JP2014081593A - Developing roll for one-component developing device, one-component developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing roll for a one-component developing device that suppresses the occurrence of fogging even after a repeated use.SOLUTION: A developing roll 42 for a one-component developing device has an outermost surface layer 42B formed of an insulating passive film on a base material 42A or a surface layer of a metal plating layer 42C provided on the surface of the base material 42A.

Description

  The present invention relates to a developing roll for a one-component developing device, a one-component developing device, a process cartridge, and an image forming apparatus.

As an image forming apparatus, a one-component developing device using a one-component developer (one-component toner) is known.
For example, in a one-component developing device, the surface of an aluminum substrate is alumite-treated, and a developing roll having an Al ₂ O ₃ insulating film disposed on the surface, or an insulating film made of α-Al ₂ O ₃ is formed by plasma irradiation. Developing rolls have been proposed (see, for example, Patent Documents 1, 2, and 3).

Japanese Patent Publication No. 3-14191, Japanese Patent Publication No. 3-14192 JP-A-5-142931

  An object of the present invention is to provide a developing roll for a one-component developing device that suppresses the occurrence of a phenomenon in which toner adheres to a non-image area (hereinafter referred to as “fogging”) even after repeated use.

The above problem is solved by the following means. That is, the present invention
The invention according to claim 1
A cylindrical or columnar substrate;
Provided on the surface layer of the substrate, an outermost surface layer composed of an insulating passive film,
A developing roll for a one-component developing device.

The invention according to claim 2
A cylindrical or columnar substrate;
A metal plating layer provided on the surface of the substrate;
Provided on the surface of the metal plating layer, the outermost surface layer composed of an insulating passive film,
A developing roll for a one-component developing device.

The invention according to claim 3
A one-component developing device comprising the developing roll according to claim 1.

The invention according to claim 4
An image carrier,
A developing device that develops, as a toner image, an electrostatic latent image formed on the image carrier using a one-component developer, comprising: a one-component developing device that includes the developing roll according to claim 1. ,
A process cartridge attached to and detached from the image forming apparatus.

The invention according to claim 5
An image carrier,
A charging device for charging the image carrier;
An electrostatic latent image forming apparatus for forming an electrostatic latent image on the charged image carrier;
A developing device that develops, as a toner image, an electrostatic latent image formed on the image holding member with a one-component developer, the one-component developing device including the developing roll according to claim 1 or 2, and the toner A transfer device for transferring an image to a recording medium;
A fixing device for fixing the toner image to the recording medium;
An image forming apparatus comprising:

  According to the first and second aspects of the invention, compared to the case where the outermost surface layer composed of an insulating passivating film is not provided, even for repeated use, for the one-component developing device that suppresses the occurrence of fogging. Development rolls are provided.

  According to the third, fourth, and fifth aspects of the present invention, even when used repeatedly, compared to the case where a developing roll having an outermost surface layer composed of an insulating passive film is provided, the occurrence of fogging A suppressed one-component developing device, a process cartridge, and an image forming apparatus are provided.

1 is a schematic configuration diagram illustrating a one-component developing device according to an exemplary embodiment. It is a schematic block diagram which shows the image development roll for one-component developing apparatuses which concern on this embodiment, (A) shows a 1st aspect, (B) shows a 2nd aspect. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the image forming apparatus which concerns on other this embodiment.

  Hereinafter, an embodiment which is an example of the present invention will be described in detail with reference to the drawings.

(Developer)
FIG. 1 is a schematic configuration diagram showing a one-component developing apparatus according to the present embodiment. 2A and 2B are schematic configuration diagrams showing a developing roll for a one-component developing device according to the present embodiment, in which FIG. 2A shows the first mode and FIG. 2B shows the second mode.

The one-component developing device (hereinafter referred to as “developing device”) 40 according to the present embodiment is a one-component developing device that performs development using, for example, a non-magnetic one-component developer (non-magnetic one-component toner). As shown in FIG. 4, a housing 41 containing a one-component developer 45A and partially opened is provided.
A developing roll 42 that protrudes from the opening and faces the electrophotographic photosensitive member 10 (an example of an image holding member) in contact with or non-contactingly and holds the one-component developer layer 45B on the surface, inside the housing 41; A developer supply roll 43 disposed in contact with the developing roll 42 and supplying the one-component developer 45A to the surface of the developing roll 42, and a one-component developer 45A supplied to the surface of the developing roll 42 by the developer supply roll 43 A layer regulating member 44 that forms a one-component developer layer 45B of a desired charge amount and layer thickness on the surface of the developing roll 42, and a stirring member 46 that stirs the contained one-component developer 45A; .
Note that the one-component developing device 40 according to the present embodiment includes a voltage applying device for applying a voltage to the developing roll 42, although illustration is omitted.

  Hereinafter, each element of the developing device 40 according to the present embodiment will be described in detail.

-Development roll-
First Embodiment As shown in FIG. 2A, the first embodiment of the developing roll 42 includes, for example, a cylindrical or columnar (cylindrical in this embodiment) base 42A and a surface layer of the base 42A. And an outermost surface layer 42B made of an insulating passive film.

In the developing roll 42 of the first aspect, examples of the base material 42A include a base material made of stainless steel (for example, austenitic stainless steel, ferrite stainless steel, two-phase stainless steel, etc.) or aluminum. Among these, the base material 42A is a base material made of austenitic stainless steel, ferritic stainless steel, or duplex stainless steel from the viewpoint of suppressing the occurrence of fogging by the passive film formed on the surface layer. Is good.
The outermost surface layer 42B is formed of, for example, an insulating passive film formed by passivating the surface layer of the base material 42A formed of these materials.

As the passivation of the substrate 42A, 1) surface treatment immersed in a solution such as a nitric acid solution, a potassium dichromate solution, or a sodium sulfide solution, 2) in a solution such as an alkali solution or a dichromate solution, Surface treatment for anodic electrolysis, 3) Heat treatment in an oxygen-existing atmosphere, etc.
Due to this passivation, the surface layer of the base material 42A, for example, the passivity of the material constituting the base material 42A (specifically, for example, if the base material 42A is stainless steel, the stainless passivity, that is, stainless steel) An insulating passive film containing an oxide of the alloy contained (e.g., an oxide of an alloy containing chromium, nickel, etc.) is formed, and this constitutes the outermost surface layer 42B.

The thickness of the base material 42A (thickness excluding the passive film on the surface layer) is, for example, when the shape is cylindrical. The thickness is preferably 1 μm or more, desirably 2 μm or more, and more desirably 5 μm or more.
The thickness of the insulating passive film (outermost surface layer 42B) formed on the surface layer of the substrate 42A is, for example, 0.01 μm or more and 10 μm or less, preferably 0.1 μm, from the viewpoint of suppressing the occurrence of fogging. It is not less than 5 μm and more desirably not less than 0.1 μm and not more than 2 μm.

-2nd aspect As shown in FIG.2 (B), the developing roll 42 of a 2nd aspect is 42 A of cylindrical or column-shaped (cylindrical form in this embodiment), for example on the surface of 42 A of base materials A metal plating layer 42C provided on the surface of the metal plating layer 42, and an outermost surface layer 42B provided on the surface of the metal plating layer 42C and made of an insulating passive film.

  In the developing roll 42 of the second aspect, examples of the base material 42A include a base material made of stainless steel (for example, austenitic stainless steel, ferrite stainless steel, two-phase stainless steel, etc.), nickel, or aluminum.

-Others Here, from the viewpoint of suppressing the occurrence of fog, the developing roll 42 of the first embodiment is an insulating non-conductive material formed by passivating the surface layer of the base material 42A made of stainless steel containing chromium and nickel. It is preferable to form a dynamic film and use the passive film as the outermost surface layer 42B.
On the other hand, from the viewpoint of suppressing the occurrence of fogging, the developing roll 42 of the second embodiment passivates the surface layer of the metal plating layer 42C composed of a chromium plating layer or a nickel plating layer to form an insulating passive film. It is preferable to form this passive film as the outermost surface layer 42B.
That is, in both the first and second developing rolls 42, the insulating passivating film (outermost surface layer 42B) passivates a metal or alloy containing at least one selected from chromium and nickel. It is good that it is the film which carried out.

-Developer supply roll 43-
Examples of the developer supply roll 43 include a sponge roll (for example, a urethane sponge roll) and a brush roll (for example, a conductive polypropylene brush roll and a conductive acrylic brush roll).

-Layer regulating member-
Examples of the layer regulating member 44 include rubber elastic blades (for example, blades of silicone rubber, urethane rubber, etc.) and metal blades (for example, blades of stainless steel, aluminum, phosphor bronze, etc.).
In addition, these blades, for example, are coated with 1) resin (for example, acrylic, phenol, urethane, or the like) or a resin in which molybdenum disulfide, melamine, graphite, or silicone acrylic is mixed with these resins. 2) A plate or tape (for example, a plate or tape made of acrylic, aluminum, Teflon (registered trademark), vinyl chloride, high-density polyethylene, polyoxymethylene, glass, or the like) may be used.

-Stirring member-
Examples of the stirring member 46 include a stirring member such as an agitator.

-Development method-
In the developing device 40 according to the present embodiment, for example, the one-component developer 45A stirred by the stirring member 46 is supplied to the surface of the developing roll 42 by the rotation of the developer supply roll 43 (in the direction of arrow A). When the one-component developer 45 </ b> A supplied to the developing roll 42 comes into contact with the layer regulating member 44 by the rotation of the developing roll 42 (in the direction of arrow B), it is regulated by the layer regulating member 44. When the one-component developer 45A is regulated by the layer regulating member 44, the one-component developer 45A (one-component toner) is charged to a target charge amount on the surface of the developing roll 42, and is layered with a target thickness. A component developer layer 45B is formed. When the one-component developer layer 45B reaches the opposite area (development area) of the electrophotographic photosensitive member 10 by the rotation of the developing roller 42 (in the direction of arrow B), the latent image formed on the electrophotographic photosensitive member 10 is developed. As a result, a toner image is formed.

-Action of developing device according to this embodiment-
The developing device 40 according to the present embodiment described above has the outermost surface layer 42B formed of an insulating passive film on the surface of the base 42A or the metal plating layer 42C provided on the surface of the base 42A. A developing roll 42 is provided.

  In the developing device 40 according to the present embodiment, the developing roll 42 has the outermost surface layer 42 </ b> B formed of an insulating passive film, thereby suppressing the occurrence of fogging even when used repeatedly. This is because when the outermost surface layer 42B of the developing roll 42 is formed of an insulating passive film, a single-component developer layer 45B of a desired charge amount and layer thickness is formed on the surface of the developing roll 42 by the layer regulating member 44. This is because it is considered difficult to be polished by the external additive of the toner contained in the one-component developer. In other words, this is because the polishing is unlikely to cause abrasion of the outermost surface layer 42B and maintains the insulating property, which is considered to suppress a decrease in the amount of charge applied to the toner.

  Further, in the developing device 40 according to the present embodiment, since the decrease in the amount of charge applied to the toner by the developing roll 42 is suppressed, it is considered that density unevenness is easily suppressed. In addition, since the outermost surface layer 42B of the developing roll 42 is difficult to be polished by the external additive of the toner, the uneven shape on the surface of the developing roll 42 is maintained, and a decrease in toner transportability is suppressed.

Here, conventionally, a developing roll having a porous γ-Al ₂ O ₃ layer formed by alumite treatment as the outermost surface layer is known, but this γ-Al ₂ O ₃ layer has a relatively low electric resistance. Since it has a low porous layer portion (porous layer portion), leakage occurs in the porous layer portion (porous layer portion) due to the voltage applied in the restriction region and the development region by the layer restriction member 44, The amount of charge applied to the toner is reduced, and fogging may occur. In addition, the chargeability of the toner may vary, and density unevenness may occur.
A developing roll having an α-Al ₂ O ₃ layer as the outermost surface layer is also known. However, the developing roll is easily polished by an external additive of the toner, and the surface of the developing roll is not maintained, and is applied to the toner. A reduction in charge amount may occur and fogging may occur. Further, the uneven shape on the surface of the developing roll is impaired, and the toner transportability is easily lost.
For this reason, the developing device 40 (developing roll 42) according to the present embodiment is particularly effective for these conventional techniques.

  The developing device 40 according to the present embodiment has been described with respect to the one-component developing device that performs development using a non-magnetic one-component developer (non-magnetic one-component toner). However, the developing device 40 uses a magnetic one-component developer (magnetic one-component toner). A one-component developing device that performs development may be used.

(Image forming devices, etc.)
FIG. 3 is a schematic configuration diagram illustrating the image forming apparatus according to the present embodiment.
As shown in FIG. 3, the image forming apparatus 101 according to the present embodiment includes an electrophotographic photosensitive member 10 (an example of an image holding member) that rotates clockwise as indicated by an arrow A, and an electrophotographic photosensitive member. The surface of the electrophotographic photosensitive member 10 provided on the surface of the electrophotographic photosensitive member 10 is provided above the body 10 to charge the surface of the electrophotographic photosensitive member 10, and the surface of the electrophotographic photosensitive member 10 charged by the charging device 20 is exposed. , An exposure device 30 (an example of an electrostatic latent image forming unit) that forms an electrostatic latent image, and a developing device 40 that develops the electrostatic latent image formed on the image carrier as a toner image with a one-component developer. And a transfer device 50 that transfers the toner image on the electrophotographic photosensitive member 10 to a recording paper P (an example of a recording medium), and a cleaning device 70 that cleans the surface of the electrophotographic photosensitive member 10.
The image forming apparatus 101 according to the present embodiment includes a fixing device 60 that fixes the toner image while conveying the recording paper P on which the toner image is formed.
The image forming apparatus 101 according to the present embodiment includes the developing device 40 according to the present embodiment as the developing device 40.

  Details of main components in the image forming apparatus 101 according to the present embodiment will be described below.

-Electrophotographic photoreceptor-
Examples of the electrophotographic photoreceptor 10 include an inorganic photoreceptor in which a photosensitive layer provided on a conductive substrate is made of an inorganic material, and an organic photoreceptor in which a photosensitive layer is made of an organic material. Organic photoreceptors include a functionally separated photoreceptor in which a charge generation layer that generates charges by conductive exposure and a charge transport layer that transports charges are stacked on a conductive substrate, or a charge on a conductive substrate. And a photoconductor provided with a single-layer type photosensitive layer in which the same layer performs the function of generating a charge and the function of transporting charges. Examples of the inorganic photoreceptor include a photoreceptor in which a photosensitive layer made of amorphous silicon is provided on a conductive substrate.
The shape of the electrophotographic photoreceptor 10 is not limited to a cylindrical shape, and a known shape such as a sheet shape or a plate shape may be employed.

-Charging device-
Examples of the charging device 20 include a contact charger using a conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, and the like.
Examples of the charging device 20 include a non-contact type roller charger and a known charger such as a scorotron charger using a corona discharge or a corotron charger.

-Exposure device-
Examples of the exposure apparatus 30 include optical system devices that expose the surface of the electrophotographic photoreceptor 10 with light such as semiconductor laser light, LED light, and liquid crystal shutter light imagewise. The wavelength of the light source is preferably within the spectral sensitivity region of the electrophotographic photoreceptor 10. The wavelength of the semiconductor laser is preferably near infrared having an oscillation wavelength of around 780 nm, for example. However, the present invention is not limited to this wavelength, and an oscillation wavelength laser in the 600 nm range or a laser having an oscillation wavelength of 400 nm to 450 nm as a blue laser may be used.
As the exposure device 30, for example, a surface-emitting laser light source of a multi-beam output type is also effective for color image formation.

-Transfer device-
As the transfer device 50, for example, a contact transfer charger using a belt, a roller, a film, a rubber blade or the like, or a known transfer charger such as a scorotron transfer charger using a corona discharge or a corotron transfer charger. Can be mentioned.

-Cleaning device-
The cleaning device 70 includes, for example, a casing 71, a cleaning blade 72, and a cleaning brush 73 disposed on the downstream side of the cleaning blade 72 in the rotation direction of the electrophotographic photosensitive member 10. Further, for example, a solid lubricant 74 is disposed in contact with the cleaning brush 73.

  Hereinafter, the operation of the image forming apparatus 101 according to the present embodiment will be described. First, the electrophotographic photoreceptor 10 rotates along the direction indicated by the arrow a, and at the same time is negatively charged by the charging device 20.

  The electrophotographic photoreceptor 10 whose surface is negatively charged by the charging device 20 is exposed by the exposure device 30, and a latent image is formed on the surface.

  When the portion where the latent image is formed on the electrophotographic photosensitive member 10 approaches the developing device 40, the developing device 40 attaches toner to the latent image and forms a toner image.

  When the electrophotographic photosensitive member 10 on which the toner image is formed is further rotated in the direction of arrow a, the toner image is transferred onto the recording paper P by the transfer device 50. As a result, a toner image is formed on the recording paper P.

  The toner image is fixed on the recording paper P on which the image is formed by the fixing device 60.

For example, as illustrated in FIG. 4, the image forming apparatus 101 according to the present embodiment includes an electrophotographic photoreceptor 10, a charging device 20, an exposure device 30, a developing device 40, and a cleaning device 70 in a housing 11. May be provided with a process cartridge 101 </ b> A in which are integrally stored. The process cartridge 101A integrally contains a plurality of members and is attached to and detached from the image forming apparatus 101.
The configuration of the process cartridge 101A is not limited to this. For example, the process cartridge 101A only needs to include at least the electrophotographic photoreceptor 10 and the developing device 40. In addition, for example, the charging device 20, the exposure device 30, the transfer device 50, and the cleaning At least one selected from the apparatus 70 may be provided.

  In addition, the image forming apparatus 101 according to the present embodiment is not limited to the above configuration, and is, for example, a cleaning device around the electrophotographic photosensitive member 10 and downstream of the transfer device 50 in the rotation direction of the electrophotographic photosensitive member 10. A first neutralization device may be provided on the upstream side of the rotation direction of the electrophotographic photosensitive member from 70 so that the polarity of the remaining toner is aligned and easy to remove with a cleaning brush. Alternatively, a configuration may be adopted in which a second static elimination device for neutralizing the surface of the electrophotographic photosensitive member 10 is provided on the downstream side in the rotation direction of the electrophotographic photosensitive member and on the upstream side in the rotational direction of the electrophotographic photosensitive member relative to the charging device 20. .

  The image forming apparatus 101 according to the present embodiment is not limited to the above-described configuration, and a known configuration, for example, a toner image formed on the electrophotographic photosensitive member 10 is transferred to the intermediate transfer member and then transferred to the recording paper P. An intermediate transfer type image forming apparatus or a tandem type image forming apparatus may be used.

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

Example 1
A metal roller made of SUS304 (stainless steel containing 18% Cr and 8% Ni) was immersed in a nitric acid solution and surface-treated for 30 minutes, thereby passivating the surface layer of the metal roller and increasing its thickness. An insulating passive film having a thickness of 1 μm was formed.
This metal roller was used as a developing roll.

(Example 2)
The surface of an aluminum metal roller was subjected to chromate treatment to form a passive film having an average thickness of 0.6 μm. This metal roller was used as a developing roll.

(Comparative Example 1)
An aluminum metal roller was anodized. As a result, an aluminum oxide layer (porous γ-Al ₂ O ₃ layer) having a thickness of 10 μm was formed on the surface layer of the metal roller.
This metal roller was used as a developing roll.

(Comparative Example 2)
An aluminum metal roller was plasma treated. As a result, an aluminum oxide layer (α-Al ₂ O ₃ layer) having a thickness of 2 μm was formed on the surface layer of the metal roller.
This metal roller was used as a developing roll.

(Comparative Example 3)
An aluminum metal roller was galvanized to form a 0.6 μm thick galvanized layer. This metal roller was used as a developing roll.

(Evaluation)
The developing roll obtained in each example was mounted on a non-magnetic one-component developing device obtained by modifying a developing unit of “Docu Print C3300” manufactured by Fuji Xerox Co., Ltd., and durability evaluation was performed by a continuous print test.
Specifically, a halftone image with an area coverage of 1% was continuously printed on A4 size paper, printed five sheets (noted as initial), 5000 printed (noted as 5 kpv), and 50,000 printed (noted as 50 kpv). At times, toner chargeability, toner transportability, fogging, and density unevenness of a solid image having an image density of 100% were evaluated.

-Toner chargeability-
The toner chargeability was evaluated by measuring the toner charge amount (q / g) as follows.
That is, the toner charge amount was measured by a suction method using a Faraday gauge having a suction nozzle and a filter and a coulomb meter.
Specifically, a masking jig having an opening area of 2.5 cm ² having the same curvature as the surface curvature of the developing roll is set on the developing roll, and the developer on the developing roll exposed to the masking opening is sucked into the suction roll. The amount of charge per unit area was calculated by measuring the amount of charge and measuring the increase in weight after suction, and using this as the toner charge amount.
The evaluation criteria are as follows.
○: The toner charge amount is less than −20 (q / g) −40 (q / g) or more Δ: The toner charge amount is less than −10 (q / g) −20 (q / g) or more ×: The toner charge amount is -10 (q / g) or more

-Toner transportability-
The toner transportability was evaluated by measuring the toner transport amount (g / m ² ) as follows.
The toner transport amount was measured by measuring the toner weight by sucking the toner on the surface of the developing roll by suction.
Specifically, a masking jig having an opening area of 2.5 cm ² having the same curvature as the surface curvature of the developer carrying member is set on the developing roll, and the toner on the sleeve exposed to the left masking opening is sucked by the nozzle. Thus, for the Faraday gauge, the difference in weight before and after suction was measured, and this was used as the toner conveyance amount.
The evaluation criteria are as follows.
○: Toner transport amount is 3.0 (g / m ² ) or more and 4.5 (g / m ² ) or less Δ: Toner transport amount exceeds 2.5 (g / m ² ) to 3.0 (g / m ² ) Less than x: Toner transport amount is 2.5 (g / m ² ) or less

-Cover-
The fog was evaluated by measuring the image density of the non-image area as follows.
A blank paper image is output by the evaluator (Docu print C3300), the evaluator is stopped during output, and the toner density on the photoconductor is measured using a reflection densitometer (X Rite 968, manufactured by X Rite, USA) The image density of the non-image area was measured.
The evaluation criteria are as follows.
○: Image density of non-image part is 0.02 or less Δ: Image density of non-image part is 0.025 or less ×: Image density of non-image part is 0.03 or less

-Density unevenness-
Density unevenness was determined by measuring the density of a printed 100% solid image with a reflection densitometer (XRite, manufactured by XRite, USA), measuring the difference in image density between the darkest part and the thinnest part. It is.
○: Image density difference is 0.2 or less △: Image density difference is 0.25 or less ×: Image density difference exceeds 0.25

  From the above results, it can be seen that in this example, better results were obtained for toner chargeability, toner transportability, fogging, and density unevenness as durability evaluation than the comparative example.

DESCRIPTION OF SYMBOLS 10 Electrophotographic photoreceptor 11 Case 20 Charging device 30 Exposure device 40 One-component developing device 41 Case 42 Developing roll 42A Base material 42B Outermost surface layer 42C Metal plating layer 43 Developer supply roll 44 Layer regulating member 45A One-component developer 45B One-component developer layer 46 Stirring member 50 Transfer device 60 Fixing device 70 Cleaning device 71 Housing 72 Cleaning blade 73 Cleaning brush 74 Lubricant 101A Process cartridge 101 Image forming device P Recording paper

Claims (5)

A cylindrical or columnar substrate;
Provided on the surface layer of the substrate, an outermost surface layer composed of an insulating passive film,
A developing roll for a one-component developing device. A cylindrical or columnar substrate;
A metal plating layer provided on the surface of the substrate;
Provided on the surface of the metal plating layer, the outermost surface layer composed of an insulating passive film,
A developing roll for a one-component developing device.   A one-component developing device comprising the developing roll according to claim 1. An image carrier,
A developing device that develops, as a toner image, an electrostatic latent image formed on the image carrier using a one-component developer, comprising: a one-component developing device that includes the developing roll according to claim 1. ,
A process cartridge attached to and detached from the image forming apparatus. An image carrier,
A charging device for charging the image carrier;
An electrostatic latent image forming apparatus for forming an electrostatic latent image on the charged image carrier;
A developing device that develops, as a toner image, an electrostatic latent image formed on the image holding member with a one-component developer, the one-component developing device including the developing roll according to claim 1 or 2, and the toner A transfer device for transferring an image to a recording medium;
A fixing device for fixing the toner image to the recording medium;
An image forming apparatus comprising:

Images