular weight is large, the mobility of the molecule is extremely small and no oozing out from the rubber layer occurs. Furthermore, since lignins have polar groups such as alcoholic hydroxyl groups and ether groups in addition to phenolic hydroxyl groups, it is considered that they can form a stable conductive path.

  According to the present invention, conventional problems can be solved, and contact noise caused by a vulcanizing agent does not occur. A rubber roller suitable for a developing roller, a charging roller, and the like, and image noise is generated during image formation using the rubber roller. It is possible to provide an image forming apparatus that does not.

FIG. 1 is a schematic sectional view showing an example of a rubber roller. FIG. 2 is a perspective view showing an example of a rubber roller. FIG. 3 is a schematic view showing an example of the image forming apparatus of the present invention. FIG. 4 is a schematic diagram of the process unit of FIG.

(Rubber roller)
The rubber roller of the present invention includes a cored bar and a rubber layer on the cored bar, and further includes other layers as necessary.

<Core>
The core metal is not particularly limited in its shape, structure, size, material, and the like, and can be appropriately selected according to the purpose. Examples of the shape include a cylindrical shape, and the structure. As for, a single layer structure may be sufficient and a laminated structure may be sufficient, and as said magnitude | size, it can select suitably according to the magnitude | size etc. of the said rubber roller.

  There is no restriction | limiting in particular as a material of the said metal core, It can select suitably according to the objective, For example, it can select and use suitably from carbon steel, alloy steel, cast iron, a conductive resin, etc. . Examples of the alloy steel include stainless steel, nickel chrome steel, nickel chrome molybdenum steel, chrome steel, chromium molybdenum steel, nitriding steel to which Al, Cr, Mo, and V are added. From the viewpoint, a metal one is preferable. Moreover, plating and oxidation treatment can be applied to the cored bar material as a rust prevention measure. As the plating, both electroplating and electroless plating can be used, but electroless plating is preferable from the viewpoint of dimensional stability.

<Rubber layer>
The structure, size, material and the like of the rubber layer are not particularly limited and can be appropriately selected according to the purpose. The structure may be a single layer structure or a laminated structure. The size may be appropriately selected according to the size of the rubber roller.

  The rubber layer contains an epichlorohydrin rubber raw material and lignins, and contains a basic compound and, if necessary, other components.

-Epichlorohydrin rubber raw material-
The epichlorohydrin rubber raw material includes (1) a homopolymer of epichlorohydrin, (2) a copolymer of two or more containing epichlorohydrin, alkylene oxide and unsaturated epoxide, and (3) other than epichlorohydrin rubber It is preferable to contain at least one of these rubbers.

Examples of the alkylene oxide include ethylene oxide and propylene oxide.
Examples of the unsaturated epoxide include allyl glycidyl ether, glycidyl methacrylate, glycidyl acrylate, and butadiene monooxide. Among these, allyl glycidyl ether is particularly preferable.

  Examples of the rubber other than the epichlorohydrin rubber include polyurethane rubber, silicone rubber, butadiene rubber, isoprene rubber, chloroprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, norbornene rubber, fluorine rubber, and acrylic rubber. These may be used individually by 1 type and may use 2 or more types together.

-Lignins-
The lignin is a polymer substance present as a plant vascular cell wall component, which is a complex condensation of phenylpropane-based structural units, and has a plurality of phenolic hydroxyl groups in the molecule, This hydroxyl group is crosslinked by causing an etherification reaction with the chlorinated alkyl group of the epichlorohydrin rubber raw material.
Since the lignin is a polycondensed compound and has a large molecular weight, the molecular mobility is extremely small, so that no bleeding from the rubber layer occurs. Moreover, since lignin has polar groups, such as alcoholic hydroxyl group and ether group, besides a phenolic hydroxyl group, it can form a stable conductive path.

The lignin is preferably any one of kraft lignin, lignin sulfonate, and lignophenol.
Examples of the lignin sulfonate include sodium lignin sulfonate, potassium lignin sulfonate, and calcium lignin sulfonate.
Among these, it is particularly preferable to use lignophenol in the presence of basic compounds such as calcium carbonate, calcium oxide, and magnesium oxide.
The content of the lignins is preferably 2% by mass to 25% by mass and more preferably 3% by mass to 20% by mass with respect to the total amount of the rubber composition. When the content is less than 2% by mass, rubber elasticity is not sufficiently imparted by crosslinking, and permanent permanent distortion may occur due to compression at the nip portion, which may cause image noise. 25% by mass If it exceeds 1, the rubber becomes too hard, so that a large compressive force is required to form the nip, and the torque may increase to rotate the developing roller and the photosensitive member, resulting in unstable driving.

-Basic compounds-
The basic compound promotes an etherification reaction (crosslinking) between the phenolic hydroxyl group of lignin and the chlorinated alkyl group of the epichlorohydrin rubber raw material. At that time, the basic compound has a function of trapping the generated hydrochloric acid, but a filler present in a solid form in the rubber layer is preferable in order to prevent the additive from exuding to the surface.
There is no restriction | limiting in particular as said basic compound, According to the objective, it can select suitably, For example, magnesium oxide, calcium oxide, calcium hydroxide, calcium carbonate, hydrotalcite, magnesium carbonate, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
The content of the basic compound is preferably 20% by mass or less, more preferably 2% by mass to 15% by mass with respect to the total amount of the rubber composition.

-Conductive agent-
There is no restriction | limiting in particular as said electrically conductive agent, According to the objective, it can select suitably, For example, an ionic conductive agent or an electronic conductive agent is used.
The ionic conductive agent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (for example, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium ( Perchlorate such as stearyltrimethylammonium), modified fatty acid dimethylethylammonium, lauryltrimethylammonium chloride, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, ethyl sulfate , Ammonium salts such as carboxylates and sulfonates, and perchlorates, chlorates and salts of alkali metals and alkaline earth metals such as lithium, sodium, potassium, calcium and magnesium Salts, bromates, iodates, fluoroboric acid salts, trifluoromethyl sulfate, and sulfonic acid salts.

  There is no restriction | limiting in particular as said electronic electrically conductive agent, According to the objective, it can select suitably, For example, conductive carbon, such as ketjen black and acetylene black: SAF, ISAF, HAF, FEF, GPF, SRF, FT, Carbon for rubber such as MT: Carbon for ink subjected to oxidation treatment, pyrolytic carbon, natural graphite, artificial graphite: conductive metal oxide such as tin oxide, titanium oxide, zinc oxide: nickel, copper, silver, germanium, etc. The metal of these can be mentioned. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular in the addition amount of the said electrically conductive agent, According to the objective, it can select suitably, In the case of an ionic electrically conductive agent, 0.01 mass part-5 mass parts are with respect to 100 mass parts of rubber components. Preferably, 0.05 mass part-2 mass parts are more preferable. In the case of an electronic conductive agent, 1 part by mass to 50 parts by mass is preferable with respect to 100 parts by mass of the rubber component, and 5 parts by mass to 40 parts by mass are more preferable.

  If necessary, the rubber composition may further contain other components such as a softening agent, a processing aid, an anti-aging agent, a filler, and a reinforcing agent.

There is no restriction | limiting in particular about the formation method of the said rubber layer, According to the objective, it can select suitably, For example, it can form with the manufacturing method of the rubber roller mentioned later.
The rubber layer may be prepared as solid rubber (hard rubber) or as sponge rubber (foamed rubber), and is appropriately selected according to the desired performance in the image forming apparatus to which the rubber roller of the present invention is applied. be able to.
There is no restriction | limiting in particular in the thickness of the said rubber layer, According to the objective, it can select suitably, For example, it is preferable that it is 1 mm-10 mm.

<Manufacturing method of rubber roller>
There is no restriction | limiting in particular as a manufacturing method of the said rubber roller, According to the objective, it can select suitably, For example, the mixing | blending component for manufacturing a rubber composition, and the additive mix | blended according to the use are rolls one by one. After mixing with a kneading machine normally used for kneading, such as a banbury mixer, kneader, etc., and covering the resulting rubber compound on the outer periphery of a metal core as a support shaft, press vulcanization molding or extrusion The rubber layer can be formed by applying a known method such as extrusion molding in which a roller is molded using a machine. Thereafter, in order to obtain a desired dimension and a uniform surface shape, the surface of the rubber layer is polished using a wet polishing machine, a dry polishing machine using a grindstone, or the like, if necessary.
If necessary, it is preferable to form a resin surface layer outside the rubber layer, or to treat the rubber layer surface with either electron beam irradiation or ultraviolet irradiation.

-Resin surface layer-
The resin surface layer is preferably formed of a resin material. As said resin material, a fluororesin, a silicone resin, a urethane resin, an acrylic resin etc. can be used conveniently, for example. Further, in order to reduce the change of the electric resistance value with respect to the thickness of the resin surface layer, it is preferable that the resistance value of the rubber layer and the electric resistance value of the resin surface layer are set as close as possible.

  Examples of the method for forming the resin surface layer include a method in which a resin material is applied to the rubber layer by a known coating method such as spray coating, electrostatic coating, dipping coating, or a tube-shaped resin material is applied to the rubber layer. A method of coating on the surface can be preferably employed.

The surface of the rubber layer is preferably treated with either electron beam irradiation or ultraviolet irradiation in terms of reducing the tackiness of the rubber surface or protecting the rubber surface.
As the electron beam irradiation treatment, for example, an electron beam irradiation device provided by NHV Corporation, Ushio Electric Co., Ltd., or Hamamatsu Photonics Co., Ltd. can be used. While rotating the roller, an acceleration voltage of 30 kV, Examples include a condition of irradiation for 1 minute in a nitrogen atmosphere at a tube current of 300 μA.
As the ultraviolet irradiation treatment, for example, a UV irradiation apparatus provided by Ushio Electric Co., Ltd. can be used, and while rotating a roller, an illuminance of 400 mW with a high-pressure mercury lamp with an emission wavelength of 250 nm, an integrated light quantity of 1,000 mJ / Examples include conditions of irradiating ultraviolet rays at cm ² .

  Here, FIG. 1 is a schematic sectional view of the rubber roller. FIG. 2 is a perspective view of the rubber roller. 1 and 2, 1 represents a cored bar and 2 represents a rubber layer. In addition, although illustration is abbreviate | omitted, you may have a resin surface layer on the rubber layer surface.

  The rubber roller of the present invention is excellent in resistance stability and does not cause contact component contamination with a vulcanizing agent. Therefore, the rubber roller is preferably used for a developing roller, a charging roller, and the like, and is preferably used for an image forming apparatus described below.

(Image forming device)
The image forming apparatus of the present invention includes at least an electrostatic latent image carrier (hereinafter also referred to as “electrophotographic photosensitive member” or “photosensitive member”), a charging unit, an exposing unit, and a developing unit. The image forming apparatus includes a transfer unit, a fixing unit, and other units appropriately selected as necessary, for example, a cleaning unit, a charge eliminating unit, a recycling unit, a control unit, and the like.

Here, the laser printer 100 as an example of the image forming apparatus of the present invention will be described.
First, the basic configuration of the printer 100 will be described. FIG. 3 is a schematic configuration diagram illustrating the printer 100. FIG. 4 is a schematic diagram of the process unit of FIG. As shown in FIGS. 3 and 4, the printer 100 includes yellow (hereinafter referred to as “Y”), cyan (hereinafter referred to as “C”), magenta (hereinafter referred to as “M”), and the like. Process units 1Y, 1M, 1C, and 1K are provided as four process cartridges for forming a color image from black (hereinafter referred to as “K”) toner. These use different colors of Y, M, C, and K toners as the developer, but otherwise have the same configuration and are replaced when the lifetime is reached. Since the four process units 1Y, 1M, 1C, and 1K have the same configuration, in FIG. 4, the process unit 1 is described with Y, M, C, and K omitted.

  As shown in FIG. 4, each process unit 1 includes a drum-shaped photoconductor 2 that is a latent image carrier, a photoconductor cleaning device 3, a charge eliminating device (not shown), a charging roller 4, a developing device 5, and the like. Yes. The process unit 1 can be attached to and detached from the main body of the printer 100, and consumable parts can be replaced at a time by releasing a stopper that prevents the printer 100 from unexpectedly falling off.

The photosensitive member 2 is rotationally driven at a linear speed of 150 mm / sec in the clockwise direction in the drawing by a driving means described later. The charging roller 4 is in pressure contact with the surface of the photoreceptor 2 and is driven to rotate by the rotation of the photoreceptor 2. Further, a high voltage is applied to the charging roller 4 by a high voltage power supply circuit (not shown) to charge the surface of the photoreceptor 2 to −500V.
The optical writing unit 70 serving as an exposure unit exposes image information to the photoconductor 2 to form an electrostatic latent image. For the optical writing unit 70, a laser beam scan using a laser diode, an LED, or the like is used.

  The developing device 5 is one-component contact development. A predetermined developing bias is supplied from a high voltage power source (not shown) to the developing roller 11 which is a developer carrying member provided in the developing device 5, and the electrostatic force on the photosensitive member 2. The latent image is visualized as a toner image. Then, intermediate transfer is performed on an intermediate transfer belt 16 described later. The photoconductor cleaning device 3 slides a cleaning brush or a cleaning blade on the surface of the photoconductor 2 to remove transfer residual toner attached to the surface of the photoconductor 2 after the intermediate transfer process.

A neutralization device (not shown) neutralizes residual charges on the photoreceptor 2 after cleaning. By this charge removal, the surface of the photoreceptor 2 is initialized and prepared for the next image formation.
Four process units 1 are arranged in parallel in the surface movement direction of the intermediate transfer belt 16 and form visible images in the order of yellow, cyan, magenta, and black. A primary transfer bias is applied to the primary transfer roller 19, and the toner image on the surface of the photoreceptor 2 is transferred to the surface of the intermediate transfer belt 16. The intermediate transfer belt 16 is moved endlessly in the direction of the arrow in FIG. 4 by a drive motor (not shown), and a visible image of each color is sequentially transferred onto the surface and superimposed to form a full color image. .

The full-color image formed on the intermediate transfer belt 16 reaches a secondary transfer nip that is a facing portion between the secondary transfer roller 20 and the secondary transfer portion facing roller 18. Then, when a predetermined voltage is applied to the secondary transfer roller 20, the image is transferred to the paper P that is a recording medium. The sheet P on which the image has been transferred is conveyed to the fixing device 34, where the full-color image is fixed on the surface thereof, and is stacked on the stack portion that is the upper surface of the upper cover 50 of the housing.
The toner remaining on the intermediate transfer belt 16 without being transferred to the paper P at the secondary transfer nip is collected by the transfer belt cleaning device 21.

  The developing device 5 includes a vertically long toner storage chamber 6 that stores toner (not shown) that is a nonmagnetic one-component developer, and a toner supply chamber 7 that is disposed below the toner storage chamber 6. Below the toner supply chamber 7, a developing roller 11 as a developer carrying member and a thinning blade 12 as a developer regulating member provided in contact with the developing roller 11 are provided. Further, a supply roller 15 that contacts the developing roller 11 and supplies developer to the developing roller 11 is provided. The developing roller 11 is disposed in contact with the photoreceptor 2 and is applied with a predetermined developing bias from a high voltage power source (not shown).

  A toner agitating member 8 is provided in the toner storage chamber 6 to flow the stored toner by rotating in the counterclockwise direction, and promotes the fall movement to the toner supply chamber 7 through the opening 9. To do. As shown in FIG. 4, the opening 9 is provided, a partition wall that partitions the toner storage chamber 6 and the toner supply chamber 7, and a toner guide member 14 that guides the toner that passes through the opening 9 is a supply roller. 15 is provided above. The closest distance between the toner guiding member 14 and the supply roller 15 is preferably larger than 0 mm and smaller than 5 mm.

The surface of the supply roller 15 is covered with a foam material having a structure having pores (cells), and the toner conveyed into the toner supply chamber 7 is efficiently attached and taken in, and the developing roller 11 and The toner is prevented from deteriorating due to pressure concentration at the contact portion. The foam material of the supply roller 15 is set to an electric resistance value of 1 × 10 ³ Ω to 1 × 10 ¹⁴ Ω.
A supply bias having a value offset in the same direction as the charging polarity of the toner is applied to the supply roller 15 with respect to the developing bias. The supply bias acts in a direction in which the toner preliminarily charged at the contact portion with the developing roller 11 is pressed against the developing roller 11.
However, the offset direction is not limited to this, and the offset may be zero (0) or the offset direction may be changed depending on the type of toner.

The supply roller 15 rotates in the counterclockwise direction, and applies and supplies the toner adhered to the surface to the surface of the developing roller 11. As the developing roller 11, a roller coated with an elastic rubber layer is used, and a surface coat layer made of a material that is easily charged to a polarity opposite to that of the toner is provided on the surface. The elastic rubber layer is set to have a MD-1 hardness of 65 ° or less in order to keep the contact state with the photoreceptor 2 uniform, and in order to further apply a developing bias, 1 × 10 ⁴ Ω. It is set to an electric resistance value of ˜1 × 10 ¹⁰ Ω. The surface roughness Ra is set to 0.2 μm to 2.0 μm, and the toner is held on the surface. The developing roller 11 rotates counterclockwise, and conveys the toner held on the surface to a position where the developing roller 11 and the thinning blade 12 face each other, and further to a position where the developing roller 11 and the photoreceptor 2 face each other. .

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Examples 1-10 and Comparative Examples 1-3)
The rubber composition for each roller shown in Table 1 was put into an open roller and kneaded to prepare a rubber compound.
The obtained rubber compound was wound around a stainless steel core having a diameter of 6 mm, placed in a cylindrical mold having a diameter of 14 mm, and subjected to primary vulcanization at 160 ° C. for 20 minutes.
After demolding the primary vulcanizate, secondary vulcanization was performed at 160 ° C. for 1 hour in an electric drying furnace to form a rubber layer.
After cooling the rubber layer, the surface of the rubber layer was polished with a grindstone grinder to adjust the outer diameter of the roller to 12 mm.
Furthermore, if necessary, the surface of the rubber layer was subjected to the surface treatment shown in Table 1, or a resin surface layer was formed, and rubber rollers of Examples 1 to 10 and Comparative Examples 1 to 3 were produced.

<Formation of resin surface layer>
10 parts by mass of polyurethane resin (D170N, solid content: 100% by mass, Mitsui Chemicals), 17 parts by mass of polyurethane resin (A2789, solid content: 40% by mass, manufactured by Mitsui Chemicals), conductive carbon black (10% by mass) Sprayed urethane resin coating liquid comprising 16 parts by mass of butyl acetate dispersion), 180 parts by mass of ethyl acetate, 20 parts by mass of butyl acetate, and 1 part by mass of resin particles (MB30X-20, manufactured by Sekisui Chemical Co., Ltd.) onto the rubber layer surface. Application was performed by a coating method to form a resin surface layer having a thickness of 20 μm.

<Surface treatment>
While rotating the sample to each rubber roller formed up to the rubber layer using a Min-EB apparatus manufactured by Ushio Electric Co., Ltd., conditions of acceleration voltage 30 kV, tube current 300 μA, irradiation distance 100 mm, nitrogen atmosphere 760 Torr, irradiation time 1 minute The electron beam irradiation was performed.

  Each rubber roller produced was set in the developing unit of a non-magnetic one-component development type laser printer (Ricoh Co., Ltd., IPSiO SPC310) shown in FIGS. 3 and 4, and various characteristics were evaluated as follows. It was. The results are shown in Table 1.

<Evaluation>
Each rubber roller of Examples 1 to 10 and Comparative Examples 1 to 3 was used as a developing roller and incorporated in the developing device 5 shown in FIG. 4, and a uniform thin toner layer was formed on the developing roller by running five blank sheets. Next, a black halftone image is printed after storage for 72 hours in a high-temperature and high-humidity environment of 90% RH at 50 ° C., and contamination of the surface of the photoreceptor from the developing roller appearing on the image is as follows. In addition, the occurrence of compression creep on the rubber surface of the developing roller was observed and evaluated according to the following criteria.

<Exudation contamination on the photoreceptor and presence or absence of compression creep on the rubber surface of the developing roller>
Exudation contamination on the photoreceptor was evaluated based on the following criteria by observing the presence or absence of white horizontal stripes at a circumferential length of the photoreceptor of 76 mm.
The presence or absence of compression creep on the rubber surface of the developing roller was evaluated based on the following criteria by observing the presence or absence of black horizontal stripes at a roller circumferential length of 27 mm pitch.
〔Evaluation criteria〕
○: No streaks △: Slight streaks are confirmed ×: Clear streaks are confirmed

* Hydrin H75: Epichlorohydrin homopolymer, manufactured by Nippon Zeon Co., Ltd. * Hydrin T3100: Epichlorohydrin-allyl glycidyl ether copolymer, manufactured by Nippon Zeon Co., Ltd. * Nipol 1042: Nitrile rubber, manufactured by Nippon Zeon Co., Ltd. * KL: Kraft lignin, INDULIN AT, Mead Westvaco Corp.
* LSNa: High purity high molecular weight sodium lignin sulfonate, Pearl Rex NP, manufactured by Nippon Paper Chemical Co., Ltd. * LSCa: High purity high molecular weight calcium lignin sulfonate, Pearl Rex CP, manufactured by Nippon Paper Chemical Co., Ltd. * LPh: Lignophenol, Lignophenol obtained by the method described in Example 1 of JP-A-2008-214231 * LCB: weakly conductive carbon black, Asahi # 15, manufactured by Asahi Carbon Co., Ltd. * HCB: conductive carbon black, Asahi # 78, * LTMA manufactured by Asahi Carbon Co., Ltd .: ionic conductive agent, lauryltrimethylammonium chloride, manufactured by Tokyo Chemical Industry Co., Ltd. * MgO: magnesium oxide, Kyowa Mag # 150, manufactured by Kyowa Chemical Industry Co., Ltd. * Hydrotalcite: DHT-4A, Manufactured by Kyowa Chemical Industry Co., Ltd. * Sulfur: End sulfur, Tsurumi Chemical Industry Co., Ltd. * ethylene thiourea: accelerator 22-S, Kawaguchi Chemical Industry Co., Ltd.

The rubber roller of the present invention can be suitably used as, for example, a developing roller, a charging roller, or a transfer roller.
The image forming apparatus of the present invention is suitable for an electrophotographic laser printer, a digital copying machine, a full-color copying machine, a full-color laser printer, and the like.

DESCRIPTION OF SYMBOLS 1 Process unit 2 Photoconductor 3 Hole sensitive body cleaning apparatus 4 Charging roller 5 Developing apparatus 6 Toner storage chamber 7 Toner supply chamber 8 Toner stirring member 9 Opening part 11 Developing roller 12 Thinning blade 14 Toner guide member 15 Supply roller 16 Intermediate Transfer belt 18 Secondary transfer portion facing roller 19 Primary transfer roller 20 Secondary transfer roller 21 Transfer belt cleaning device 34 Fixing device 50 Upper cover of housing 70 Optical writing unit 100 Printer

JP-A-8-110701 JP 2003-64251 A

Claims (11)

In a rubber roller having a metal core and a rubber layer made of a rubber composition on the metal core,
A rubber roller, wherein the rubber composition contains at least an epichlorohydrin rubber material and lignins.   The rubber roller according to claim 1, wherein the rubber layer is obtained by vulcanizing a rubber composition in which lignins are mixed and dispersed in an epichlorohydrin rubber raw material.   The rubber roller according to any one of claims 1 to 2, wherein the lignin is any one of craft lignin, lignin sulfonate, and lignophenol.   The epichlorohydrin rubber raw material contains at least one of a homopolymer of epichlorohydrin, a copolymer of epichlorohydrin and a binary or higher copolymer containing any one of alkylene oxide and unsaturated epoxide, and rubber other than epichlorohydrin rubber. The rubber roller according to any one of 1 to 3.   The rubber roller according to any one of claims 1 to 4, wherein the rubber composition further contains a basic compound.   The rubber roller according to any one of claims 1 to 5, wherein the surface of the rubber layer is treated with either electron beam irradiation or ultraviolet irradiation.   The rubber roller according to any one of claims 1 to 6, further comprising a resin surface layer on a surface of the rubber layer.   The rubber roller according to any one of claims 1 to 7, wherein the rubber roller is semiconductive.   A developing roller comprising the rubber roller according to claim 8.   A charging roller comprising the rubber roller according to claim 8.   An image forming apparatus comprising at least one of the developing roller according to claim 9 and the charging roller according to claim 10.