JP2002040756A - Image forming device, process cartridge, toner and electrifying member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device equipped with an electrifying member constituted so that toner and additive agent may hardly stick to the surface of the electrifying member, and also with toner which hardly stick to the surface of the electrifying member, and introducing a simultaneous developing and cleaning system or a cleaner-less system where the occurrence of the defective image due to the sticking of the toner and the additive agent to the electrifying member is prevented, and where the durability and stability are improved. SOLUTION: A contact-electrifying system image forming device is constituted by using the electrifying member which is formed to a shape of a roller having a conductive supporting body and one or more coating layers formed on the conductive supporting body, and having a roller whose run out of outer diameter difference is equal to or below a roller crown amount, and also, having a surface static frictional coefficient of <=1.0, and also, having a surface roughness (Rz) of <=5 μm, and the toner including organic fine powder as toner particles and additive agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus, a process cartridge, and a developer and a conductive member used in the electrophotographic apparatus, and more particularly, to an image forming apparatus employing an electrophotographic system such as a printer, a facsimile, and a copying machine. The present invention relates to a conductive member for electrically controlling an object to be contacted, such as a charging member, a developer carrying member, a transfer member, a cleaning member, and a charge removing member in an apparatus. More specifically, a charged member to which a voltage is applied is brought into contact with the object to be charged. And a contact charging member for charging an object to be charged.

[0002]

2. Description of the Related Art For convenience, an image forming apparatus such as a laser beam printer, a copying machine, and a facsimile of an electrophotographic system will be described as an example. 2. Description of the Related Art An electrophotographic image forming apparatus generally uses a rotating drum type photoconductor using a photoconductive substance as an image carrier. A) The rotating photoconductor surface is charged to a predetermined polarity and potential by a charging unit. A charging step of uniformly and uniformly charging b) exposing the uniformly charged surface of the rotating photoreceptor to image information by image exposure means (laser beam scanning exposure means, current image projection and image formation exposure means, etc.) C) a developing step of developing the formed electrostatic latent image as a toner image by a developing unit d) a transfer material such as paper from the photoreceptor side by the transferring unit from the photoreceptor side E) a fixing step of fixing the toner image of the transfer material separated from the photoreceptor to the surface of the transfer material by fixing means with heat or pressure, etc. f) a toner image transferred to the photoreceptor surface after the transfer of the toner image onto the transfer material By removing the toner remaining to execute the image forming by a cleaning step for cleaning the photoreceptor surface and the image forming material (copies, prints) without those obtained. The cleaned photoreceptor is repeatedly used for image formation. A) to above
Various methods and configurations are specifically known as each step and means of f).

In recent years, the size of such an image forming apparatus has been reduced. However, in some cases, it is not sufficient to reduce the size of the image carrier and each of the processing means constituting the apparatus. Further, the toner remaining on the photoreceptor surface after the transfer of the toner image to the transfer material is removed by cleaning means (cleaning device) and becomes waste toner. From the viewpoint of ecology, the waste toner is effectively used. A system that does not discharge toner has been desired.

[0004] As an essential cleaning device as a dedicated device for removing toner remaining on the photoreceptor after the transfer step, devices such as a blade cleaning system, a fur brush cleaning system, and a roller cleaning system are conventionally used. However, in any case, a cleaning member such as a blade, a fur brush, or a roller is brought into contact with the surface of the photoreceptor to mechanically scrape off or transfer the residual toner and collect it in a waste toner container. Also, there is a problem caused by such a cleaning member being pressed against the surface of the photoreceptor. For example, it is possible to rub the photoconductor by strongly pressing the cleaning member to shorten the life of the photoconductor.

Therefore, by using the developing means also as a cleaning means for the toner remaining on the surface of the photoreceptor after the transfer of the toner image to the transfer material, it is possible to carry out the simultaneous cleaning or development without the provision of the cleaning means as a dedicated device. An image forming apparatus called cleaner-less has also appeared (JP-A-59-133573, JP-A-62-203).
Nos. 182, 63-133179 and 64-
20587, JP-A-2-51168, 2
JP-A-302772, JP-A-5-2289, and 5-
No. 53482, No. 5-61383, etc.).

In the simultaneous cleaning with development, the transfer residual toner on the photoconductor is transferred from the transfer section to the development section, and is applied to the toner carrier by the toner carrier (developing member) of the developing means at the time of development after the next step. The fog removal potential difference Vback, which is a potential difference between the DC voltage and the photoconductor surface potential, is collected. According to this, even if there is no cleaning device as a dedicated device, the transfer residual toner is collected by the developing unit and used for the development after the next process, so that the waste toner can be eliminated. Further, since there is no need to provide a cleaning device as a dedicated device, there is a great advantage in terms of space, and the size of the image forming apparatus can be significantly reduced.

Conventionally, in an electrophotographic image forming apparatus, a high voltage (DC voltage of 6 to 8 kV) is applied to a metal wire as a charging means for uniformly charging the entire surface of a photoreceptor as a member to be charged. And a corona discharger that charges the photoreceptor surface by a generated corona shower has been widely used. This corona discharger is effective as a means for uniformly charging the photoreceptor to a certain potential, but conversely, the charging process by corona discharge requires a high-voltage power supply, Ozone is generated in large quantities. When a large amount of ozone is generated, the environment may be adversely affected, and the charging member and the photoconductor are deteriorated by the ozone.

A contact charging system has been put to practical use in which a voltage is applied to the corona discharger while the charging member is in contact with the photosensitive member to charge the surface of the photosensitive member. this is,
The photosensitive member is brought into contact with a charging member as a charge supply member such as a roller type, a blade type, a brush type, and a magnetic brush type,
A predetermined bias is applied to the contact charging member to uniformly charge the photoreceptor surface. This charging method has the advantage that the voltage of the power supply can be reduced and the amount of ozone generated due to the charging process is small. In addition, there is an advantage that there is no electrostatic attraction of dust associated with the use of the corona electrode wire, and a high voltage power supply is not required. Among them, a roller charging method using a conductive roller (charging roller) as a contact charging member is particularly preferably used from the viewpoint of charging stability.

More specifically, since the charging is performed by discharging from the charging member to the member to be charged, the charging is started by applying a voltage higher than a certain threshold voltage. For example, when the charging roller is pressed against the OPC photosensitive member having a thickness of 25 μm, the surface potential of the photosensitive member starts to increase when a voltage of about 600 V or more is applied, and thereafter, The surface potential of the photoconductor increases linearly at a slope of 1 with respect to the applied voltage. Hereinafter, this threshold voltage is defined as a discharge start voltage (charge start voltage) Vth. That is, in order to obtain the photoconductor surface potential Vd (dark portion potential) required for electrophotography, the charging roller needs a direct current voltage (DC voltage) of Vd + Vth which is higher than the required potential Vd. In this way D
A system in which only the C voltage is applied to the contact charging member to perform charging is referred to as a “DC charging system”.

Further, as disclosed in Japanese Patent Application Laid-Open No. 63-149668, an AC voltage component having a peak-to-peak voltage of twice or more of Vth in a DC voltage corresponding to a desired surface potential Vd of a member to be charged. An “AC charging method” in which a voltage on which an AC voltage component is superimposed is applied to a contact charging member is also used. This is due to the potential smoothing effect of the AC voltage,
The potential of the member to be charged is the potential V at the center of the peak of the AC voltage.
This is an excellent contact charging method that converges to d and charging is not affected by external conditions such as the environment.

Further, a charge injection layer (charge layer) is provided on the surface of the image bearing member as a member to be charged, and the charge is directly injected into the charge injection layer by a contact charging member to which the charge has been applied, so that the image bearing member is charged. There is also an injection charging method for charging the body surface to a predetermined polarity and potential, which is also a category of contact charging.

Among these, in an image forming apparatus employing a simultaneous development cleaning system (cleanerless system),
It is considered preferable to employ the “DC charging method”.

Conventionally, a charging roller has a resistance layer provided on a conductive support, or has at least an elastic layer and a resistance layer provided on a conductive support, and maintains an appropriate volume resistance in the upper resistance layer. By maintaining the lower elastic layer with appropriate elasticity to make proper contact with the member to be charged, the uniformity of charging of the member to be charged can be improved, and the pinhole on the surface of the member to be charged such as a photoreceptor can be improved. The prevention of leaks due to scratches and the like has been attempted.

As the elastic layer, a layer in which conductive powder such as carbon black, graphite, metal powder and metal oxide is dispersed in an elastic material is used. Elastic materials include ethylene propylene rubber (EPDM), styrene butadiene rubber (SBR), chloroprene rubber (CR), nitrile butadiene rubber (NBR), butyl rubber (BR), isoprene rubber (IR), epichlorohydrin rubber (CO, EC
O), synthetic rubbers such as urethane rubber (U) and silicone rubber, natural rubber (NR), styrene butadiene styrene (SRS), polyolefin-based and polyurethane-based thermoplastic elastomers, and mixtures thereof.
The elastic layer contains a considerable amount of conductive fine powder in the elastic material in order to reduce the required resistance, but the mixing of a large amount of conductive fine powder results in an increase in the hardness of the elastic material. A considerable amount of softening oils and plasticizers are blended to reduce this. The elastic layer is often formed by molding or the like.

As the resistance layer, a layer in which conductive particles such as carbon black and metal oxide are dispersed in a polymer compound such as a polyamide resin, a polyurethane resin, an acrylic resin and a fluororesin is used. The resistance layer is often formed by dip coating, spray coating, roll coating, or the like.

[0016]

In the roller charging system, since the charging roller is in contact with the photosensitive member, there is a problem that the surface of the roller is easily stained. That is, even if the cleaning process of the photoconductor drum is completed, if a small amount of residual toner and external additives exist on the photoconductor drum,
They adhere to the surface of the charging roller that is driven and rotated by the photosensitive drum, and the roller surface becomes dirty. As a result, the resistance value of the roller increases, and the photosensitive member cannot be charged uniformly, resulting in uneven density on the image. Such toner and external additives on the surface of the charging roller have been issues for improving the image quality and durability of the image forming apparatus.

In particular, when a conventional charging roller is mounted on a cleaner-less type image forming apparatus, there is a problem that toner and external additives remaining on the photoreceptor are likely to adhere.
That is, in the cleanerless method, the photoconductor is charged by the charging roller in a state where the untransferred residual toner and the external additive are present on the photoconductor, so that the toner and the external additive easily adhere to the charging roller. This causes problems in image quality and durability. In particular, in a low-temperature and low-humidity environment, image fogging and image density unevenness caused by the adhesion of toner and external additives are remarkable, which is a problem. In addition, in the DC charging system, there is a tendency that a charging failure due to the stain unevenness is more likely to occur than in the AC charging system.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus which does not cause an image defect due to adhesion of a toner and an external additive to a charging roller. Another object of the present invention is to provide an image forming apparatus employing a simultaneous development cleaning method or a cleanerless method. Another object of the present invention is to provide an image forming apparatus having excellent durability stability. It is another object of the present invention to provide an image forming apparatus having a charging member to which toner and external additives hardly adhere to the surface of the charging member. It is a further object of the present invention to provide an image forming apparatus having a toner that does not easily adhere to the surface of a charging member.

[0019]

The present invention is characterized by the following constitution. (1) a photoreceptor, charging means for charging the photoreceptor by a charging member in contact with the photoreceptor, exposure means for exposing the charged photoreceptor to form an electrostatic latent image on the photoreceptor, Developing means for supplying toner to the photoreceptor having the electrostatic latent image formed thereon to form a toner image corresponding to the electrostatic latent image on the photoreceptor; transfer means for transferring the toner image on the photoreceptor to a transfer material; In the image forming apparatus having, the charging member is a conductive support,
A roller having at least one coating layer formed thereon is formed in a roller shape, and the roller outer diameter difference fluctuation of the charging member is equal to or less than a roller crown amount of the charging member, and a static friction coefficient of a surface of the charging member. Is 1.0 or less, and the surface roughness (Rz) of the charging member is 5 μm or less.

(2) In a process cartridge detachably mounted on the main body of the image forming apparatus, the process cartridge comprises a photosensitive member, a charging means for charging the photosensitive member by a charging member in contact with the photosensitive member, and Developing means for supplying toner to the electrostatic latent image formed on the photoconductor and forming a toner image corresponding to the electrostatic latent image on the photoconductor, wherein the charging member is a conductive support And a roller having at least one coating layer formed thereon, wherein the roller outer diameter difference fluctuation of the charging member is equal to or less than the roller crown amount of the charging member, and the surface of the charging member is A process cartridge characterized in that the static friction coefficient is 1.0 or less and the surface roughness (Rz) of the charging member is 5 μm or less.

(3) The image forming apparatus and the process cartridge according to (1) and (2), wherein the developing unit has a unit for collecting a toner remaining on the photoconductor after transfer.

(4) A toner used in the image forming apparatus and the process cartridge according to the above (1) and (2), wherein the toner contains toner particles and inorganic fine powder. .

(5) A charging member used in the image forming apparatus and the process cartridge described in (1) and (2) above, wherein the charging member comprises a conductive support and one or more coating layers formed thereon. The charging member has a roller outer diameter difference runout of not more than a roller crown amount of the charging member, and a static friction coefficient of a surface of the charging member is 1.0 or less, and A charging member having a surface roughness (Rz) of 5 μm or less.

(6) The toner has an average primary particle diameter of 4
A toner comprising an inorganic fine powder having a particle size of from 500 to 500 nm.

(7) The toner is characterized in that it contains an inorganic fine powder whose surface has been subjected to a hydrophobic treatment.

(8) The toner particles of the toner are toner particles produced by a polymerization method, and are spherical.

(9) The coating layer of the charging member is a charging member having a laminated structure in which at least an elastic layer and a surface layer are formed in this order.

(10) The roller hardness of the charging member is 30
帯 電 75 °.

That is, by using the image forming apparatus, the process cartridge, the toner and the charging member having the configuration as described in (1) to (10) above, the toner particles and the external additive adhere to the charging roller. Thus, it is possible to provide an image forming apparatus which does not cause an image defect and has excellent durability. Hereinafter, embodiments of an image forming apparatus, a process cartridge, a toner, and a charging member of the present invention for achieving the object of the present invention will be described in detail.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a schematic configuration of an image forming apparatus and a process cartridge according to the present invention will be described. (1) Image Forming Apparatus and Process Cartridge FIG. 1 is a schematic configuration diagram showing an example of the image forming apparatus of the present invention. The image forming apparatus of the present example uses a transfer type electrophotographic,
It is an apparatus of a reversal development system and a simultaneous development cleaning system (cleanerless).

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (photosensitive member) as an image carrier. The photoconductor 1 is driven to rotate at a predetermined peripheral speed (process speed) clockwise as indicated by an arrow in the figure. As the photoreceptor 1, a photoreceptor having a known configuration can be used. Examples of such a photoreceptor include a roll-shaped conductive base and a photosensitive base containing an inorganic or organic photosensitive material on the base. And a photoreceptor having at least a layer. Further, the photoconductor 1 may further have a charge injection layer for charging the photoconductor surface to a predetermined polarity and potential.

Reference numeral 2 denotes a charging roller (conductive roller) as a charging member. Charging means is constituted by the charging roller 2 and a charging bias application power source S1 for applying a charging bias to the charging roller 2. The charging roller 2 includes the photosensitive member 1
Are contacted with a predetermined pressing force, and in this example, the photosensitive member 1 is driven to rotate in the forward direction. This charging roller 2
A predetermined DC voltage (-1300 V in this example) is applied from the charging bias application power supply S1 to the surface of the photoconductor 1 to a predetermined polarity potential (dark-area potential -700 V in this example). D) of the contact charging method
It is charged by a C charging method. The configuration of the charging roller 2 will be described later in detail.

Reference numeral 3 denotes exposure means. A known means can be used as the exposure means 3, and a laser beam scanner or the like can be preferably exemplified. By performing image exposure corresponding to target image information on the charged surface of the photoreceptor 1 by the exposing means 3, the potential of the exposed light portion of the charged surface of the photoreceptor (in this example, the light portion potential is -350 V).
Is selectively reduced (attenuated), and an electrostatic latent image is formed on the photoconductor 1.

Reference numeral 4 denotes reversal developing means. As the developing unit 4, a known unit can be used. For example, the developing unit 4 in the present embodiment is a toner carrier 4a that is disposed at an opening of a developing container that stores toner and carries and transports the toner.
A stirring member 4b for stirring the stored toner;
And a toner regulating member 4c for regulating the amount of toner (toner layer thickness) of the toner carried on the toner carrier 4a. The developing means 4 applies a toner (negative toner) charged to the exposed portion of the electrostatic latent image on the surface of the photoconductor 1 to the same polarity as the charging polarity of the photoconductor 1 (in this example, the developing bias is −350 V). The electrostatic latent image is visualized as a toner image by being selectively attached. The toner will be described later in detail.

Reference numeral 5 denotes a transfer roller as transfer means.
As the transfer roller 5, known means can be used, and examples thereof include a transfer roller formed by coating a conductive core with an elastic resin layer adjusted to have a medium resistance. The transfer roller 5 contacts the photosensitive member 1 with a predetermined pressing force to form a transfer nip portion, and rotates in a forward direction with rotation of the photosensitive member 1 at substantially the same peripheral speed as the rotational speed of the photosensitive member 1. . Further, a transfer voltage having a polarity opposite to the charging characteristic of the toner is applied from the transfer bias applying power source S2. The transfer material P is fed to the transfer nip from a paper feed mechanism (not shown) at a predetermined timing, and the back surface of the transfer material P is opposite to the charge polarity of the toner by the transfer roller 5 to which the transfer voltage is applied. By being charged to the polarity, the toner image on the surface of the photoconductor 1 is electrostatically transferred to the surface of the transfer material P at the transfer nip portion.

The transfer material P to which the toner image has been transferred at the transfer nip portion is separated from the photoreceptor surface, introduced into a toner image fixing means (not shown), and fixed as a toner image to be output as an image-formed product. You. In the case of the double-sided image forming mode or the multiple image forming mode, this image-formed product is introduced into a recirculating transport mechanism (not shown) and is again introduced into the transfer nip portion.

Residues on the photoreceptor 1 such as transfer residual toner are charged by the charging roller 2 to the same polarity as the photoreceptor charging polarity. The transfer residual toner reaches the developing unit 4 through the exposure unit, and is electrically connected to the developing unit 4 by the back contrast (the potential difference between the image portion and the non-image portion in the electrostatic latent image).
Collected in the inside, and simultaneous development cleaning (cleanerless)
To achieve.

In the image forming apparatus of this embodiment, two or more different means are integrally supported by a support member such as a resin molded body, and can be detachably attached to the image forming apparatus main body with this integrated structure. May be an apparatus having a process cartridge configured as described above. The two or more different means may be, for example, a combination of the photoconductor 1 and the developing means 4, a combination of the photoconductor 1 and the charging roller 2 and the developing means 4, and a combination of the charging roller 2 and the developing means 4. It is preferable that the selection be made in consideration of the life of the means and members, the degree of toner consumption, and the like.

(2) Toner The toner that can be used in the image forming apparatus of the present invention is a toner containing toner particles and inorganic fine powder, and the shape of the toner particles is preferably spherical. The shape of the toner particles can be defined by shape factors SF-1 and SF-2. That is, the toner particles have a shape factor SF-1 of 100 to 150 and a shape factor SF
-2 is preferably from 100 to 140.

The shape factor SF-1 indicates the degree of roundness of the toner particles, and the shape coefficient SF-2 indicates the degree of unevenness of the toner particles. When SF-1 is 100, the toner is completely spherical, and as the value increases therefrom, the toner gradually becomes irregular. As the value of SF-2 increases from 100, the toner particle surface becomes uneven. If these coefficients are larger than the above ranges, the toner particles will not be spherical, and the unevenness on the surface will be remarkable, and the uniformity of triboelectric charging of the toner will be impaired.

The shape factors SF-1 and SF-2 are randomly sampled, for example, using a FE-SEM (S-800) manufactured by Hitachi, Ltd., to sample 100 toner particle images magnified 500 times, and via an interface. The image information is obtained by using, for example, an image analyzer (Luzex II) manufactured by Nireco.
It can be measured by introducing into I) and performing analysis. The value calculated from the following equation is defined as shape factor SF-1.

## EQU1 ## SF-1 = (MXLNG) ² / AREA × (π
/ 4) × 100 where MXLNG indicates the absolute maximum length of the toner particles and AR
EA indicates the projected area of the toner particles.

Further, the shape factor SF-2 refers to a value obtained from the following equation.

## EQU2 ## SF-2 = (PERI) ² / AREA × (1 /
4π) × 100 In the formula, PERI indicates the circumference of the toner particles, and AREA indicates the projected area of the toner particles.

As the toner particle diameter, the weight average particle diameter is 3
Toner particles having a small particle size of 10 to 10 μm are preferred. If the weight average particle size is less than 3 μm, the transfer residual toner on the photoreceptor increases due to a decrease in transfer efficiency, and it tends to be difficult to suppress the abrasion of the photoreceptor and the fusion of the toner in the contact charging step. Furthermore, in addition to an increase in the surface area of the entire toner, the fluidity and agitation properties of the powder decrease, and it becomes difficult to uniformly charge the individual toner particles, so that fog occurs and transferability deteriorates. This is not preferable for the magnetic toner of the present invention because it tends to cause non-uniform unevenness of an image other than abrasion and fusion. On the other hand, if the weight average particle size is larger than 10 μm, characters and line images are liable to be scattered, and it is difficult to obtain a high-resolution image.

The weight average particle diameter of the toner particles is measured by using a Coulter counter TA-II or
Use Coulter Multimizer II (manufactured by Coulter Inc.). The weight average particle diameter obtained by this measuring device is defined as the toner particle diameter of the toner of the present invention.

The toner of the present invention is not particularly limited as long as it satisfies the above conditions, but usually, a non-magnetic one-component developer is preferably used. As the toner particles of the non-magnetic one-component developer, a pulverization method can be used as a known technique for the generation thereof, but it is preferable to use toner particles generated by a polymerization method. In particular, since the toner particles formed by polymerizing the surface layer portion of the toner particles are generated by polymerizing the monomer composition in a dispersion medium, the surface of the toner particles should have a substantially smooth spherical surface. Can be.

The non-magnetic one-component toner particles used in the present invention can be obtained by subjecting a monomer composition containing at least a polymerizable monomer, a colorant and a release agent to suspension polymerization in an aqueous medium. it can.

Examples of the polymerizable monomer usable in the present invention include styrene-based monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene and p-ethylstyrene. Body, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate,
Acrylates such as n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate and phenyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate; Isobutyl methacrylate, n-propyl methacrylate, n-methacrylate
Monomers such as octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate, and other monomers such as acrylonitrile, methacrylonitrile, and acrylamide. No. These monomers can be used alone or as a mixture. Among the above-mentioned monomers, it is preferable to use styrene or a styrene derivative alone or in combination with another monomer from the viewpoint of the developing characteristics and durability of the toner.

In the present invention, it is preferable to add a polymer having a polar group and a copolymer as an additive to the monomer system for polymerization. Since the polar polymer and the copolymer gather at the surface layer of the toner particles, the polar polymer and the copolymer form a kind of shell. By conducting polymerization so as to contribute to improvement in fixing characteristics with a relatively low molecular weight, it is possible to obtain a toner that satisfies conflicting requirements of fixing properties and anti-blocking properties. The polar polymer and polar copolymer that can be used in the present invention are exemplified below.

Polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, or copolymers with styrene and unsaturated carboxylic esters, nitrile monomers such as acrylonitrile,
Polymers such as halogen-containing monomers such as vinyl chloride, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, other unsaturated dibasic acids, unsaturated dibasic acid anhydrides, nitro monomers, and styrene monomers. And a copolymer with a monomer and the like, polyester, epoxy resin and the like. It is particularly preferable to add a polyester resin from the viewpoint of maintaining the core / shell structure. The amount of the polar polymer and the polar copolymer is 0.1 to 10 parts by weight of the polymerizable monomer.
Part by weight, more preferably 0.5 to 5 parts by weight is preferred.
If the amount of the polymer or the like is too small than the above range,
The effects described above may not be sufficiently exhibited. On the other hand, if it is larger than the above-mentioned range, the fixing property is deteriorated, and the problem that the frictional charge amount of the toner particles is reduced under high humidity is caused.

As the colorant used in the present invention, known colorants can be used, for example, carbon black, C.I.
I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Modant Red 30, C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I.
I. Acid Blue 9, C.I. I. Acid blue 15,
C. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Modant Blue 7, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I.
I. Dyes such as Basic Green 6, graphite, cadmium yellow, mineral fast yellow, navel yellow, naphthol yellow S, Hanza yellow G, permanent yellow NCG, tartrazine lake, molybdenum orange, permanent orange GTR, benzidine orange G, cadmium red, Permanent red 4
R, Watching Red Calcium Salt, Brilliant Carmine 3B, Fast Violet B, Methyl Violet Lake, Navy Blue, Cobalt Blue, Alkaline Blue Lake Victoria Blue Lake, Quinacridone, Rhodamine Lake, Phthalocyanine Blue, Fast Sky Blue, Pigment Green B, Malachite Green Lake And final yellow green.

In the present invention, it is preferable to generate toner particles using a polymerization method. However, it is necessary to pay attention to the polymerization inhibitory property and the water phase transfer property of the colorant. For example, a hydrophobic treatment with a substance having no polymerization inhibition may be performed. In particular, many dyes and carbon black have polymerization inhibitory properties,
Care must be taken when using. As a preferable method of surface-treating the dye system, a method of previously polymerizing a polymerizable monomer in the presence of these dyes is mentioned, and the obtained colored polymer is added to the monomer system.

The carbon black may be treated with a substance which reacts with the surface functional group of the carbon black, such as polyorganosiloxane, in addition to the same treatment as the above dye. When a color toner is used, it is desirable to select and use a disazo yellow dye, a quinacridone magenta pigment and a phthalocyanine cyan pigment.

The release agent used in the present invention includes paraffinic and polyolefinic waxes, modified products thereof, for example, oxides and grafted products, higher fatty acids and their metal salts, amide waxes, ester waxes. Having, for example, a tertiary and quaternary carbon, a polyfunctional polyester compound obtained from a difunctional or higher alcohol compound or a carboxylic acid compound, and having at least one of primary and secondary carbons; Examples include a polyfunctional polyester compound obtained from a bifunctional or higher alcohol compound or a carboxylic acid compound, and a monofunctional ester compound having at least one of tertiary and quaternary carbons.

In the present invention, it is desirable to add a charge control agent to the toner material in order to control the chargeability of the toner. As these charge control agents, those having little polymerization inhibition and water phase transfer among known ones are used. For example, as positive charge control agents, nigrosine dye, triphenylmethane dye, quaternary ammonium Examples include salts, guanidine derivatives, imidazole derivatives, amine-based and polyamine-based compounds. Examples of the negative charge control agent include a metal-containing salicylic acid-based compound, a metal-containing monoazo-based dye compound, a urea derivative, a styrene-acrylic acid copolymer, and a styrene-methacrylic acid copolymer. The charge control agent is preferably added in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polymerizable monomer. If the added amount of the charge control agent is smaller than the above range, the above-mentioned effects may not be sufficiently exerted. On the other hand, if it is larger than the above range, the difference in the amount of triboelectric charge of the toner particles between high humidity and low humidity increases, and the charge control agent detaches from the surface of the toner particles and easily contaminates the toner supply member. Occurs.

The polymerization initiator used in the present invention includes:
Any suitable polymerization initiator, for example, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1- Carbonitrile), 2,2′-azobis-4
Azo or diazo polymerization initiators such as -methoxy-2,4-dimethylvaleronitrile and azobisisobutyronitrile, and benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide And peroxide-based polymerization initiators such as lauroyl peroxide. These polymerization initiators are used in an amount of 0.5 to 2 based on 100 parts by weight of the polymerizable monomer.
The addition amount of 0 parts by weight is preferable, and they may be used alone or in combination. If the amount of the polymerization initiator is out of the above range, the polymerization of the polymerizable monomer may be adversely affected, and the physical properties of the toner particles may be adversely affected.

In the present invention, a known crosslinking agent, chain transfer agent or the like may be added in order to control the molecular weight. A preferable addition amount is 0 to 100 parts by weight of the polymerizable monomer. 0.0001 to 15 parts by weight. The amount of the cross-linking agent or the like varies depending on the type or the like used, but if it is smaller than the above range, its effect may not be sufficiently exerted.If it is larger than the above range, physical properties of the toner particles may be adversely affected. May have an effect.

The toner of the present invention contains an inorganic fine powder as an external additive for the purpose of improving the fluidity of the toner and imparting various toner characteristics such as uniform charging of the toner particles. From the viewpoint of the durability of the toner when the inorganic fine powder is added, the inorganic fine powder preferably has a particle size of 1/5 or less of the volume average system of the toner particles. In particular, the average primary particle diameter is 4 to
Preferably it is 500 nm. When the average primary particle diameter of the inorganic fine powder is larger than 500 nm, or when the inorganic fine powder is not added, the transfer residual toner easily adheres to the charging member, causing an image defect and a good toner. Cannot be obtained, and the charging of the toner particles is not uniform, which may cause problems such as an increase in fog, a decrease in image density, and toner scattering. On the other hand, when the average primary particle size of the inorganic fine powder is smaller than 4 nm, the cohesiveness of the inorganic fine powder is increased, and the aggregates having a large particle size distribution having strong cohesiveness that is hard to be disaggregated by the disintegration treatment instead of the primary particles. , And image defects such as development of agglomerates and damage to the photoreceptor or toner carrier are likely to occur.

The average primary particle diameter of the inorganic fine powder used in the present invention can be determined by observing the surface of the toner particles with a scanning electron microscope and finding the primary particles of the inorganic fine powder adhered or separated on the toner particle surface. Measure 100 or more diameters,
It can be obtained by calculating the average diameter.

As the external additive for imparting properties, for example, the following can be used. 1) Fluidity-imparting agents: metal oxides (such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide and chromium oxide), nitrides (such as silicon nitride), carbides (such as silicon carbide) and metal salts (calcium sulfate, Barium sulfate and calcium carbonate). 2) Abrasives: metal oxides (such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide and chromium oxide), nitrides (such as silicon nitride), carbides (such as silicon carbide) and metal salts (calcium sulfate, barium sulfate) And calcium carbonate). 3) Lubricants: fluorinated resin powders (such as vinylidene fluoride and polytetrafluoroethylene), and fatty acid metal salts (such as zinc stearate and calcium stearate). 4) Charge controllable particles: metal oxides (such as tin oxide, titanium oxide, zinc oxide, silicon oxide and aluminum oxide) and carbon black. These external additives are toner particles 1
It can be said that 0.1 to 10 parts by weight is used per 100 parts by weight, and preferably 0.1 to 5 parts by weight. If the amount of the external additive (inorganic fine powder) is smaller than the above range, the effect may not be sufficiently exhibited,
If it is larger than the above range, the fixability may be deteriorated. These external additives may be used alone or in combination of two or more.

Further, it is more preferable to use those external additives which have been subjected to a hydrophobic treatment. This is because, in a high-temperature and high-humidity environment, when the added inorganic fine powder absorbs moisture, the charge amount of the toner particles is significantly reduced, and the toner is easily scattered. As treatment agents for the hydrophobizing treatment, silicone varnish, various modified silicone varnishes,
Examples include silicone oils, various modified silicone oils, silane compounds, silane coupling agents, and other treating agents such as organic silicon compounds and organic titanium compounds. These treating agents may be used alone or in combination.

Inorganic fine powders are generally hydrophilic and excellent in dispersibility in water, and are not easily affected by the material of the treating agent, such as when a highly viscous treating agent is used. For example, the surface treatment is preferably performed by hydrolysis of the coupling agent in an aqueous medium.

Any suitable stabilizer can be used in the dispersion medium used in the present invention. For example, as an inorganic compound, calcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite,
Examples include silica and alumina. Further, as an organic compound, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, polyacrylic acid, polyacrylate, starch and the like can be used by dispersing them in an aqueous phase. These stabilizers are preferably used in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer. If the amount of the stabilizer is too small, the effect may not be sufficiently exhibited. If the amount is too large, the dispersion of the polymerizable monomer composition may be adversely affected.

When an inorganic compound is used among these stabilizers, a commercially available one may be used as it is, but in order to obtain fine particles, the inorganic compound may be formed in a dispersion medium. good. For example, in the case of calcium phosphate, an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride are preferably mixed under high stirring.

In order to finely disperse these stabilizers, 0.001 to 100 parts by weight of the polymerizable monomer is used.
0.1 parts by weight of a surfactant may be used. this is,
It is for promoting the initial action of the dispersion stabilizer, and specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, and stearin. And potassium oleate. If the amount of these surfactants is too small, the effect may not be sufficiently exhibited. If the amount is too large, the surface condition of the toner particles may be deteriorated.

The toner particles used in the present invention can be specifically manufactured by the following method. Add a release agent, a colorant, a charge control agent, a polymerization initiator and other additives to the monomer, and disperse the monomer composition uniformly dissolved or dispersed by a homogenizer, an ultrasonic disperser or the like. It is dispersed in an aqueous phase containing a stabilizer using a conventional stirrer, homomixer, homogenizer or the like. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer diameter.

Preferably, the granulation is carried out by adjusting the stirring speed and time so that the droplets of the monomer composition have the desired size of the toner particles. After that, by the action of the dispersion stabilizer, stirring may be performed to such an extent that the particle state is maintained and the particles are prevented from settling. The polymerization is performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. Further, the temperature may be raised in the latter half of the polymerization reaction, and further, the aqueous medium may be partially distilled off at the latter half of the reaction or at the end of the reaction to remove unreacted polymerizable monomers, by-products, and the like. . After completion of the reaction, the pH is adjusted, the dispersion stabilizer is dissolved, and the generated toner particles are collected by filtration, collected, and dried.

In the case of producing toner particles by a pulverizing method, a binder resin containing various desired materials is pulverized,
Using a hot water bath method of dispersing the obtained toner particles in hot water, a method of passing the toner particles through a hot air stream, a method of applying a mechanical impact force to the toner particles by a force such as a compressive force or a frictional force, or the like, It is preferable to adjust the shape and surface condition.

In the above-described method, the obtained toner particles are classified using a multi-segment classifier or the like, whereby a group of toner particles having a uniform particle size can be obtained. Further, by appropriately mixing the classified toner particles of each class, it is possible to produce a toner having a desired particle distribution.

(3) Charging Member FIGS. 2 to 4 show examples of the charging member of the present invention (hereinafter also referred to as “charging roller”). For example, the charging member is in the form of a roller as shown in FIG. 2, and includes a conductive support 2a, an elastic layer 2b formed on the entire outer periphery thereof, and a surface layer 2d formed on the outer periphery thereof. Another configuration of the charging member according to the present invention is shown in FIGS. As shown in FIG. 3, the charging member may have a three-layer structure in which a resistance layer 2c is provided between an elastic layer 2b and a surface layer 2d, or as shown in FIG. 4, the resistance layer 2c and the surface layer 2d. Between the second resistance layer 2
e may be a four-layer structure, or a structure in which a resistance layer is further provided and four or more layers are formed on the conductive support 2a.

The conductive support 2a used in the present invention comprises:
A round bar of a metal material such as iron, copper, stainless steel, aluminum, and nickel can be used. Further, these metal surfaces may be plated for the purpose of imparting scratch resistance, but it is necessary that the conductivity is not impaired.

The elastic layer 2b used in the present invention has an appropriate conductivity and elasticity in order to supply power to the photosensitive member 1 as a member to be charged and to ensure good uniform adhesion of the charging roller 2 to the photosensitive member 1. And

In order to ensure uniform adhesion between the charging roller 2 and the photoreceptor 1, the charging roller 2 is formed by polishing the elastic layer 2b so that the center portion is thickest and the shape becomes thinner toward both ends, that is, a so-called shape. Preferably, it is formed in a crown shape. In a generally used charging roller, a predetermined pressing force is applied to both ends of the conductive support 2a and comes into contact with the photoreceptor 1, so that the pressing force at the center is small, and the pressing force at the both ends is larger. If the straightness of the charging roller is sufficient, there is no problem. However, if the straightness is not sufficient, density unevenness may occur in images corresponding to the center and both ends. The crown shape is formed to prevent this.

As the material of the elastic layer 2b used in the present invention, any material may be used as long as it is an elastomer such as a synthetic rubber and a thermoplastic elastomer. For example, as synthetic rubber, natural rubber (vulcanization treatment, etc.), EP
DM, SBR, silicone rubber, urethane rubber, IR,
BR, NBR, CR and the like. Examples of the thermoplastic elastomer include a polyolefin-based thermoplastic elastomer, a urethane-based thermoplastic elastomer, a polystyrene-based thermoplastic elastomer, a fluororubber-based thermoplastic elastomer, a polyester-based thermoplastic elastomer, a polyamide-based thermoplastic elastomer, a polybutadiene-based thermoplastic elastomer, and ethylene. Examples thereof include a vinyl acetate-based thermoplastic elastomer, a polyvinyl chloride-based thermoplastic elastomer, and a chlorinated polyethylene-based thermoplastic elastomer. These materials may be used alone or as a mixture of two or more, and may be a copolymer.

A foam obtained by foaming these elastic materials may be used as the elastic material. Preferably, in order to secure a nip between the charging roller and the photoconductor, it is preferable to use a synthetic rubber material for the elastic layer material. Also,
In the DC charging system, it is more preferable to use a polar rubber among the above synthetic rubber materials. An example of the polar rubber is epichlorohydrin rubber.

The conductivity of the elastic layer 2b can be reduced to less than 10 ⁸ Ω · cm by appropriately adding a conductive agent such as carbon black, a conductive metal oxide, an alkali metal salt and an ammonium salt to the above elastic material. Preferably, it is adjusted. If the conductivity of the elastic layer 2b is 10 ⁸ Ω · cm or more, the charging ability of the charging roller is lowered, and it becomes impossible to satisfy the charging uniformity for uniformly charging the charged member. The elasticity and hardness of the elastic layer 2b are adjusted by adding a softening oil, a plasticizer, and the like, and firing the elastic material.

The material constituting the surface layer 2d used in the present invention may be any material as long as it is a resin or an elastomer. Examples of the resin include fluororesin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, styrene-ethylene / butylene-olefin copolymer (SEBC), olefin-
Ethylene / butylene-olefin copolymer (CEBC)
And the like. Further, the elastomer is the same as that described in the elastic layer material.

The surface layer 2d constitutes the surface of the charging member,
A material that contaminates the photoreceptor because it comes into contact with the photoreceptor to be charged is not preferable. It can be said that those having good surface release properties are preferable. Therefore, it can be said that it is preferable to use a resin as the surface layer material.

It is preferable to add various conductive agents to the surface layer 2d to adjust the electric resistance to a desired value. As a conductive material of the surface layer, carbon black, tin oxide, titanium oxide, zinc oxide, barium sulfate, copper, aluminum,
Nickel and the like can be mentioned. These conductive agents may be subjected to a surface (hydrophobic) treatment, and examples of the surface treatment include a coupling treatment and a fatty acid treatment. Typical examples of the coupling treatment include those using a silane coupling agent and a titanate-based coupling agent, and examples of the fatty acid treatment include those using an acid such as stearic acid. By performing these treatments, the dispersibility of the conductive agent in the surface layer material can be improved. Therefore, the conductive agent is
It is preferable to use a surface-treated one. More preferably, tin oxide subjected to titanate coupling treatment is used. Further, in order to obtain a desired electric resistance, two or more of these various conductive agents may be used in combination.

The electric resistance of the surface layer 2d is preferably adjusted to be higher than the electric resistance of the elastic layer and not more than 10 ¹⁵ Ω · cm. If the electric resistance of the surface layer 2d is smaller than that of the elastic layer, it is not possible to prevent leakage due to pinholes and scratches on the surface of the member to be charged, and if it is larger than 10 ¹⁵ Ω · cm, the charging ability of the charging roller And the charge uniformity may not be satisfied.

For the purpose of preventing bleeding out of the surface of the charging member such as a softening oil or a plasticizer contained in the elastic layer, a resistance layer 2c is provided at a position in contact with the elastic layer 2b. Can be provided.

The same material as that used for the elastic layer 2b can be used as the material forming the resistance layer 2c. Further, the resistance layer 2c preferably has conductivity or semi-conductivity. As the conductive material, various conductive agents listed for the surface layer 2d can be used. In this case, in order to obtain a desired electric resistance, two or more of the above-mentioned various conductive agents may be used in combination.

It is preferable that the electric resistance of the resistance layer 2c is adjusted to be equal to or less than the electric resistance of the surface layer and equal to or more than the electric resistance of the elastic layer. If the ratio is out of this range, the charge uniformity may not be satisfied.

For the elastic layer 2b, the surface layer 2d, and the resistance layer 2c, materials having other functions can be appropriately used in addition to the various materials described above. Examples of such other materials include an antiaging agent such as 2-mercaptobenzimidazole and a lubricant represented by stearic acid and zinc stearate in the elastic layer 2b.

The conductivity (electrical resistance) of the elastic layer 2b, the surface layer 2d and the resistance layer 2c can be measured, for example, by using a resistance measuring device (Hiresta-U, an insulation resistance meter manufactured by Mitsubishi Chemical Corporation).
P). More specifically, in the elastic layer 2b, the elastic layer material itself is formed into a 2 mm-thick film.
Conductivity is measured by applying a voltage of 10 V for 1 minute in an environment of 55 ° C. and 55%. In the surface layer 2d and the resistance layer 2c, the same binder resin as that in which each layer was formed was made into a paint, the clear paint was coated on an aluminum sheet, and the conductivity of each layer was measured under the above conditions. I do.

The method of forming the elastic layer 2b, the surface layer 2d, and the resistance layer 2c is not particularly limited as long as it is a method suitable for forming each layer to a suitable thickness. It can be manufactured by using the method described above. The production of these layers may be performed, for example, by bonding or coating a sheet-like or tube-like layer formed in advance to a predetermined thickness, or conventionally known such as electrostatic spraying and dipping coating. It may be carried out by a method of construction or according to it. Further, a method may be used in which a layer is roughly formed by extrusion molding and then the shape is adjusted by polishing or the like, or a method in which a material is cured and molded into a predetermined shape in a mold may be used.

The thickness of the elastic layer 2b, the surface layer 2d and the resistance layer 2c is not particularly limited as long as the function of each layer is not impaired. It is preferred that When the thickness of the elastic layer is 0.5 mm or less, the elastic layer cannot maintain appropriate elasticity, and the contact with the member to be charged becomes inappropriate, so that the charging uniformity cannot be satisfied. However, this is not preferable.

The thickness of the surface layer or the resistance layer is preferably 1 μm to 1000 μm. If the thickness of the surface layer is smaller than the above range, unevenness of the layer thickness is likely to occur, and the unevenness of the elastic layer will appear on the surface of the charging roller as it is. As a result, the charging uniformity cannot be satisfied, and since the surface of the charging roller is undesirably formed, the toner particles and external additives tend to adhere to the roller surface, which is not preferable.
On the other hand, if it is larger than the above range, the appropriate elasticity held by the elastic layer is lost, and the contact with the member to be charged becomes improper, so that the charging uniformity cannot be satisfied. Is not preferred.

The thicknesses of the elastic layer 2b, the surface layer 2d and the resistance layer 2c can be determined by observing the cross section of the layer with an optical microscope.
It is determined by actually measuring the layer thickness. Specifically, the roller is cut with a cutter knife or the like, and the cut portion is observed with an optical microscope to measure the thickness of each layer.

Next, the features of the charging member of the present invention will be described. As a result of intensive studies by the present inventors, the molding accuracy of the charging member, the coefficient of static friction and surface roughness on the surface of the charging member, and further the toner particle shape and the like, show the adhesion of the toner particles and external additives to the charging member. It became clear that there was a causal relationship.

Although the charging member and the photoreceptor are rotating while contacting with each other, when the molding accuracy of the charging member is poor, that is, when the difference in outer diameter is large, a gap is formed between the charging member and the photoreceptor. Come. Furthermore, the gap distance also varies.
In this case, the toner particles and the external additive remaining on the photoreceptor easily enter the gap, and adhere to the charging roller in a non-uniform manner. Therefore, the roller surface becomes mottled, resulting in an image defect. Investigations by the present inventors have revealed that if the roller outer diameter difference runout is equal to or less than the roller crown amount, and preferably equal to or less than の of the roller crown amount, no unevenness in adhesion occurs.

The measurement of the roller outer diameter difference runout of the charging member in the present invention is performed by using a high-precision laser measuring machine L manufactured by Mitutoyo Corporation.
Performed using SM-430v. The outer diameter is measured by this measuring instrument, and the difference between the maximum outer diameter value and the minimum outer diameter value is defined as the outer diameter difference deflection. Further, this measurement is performed for each of five points on the roller, and the average value is defined as the roller outer diameter difference runout.

Further, the measurement of the roller crown amount of the charging member in the present invention is also performed using the above-mentioned high precision laser measuring machine LSM-430v manufactured by Mitutoyo Corporation. With this measuring device, the outer diameter is measured at the center of the roller and at a position of 90 mm from the center to the end, and the difference between the outer diameter of the center and the average value of the outer diameter at each position of 90 mm toward both ends is determined by the roller. The crown amount. For example, in the case of a charging member having a roller length of 250 mm, 35 mm, 125 mm, 21 mm
The outer diameter is measured at three points of 5 mm. At that time, 35m
Assuming that the outer diameter at the m position is A (mm), the outer diameter at the 125 mm position is B (mm), and the outer diameter at the 215 mm position is C (mm), the roller crown amount (μm) is obtained by the following equation.

## EQU3 ## Roller crown amount (μm) = ｛B− (A + C)
/ 2｝ × 1000

Conventionally, the crown shape of a member such as a charging roller elastic layer is formed by a polishing method called a traverse method. In this method, a roller is formed into a crown shape by moving a short grindstone according to the roller. However, if it is attempted to form the outer diameter difference runout accuracy with a roller crown amount or less with this method, a very long time is required. On the other hand, in the present invention, it is preferable to employ a wide polishing method.

According to the wide polishing method employed in the present invention, a grindstone having a literally wide width, that is, a grindstone having a width approximately equal to the length of the charging roller is used, and the roller can be polished in a short time by pressing the grindstone once. It is a method. According to this method, it is possible to achieve the goal of reducing the outer diameter difference run-out of the roller to the roller crown amount or less, preferably １ ／ or less of the roller crown amount in a short time.

In order to increase the accuracy of the deviation of the outer diameter during the polishing of the roller, it can be said that the higher the hardness of the roller, the better. For example, when the roller hardness is low, the roller may be displaced from the grindstone and accuracy may not be improved. However, if the roller has an excessively high hardness, the nip between the charging roller and the photoconductor cannot be sufficiently secured, and charging failure may occur. As a result of the study by the present inventors, the preferable roller hardness of the charging roller is 30 to 7
It was found that the range was 5 °.

The measurement of the roller hardness of the charging roller is performed using an Asker-C rubber hardness meter manufactured by Kobunshi Keiki Co., Ltd. More specifically, the rubber hardness at any five points of the charging roller is measured by the hardness meter, and the average value of the five points is defined as the roller hardness.

In the charging member of the present invention, when the static friction coefficient on the surface of the charging roller is large, it is considered that toner particles and external additives easily adhere to the surface of the roller and are hardly separated from the surface. Examinations by the present inventors have revealed that it is preferable that the coefficient of static friction of the roller is 1.0 or less in order not to cause image defects. In order to achieve this characteristic, it is preferable to select a surface layer material having a static friction coefficient of 0.50 or less (hereinafter, this material is also referred to as “binder resin”). Hereinafter, the coefficient of static friction of the surface of the charging member and mu _S, the coefficient of static friction of the binder resin of the surface layer as mu _SB, illustrating the measurement of the static friction coefficient.

In the present invention, the static friction coefficient μ _SB of the binder resin in the selection of the material of the surface layer was measured by forming the binder resin as a coating film on an aluminum sheet to obtain a sample sheet.
Static friction coefficient measuring device: Measured using HEIDON Tribogear Muse TYPE: 941 (manufactured by Shinto Kagaku Co., Ltd.) to obtain a static friction coefficient μ _{SB of the} resin material binding to the surface layer of the charging member.

A material having a static friction coefficient μ _SB of 0.50 or less obtained by this measuring method contains a conductive agent and other additives to form a surface layer of a charging member. Further, the material of the charging member is designed so that the surface of the charging member has a static friction coefficient μ _{S of} 1.0 or less.

[0100] The method of measuring static friction coefficient mu _S of the charging member surface in the present invention is shown in FIG. This measurement method is a method suitable for a case where the object to be measured has a roller shape, and is a method according to the Euler belt type. According to this method, a belt (with a thickness of 20 μm) that contacts a charging member as a measurement object at a predetermined angle (で).
m, a width of 30 mm, and a length of 180 mm), one end is connected to the measurement unit (load meter), and the other end is connected to the weight W.
In this state, when the charging member is rotated at a predetermined direction and speed, the force measured by the measuring unit is F (g), and the weight is W.
(G), the coefficient of friction (μ) is obtained by the following equation.

Μ = (1 / Θ) ln (F / W)

FIG. 6 shows an example of a chart obtained by this measuring method. In addition, in this example, it is a measurement result when the charging member is rotated for 60 seconds. Here, it can be seen that the value of the load immediately after rotating the charging member is the force required to start rotation, and the value of the load thereafter is the force required to continue rotation. The force at the start of rotation (that is, at the time of t = 0 seconds) can be referred to as static friction force, and the force at any time of 0 <t (seconds) ≦ 60 can be referred to as dynamic friction force at any time. Thus, the static friction coefficient mu _S of the charging member surface may be obtained by the following equation.

Equation 5] _{μ S = (1 / Θ)} ln (F <t = 0> / W) In the drawing, A and B are the upper and lower limit of the dynamic frictional force.

In this measurement method, the surface of the belt (the surface that comes into contact with the charging member) is made of a predetermined material (for example, the outermost layer of the photoreceptor, a material coated with toner by an appropriate means, or a standard material such as stainless steel). Thereby, the coefficient of friction for various substances can be obtained. That is,
It is more preferable to match the material of the contact surface, the rotation speed, the load, etc. with the process conditions of the actual machine.However, the measurement of the friction coefficient between the charging member and the photoconductor and the measurement of the friction coefficient between the charging member and stainless steel are performed. As a result of the study, it was found that the friction coefficient for stainless steel may be used. That is,
The coefficient of friction between the charging member and the photosensitive member is approximately represented by K × the coefficient of friction between the charging member and stainless steel.

Here, K is a value determined by the material and condition of the surface of the photoreceptor, and is a substantially constant value if the material and surface condition of the photoreceptor are the same, but changes if they are slightly different. Resulting in. Therefore, it is desirable that the material types, their compounding ratios, manufacturing conditions, surface physical properties, and the like match as much as possible with the actual system, but this requires great complexity and, as described above, the charging member and the photoconductor. And the friction coefficient between the charging member and the stainless steel tend to have regularity. Therefore, in the present invention, for the sake of simplicity, the friction coefficient is made of stainless steel (the ten-point average surface roughness Rz is 5 μm or less) and a rotation speed of 100
The static friction coefficient of the charging member surface was measured under the conditions of rpm and load of 50 g.

Further, as a result of studies by the present inventors, the charging member of the present invention has a ten-point average surface roughness Rz of 5 μm or less in the JISB0601 surface roughness standard.
It has been found to be important in the present invention. This is because if there are irregularities on the surface of the charging roller, the toner particles and the external additive enter there, causing contamination of the charging member surface. Roughly speaking, it is sufficient that the surface roughness is not more than the particle size of the toner particles and the external additive.

When the charging roller of the present invention is used,
If the surface of the charging roller is rough, uneven charging on the surface may cause subtle charging unevenness, resulting in image defects. Alternatively, the photoconductor surface may be eroded (e.g., scraped). Therefore, it is preferable that the surface of the charging member is smoother. For the above reasons, it is desirable that the ten-point average surface roughness Rz of the charging member surface of the present invention is 5 μm or less.

The ten-point average surface roughness Rz of the charging roller surface in the present invention is measured using a surface roughness measuring instrument SE-3400 manufactured by Kosaka Laboratory Co., Ltd. More specifically, the measuring device measures Rz at any five points of the charging roller, and uses the average value of the five points as the ten-point average surface roughness.

Considering the toner used from the viewpoint of the charging member of the present invention, the toner used together with the charging member of the present invention hardly adheres to the surface of the charging roller. Is preferred. Therefore, it can be said that a toner containing toner particles generated by a polymerization method is preferable. As described above, it is preferable to add an inorganic fine powder to the toner in order to reduce the adhesion of the toner particles.

[0108]

<Example 1> A charging roller as a charging member of the present invention was produced in the following manner. Epichlorohydrin rubber terpolymer 100 parts by weight (epichlorohydrin: ethylene oxide: allyl glycidiether = 40 mol%: 56 mol%: 4 mol%) Light calcium carbonate 30 parts by weight Aliphatic polyester plasticizer 10 parts by weight Stearic acid 1 part by weight Part Antioxidant MB (2-mercaptobenzimidazole) 0.5 part by weight Zinc oxide 5 parts by weight Quaternary ammonium salt 4 parts by weight The above materials were mixed in a closed mixer adjusted to 45 ° C.
Knead for a minute to prepare a raw material compound. In this compound, 1 part by weight of sulfur as a vulcanizing agent, 1 part by weight of DM (dibenzothiazyl sulfide) as a vulcanization accelerator, and TS (tetramethylthiuram monosulfide) are added to 100 parts by weight of epichlorohydrin rubber as a raw material rubber. 0.
5 parts by weight, and cooled to 20 ° C with a two-roll mill.
Knead for 0 minutes. The obtained compound is molded into a 6 mm stainless steel cored bar by using an extruder to form a roller having an outer diameter of 15 mm, and after heating and steam vulcanization, a wide polishing process is performed so that the outer diameter becomes 12 mm. An elastic layer was obtained.

A surface layer 2d shown below was formed on the above elastic layer by coating. As a material of the surface layer 2d, 100 parts by weight of a caprolactone-modified acrylic polyol solution (solid content: 20% by mass, solvent: MEK) 20 parts by weight of conductive tin oxide (titanate-based coupling agent-treated product) were mixed, and this mixed solution was mixed. Glass beads (average particle size φ1
mm) as a dispersion medium, and dispersed for 5 hours using a rigid sand mill. Thereafter, the glass beads were separated by filtration, and hexamethylene diisocyanate (HD
I) was added to give a ratio of (NCO / OH) = 0.35 to prepare a coating for a surface layer. After a coating material for a surface layer is coated on the surface of the elastic layer of the elastic roller by a dipping method, the temperature is set to 1 in a hot air circulating drier.
Dried at 50 ° C. for 1 hour. The thickness of the surface layer after drying is 1
It was 7 μm.

For the produced elastic roller (charging roller), the following items were measured. "Measurement of run-out of outer diameter difference of charging roller" Mitutoyo Corporation
Using a high-precision laser measuring machine LSM-403v, the variation in the outer diameter of the charging roller in the present example was measured. The roller outer diameter difference runout of the charging roller in this embodiment was 11.3 μm.

"Measurement of Charging Roller Crown Amount" High-precision laser measuring machine LSM-403v manufactured by Mitutoyo Corporation mentioned above.
Was used to measure the charging roller crown amount of the charging roller in this example. The roller crown amount of the charging roller in this embodiment was 55.4 μm.

"Measurement of hardness of charging roller" Kobunshi Keiki Co., Ltd.
The roller hardness of the charging roller in the present example was measured using an Asker-C rubber hardness meter manufactured by Toshiba Corporation. The roller hardness of the charging roller in this embodiment was 62.3 °.

[0113] The same binder resin as that forming the "surface layer measurement of the static friction coefficient mu _SB material" surface layer paint, coating the clear coating on an aluminum sheet, the static friction coefficient (mu _SB) for measurement Sample sheet. The static friction coefficient of this sample sheet was measured using a static friction coefficient measuring instrument, HEI.
The test was performed using DON Trabogear Muse TYPE 941 (manufactured by Shinto Kagaku Co., Ltd.). The static friction coefficient μ _SB was an average value of measured values at five arbitrary points on the sample sheet. The coefficient of static friction of the surface layer binder resin in this example was 0.23.

[0114] As described above, "static friction coefficient of the charging roller surface layer" were measured static friction coefficient mu _S of the charging roller surface in the present embodiment by using a measuring apparatus as shown in FIG. 4, the charging of the embodiment The coefficient of static friction on the roller surface is 0.2
It was 5.

[Measurement of Surface Roughness Rz of Charging Roller] In the present invention, a surface roughness measuring instrument SE-3 manufactured by Kosaka Laboratory Co., Ltd. is used.
The surface roughness of the charging roller was measured using the sample No. 400. 10-point average surface roughness Rz of the charging roller surface in this embodiment
Was 2.5 μm.

Further, a toner used in the present invention was prepared in the following manner. 0.1M in 700 parts by weight of ion exchange water
-Na ₃ PO ₄ aqueous solution 450 parts by weight were charged, followed by heating to 60 ° C., using a CLEAMIX CLS-30S (manufactured by M Technique Co., Ltd.), and stirred at 4500 rpm.
To this, 68 parts by weight of a 0.1 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing a calcium phosphate salt.

On the other hand, (monomer) styrene 160 parts by weight n-butyl acrylate 40 parts by weight (colorant) I. Pigment Blue 15: 3 10 parts by weight (charge control agent) di-t-butylsalicylic acid metal compound 2 parts by weight (polar resin) saturated polyester (acid value 15, peak molecular weight 12000) 10 parts by weight (release agent) Ester wax (Melting point: 60 ° C) 30 parts by weight (Crosslinking agent) 0.3 parts by weight of divinylbenzene The material described in the above formulation was heated to 60 ° C and uniformly dissolved.
Dispersed. The polymerization initiator 2,2′-azobis (2,2
5 parts by weight of 4-dimethylvaleronitrile) were dissolved to prepare a polymerizable monomer composition.

The polymerizable monomer composition was charged into the aqueous medium and stirred at 65 ° C. in a N ₂ atmosphere at 4500 rpm for 15 minutes using a CLEAR MIX to granulate the polymerizable monomer composition. did. Thereafter, while stirring with a paddle stirrer, the temperature was raised to 70 ° C., and the reaction was performed for 12 hours. After completion of the polymerization reaction, the remaining monomer was distilled off at 80 ° C./reduced pressure, and after cooling, hydrochloric acid was added to dissolve the calcium phosphate salt, followed by filtration, washing with water and drying to obtain colored resin particles (toner particles). . To 100 parts by weight of the obtained toner particles, as an external additive, 1.0 part by weight of hydrophobic silica particles having an average primary particle diameter of 10 nm and hydrotalcite compound compound particles having an average primary particle diameter of 450 nm (surface Unprocessed product)
Weight parts were externally added to obtain a cyan toner. The following measurement was performed on the obtained toner.

[Calculation of Toner Shape Factor] The shape factor was calculated by the above-mentioned FE-SEM manufactured by Hitachi, Ltd. The shape factor in this embodiment is shown below. SF-1 115 SF-2 121

"Measurement of Weight Average Particle Diameter of Toner" The weight average particle diameter of the toner in this example was measured using the Coulter Counter TA-II described above. The weight average particle size of the toner in this example was 6.74 μm.

An image was formed by an image forming apparatus using the above-described charging roller and toner, and the following evaluation test was performed on image formation using the charging roller and toner in this embodiment.

"Continuous Plural Sheet Image Output Durability Test When Only DC Voltage Is Applied to Charging Roller" The prepared charging roller was attached to the electrophotographic image forming apparatus shown in FIG.
Further, using cyan toner, environment 1 (temperature 23 ° C., humidity 55%), environment 2 (temperature 32.5 ° C., humidity 80%),
Under each environment of environment 3 (temperature 15 ° C., humidity 10%), an image output durability test of 10,000 continuous sheets was performed. By observing the obtained image visually, toner and external additives were attached to the charging roller, and the occurrence of fogging on the printing paper due to the adhesion was evaluated. Table 1 shows the results. ◎ in the table indicates that the obtained image is very good, ○
Is good, △ is slightly fogged in the halftone image,
X indicates that the halftone image has a clear image fog of the rotation period of the charging roller. As a result, in this example, a good image was obtained from the beginning, and an image which was almost the same as the initial image was obtained even after 10,000 images were output.

"Evaluation of Image Fogging Due to Adhesion of Toner and External Additives on Charging Roller" The image forming apparatus after performing the above-mentioned "continuous multiple-sheet image output durability test" of 10,000 sheets was left in the environment 3 for 24 hours. Image output evaluation was performed. By observing the obtained image visually, the toner adhered to the charging roller, and the occurrence of fogging on the printing paper due to the toner was evaluated. Table 1 shows the results. In the table, ◎ indicates that the obtained image is very good, ○ indicates that the image is good, Δ indicates that the halftone image has slight fog, and × indicates that the halftone image has a clear image of the charging roller rotation cycle. Show. In this environment, the effect of image fogging due to the adhesion of toner and external additives on the charging roller is most likely to appear. Therefore, the effect of toner adhesion and external additive adhesion can be evaluated in detail by performing such an image fogging evaluation after performing the “continuous plural-sheet image output durability test”. In this example, a good image was obtained even after the continuous multiple-image image output durability test, and an image that was almost the same as that at the beginning of the durability test was obtained.

Example 2 An elastic layer was obtained in the same manner as in Example 1 for the charging roller of this example. Surface layer 2d
As a material of the above, 100 parts by weight of a caprolactone-modified acrylic polyol solution (solid content: 20% by mass, solvent: MEK) 20 parts by weight of conductive tin oxide (titanate-based coupling agent-treated product) were mixed, and this mixed solution was mixed with glass beads ( Average particle size φ1
mm) as a dispersion medium, and dispersed for 5 hours using a rigid sand mill. Thereafter, the glass beads were separated by filtration, and hexamethylene diisocyanate (HD
I) was added to give a ratio of (NCO / OH) = 0.7 to prepare a coating for a surface layer. After a coating material for a surface layer is coated on the surface of the elastic layer of the elastic roller by a dipping method, the temperature is set to 1 in a hot air circulating drier.
Dried at 50 ° C. for 1 hour. The thickness of the surface layer after drying is 1
It was 5 μm.

The measurement was performed on the produced charging roller in the same manner as in Example 1. "Measurement of Deflection of Outer Diameter of Charging Roller" The fluctuation of the outer diameter of the charging roller in this embodiment was 31.3 μm.

[Measurement of Charging Roller Crown Amount] The roller crown amount of the charging roller in this embodiment was 61.5 μm.

[Measurement of Charging Roller Hardness] The roller hardness (Asker-C) of the charging roller in this embodiment is 69.2.
°.

[0128] The same binder resin as that forming the "surface layer measurement of the static friction coefficient mu _SB material" surface layer paint, coating the clear coating on an aluminum sheet, the static friction coefficient (mu _SB) for measurement Sample sheet. The coefficient of static friction of the surface layer binder resin in this example was 0.17.

[0129] As described above, "static friction coefficient of the charging roller surface layer" were measured static friction coefficient mu _S of the charging roller surface in the present embodiment by using a measuring apparatus as shown in FIG. 4, the charging of the embodiment The coefficient of static friction on the roller surface is 0.2
It was 8.

"Measurement of Surface Roughness Rz of Charging Roller" The 10-point average surface roughness Rz of the charging roller surface in this embodiment.
Was 2.1 μm.

This charging roller was evaluated in the same manner using the same toner as in Example 1. Table 1 shows the results.
Shown in As a result, in the durability test in this example, a good image was obtained from the beginning, and a good image was obtained even after outputting 10,000 images. Further, in the image fogging evaluation in this example, a good image was obtained even after the continuous multiple image output durability test.

Example 3 A charging roller as a charging member of the present invention was produced in the following manner. NBR 100 parts by weight Quaternary ammonium salt 3 parts by weight Ester plasticizer 25 parts by weight Calcium carbonate 30 parts by weight Zinc oxide 5 parts by weight Fatty acid 2 parts by weight
The mixture is kneaded for 20 minutes and further kneaded for 20 minutes with a closed mixer cooled to 20 ° C. to prepare a raw material compound. To this compound, 1 part by weight of sulfur as a vulcanizing agent and 3 parts by weight of Noxeller TS as a vulcanization accelerator are added to 100 parts by weight of NBR of the raw rubber, and kneaded for 10 minutes by a two-roll machine cooled to 20 ° C. The obtained compound is
mm around a stainless steel cored bar in an extruder so as to form a roller.
The elastic layer was obtained by polishing using a traverse method so as to obtain an elastic layer.

A surface layer as shown below was formed on the above elastic layer by coating. As a material for the surface layer 2d, 100 parts by weight of polyvinyl butyral resin (solid content: 50% by weight, solvent: ethanol), 45 parts by weight of conductive titanium oxide were mixed, and the mixed solution was applied by dipping to form a film having a thickness of 10 μm. To form a roller-shaped charging member (charging roller).

For the produced charging roller, the following items were measured in the same manner as in Example 1. "Measurement of Deflection of Outer Diameter of Charging Roller" The deviation of the outer diameter of the charging roller in this embodiment was 78.5 μm.

"Measurement of Charging Roller Crown Amount" The roller crown amount of the charging roller in this embodiment was 95.3 μm.

[Measurement of Charging Roller Hardness] The roller hardness (Asker-C) of the charging roller in this embodiment is 59.6.
°.

[0137] The same binder resin as that forming the "surface layer measurement of the static friction coefficient mu _SB material" surface layer paint, coating the clear coating on an aluminum sheet, the static friction coefficient (mu _SB) for measurement Sample sheet. The coefficient of static friction of the surface layer binder resin in this example was 0.34.

[0138] As described above, "static friction coefficient of the charging roller surface layer" were measured static friction coefficient mu _S of the charging roller surface in the present embodiment by using a measuring apparatus as shown in FIG. 4, the charging of the embodiment The coefficient of static friction on the roller surface is 0.4
It was 2.

"Measurement of the Surface Roughness Rz of the Charging Roller" The ten-point average surface roughness Rz of the charging roller surface in the present embodiment.
Was 1.8 μm.

With respect to this charging roller, the same evaluation was performed using the same toner as in Example 1. Table 1 shows the results.
Shown in As a result, in the durability test in this example, a good image was obtained from the beginning, and after a 10,000-image image was output, a good image was obtained although slight fog was observed in a part. Further, in the image fogging evaluation in this example, although a slight fog was observed in part, an almost satisfactory image was obtained even after the continuous multiple image output durability test.

Example 4 A toner was prepared in the same manner as in Example 1 except that the hydrotalcite-based compound particles used as the external additive were subjected to a hydrophobic treatment. The same evaluation as in Example 2 was performed using the same as in Example 2. Table 1 shows the results. In this example, the fog level of the image in the durability test was improved as compared with Example 2. This is considered to be an effect of hydrophobizing hydrotalcite-based compound particles used as a part of the external additive.

<Example 5> In the toner used in Example 2, titanium oxide particles (untreated surface / average primary particle diameter: 300 nm) were used in place of the hydrotalcite compound particles used as the external additive. A toner was prepared in the same manner as in Example 1 except that the toner was used, and the same evaluation as in Example 2 was performed using the same charging roller as that in Example 2. Table 1 shows the results. As a result, in the durability test in this example, a good image was obtained from the beginning, and after a 10,000-image image was output, a good image was obtained although slight fog was observed. Further, in the image fogging evaluation in this example, slight fog was recognized in the obtained image.

<Comparative Example 1> In Comparative Example 1, a charging roller was manufactured by the following method. 100 parts by weight of EPDM 30 parts by weight of conductive carbon black 5 parts by weight of zinc oxide 2 parts by weight of fatty acid 2 parts by weight of the above materials in a closed mixer adjusted to 60 ° C.
After kneading for 15 minutes, 15 parts by weight of paraffin oil is added to 100 parts by weight of EPDM, and the mixture is further kneaded with a closed mixer cooled to 20 ° C. for 20 minutes to prepare a raw material compound. In this compound, the raw rubber EPDM1
0.5 parts by weight of sulfur as a vulcanizing agent, 1 part by weight of MBT (2-mercaptobenzothiazole) as a vulcanization accelerator, 1 part by weight of TMTD (tetramethylthiuram disulfide), and 00 parts by weight of ZnMDC (dimethyldithiocarbamine) (Zinc acid) 1.5 parts by weight, and kneaded for 10 minutes in a two-roll machine cooled to 20 ° C. The obtained compound is placed around an outer diameter of φ1 around a φ6 mm stainless steel cored bar.
An elastic layer was obtained by performing heat vulcanization molding with a press molding machine so as to form a 2 mm roller.

A resistance layer as shown below was formed on the elastic layer by coating. As a material for the resistance layer 2c, 100 parts by weight of a polyurethane resin and 15 parts by weight of a conductive carbon black are dispersed and dissolved in a methyl ethyl ketone (MEK) solvent to prepare a coating for the resistance layer. This paint is applied on the elastic layer 2b by dipping to form a resistive layer 2c having a thickness of 100 μm.
Was formed by coating.

Further, a surface layer 2d shown below was formed on the resistance layer 2c by coating. As a material for the surface layer 2d, 100 parts by weight of a polyamide resin and 10 parts by weight of conductive tin oxide are dispersed and dissolved in a mixed solvent of methanol / toluene to prepare a coating material for a surface layer. This coating material was applied by a dipping method to coat a surface layer having a thickness of 5 μm to obtain a roller-shaped charging member.

With respect to the produced elastic roller (charging roller), the following items were measured in the same manner as in Example 1. "Measurement of Deflection of Outer Diameter of Charging Roller" The deflection of the outer diameter of the charging roller in this comparative example was 90.2 μm.

"Measurement of Charging Roller Crown Amount" The roller crown amount of the charging roller in this comparative example was 87.5 μm.

"Measurement of Charging Roller Hardness" The roller hardness (Asker-C) of the charging roller in this comparative example is 85.2.
°.

[0149] The same binder resin as that forming the "surface layer measurement of the static friction coefficient mu _SB material" surface layer paint, coating the clear coating on an aluminum sheet, the static friction coefficient (mu _SB) for measurement Sample sheet. The static friction coefficient of the surface layer binder resin in this comparative example was 0.71.

[0150] As described above, "static friction coefficient of the charging roller surface layer" were measured static friction coefficient mu _S of the charging roller surface in this comparative example using a measuring apparatus as shown in FIG. 4, the charging of the comparative example The coefficient of static friction on the roller surface is 1.0
It was 3.

"Measurement of Surface Roughness Rz of Charging Roller" Ten points average surface roughness Rz of the charging roller surface in this comparative example.
Was 7.9 μm.

Further, a toner used in this comparative example was prepared in the following manner. (Resin) Styrene / butyl acrylate copolymer resin 100 parts by weight (Coloring agent) Phthalocyanine blue 5 parts by weight (Charge control agent) Di-t-butylsalicylic acid metal compound 2 parts by weight is mixed, and a biaxial extruder (L / D) = 30). After cooling, the kneaded product was roughly pulverized with a hammer mill and further finely pulverized with a jet mill to obtain colored resin particles (toner particles). To 100 parts by weight of the obtained toner particles, 1.5 parts by weight of hydrophobic silica particles having an average primary particle diameter of 10 nm were externally added as an external additive to obtain a cyan toner. The following measurement was performed on the obtained toner in the same manner as in Example 1.

[Calculation of Toner Shape Factor] The shape factor was calculated by the above-mentioned FE-SEM manufactured by Hitachi, Ltd. The shape factor in this comparative example is shown below. SF-1 162 SF-2 130

"Measurement of Toner Weight Average Particle Diameter" The toner of this comparative example was measured for weight average particle diameter using the Coulter Counter TA-II described above. The weight average particle diameter of the toner in this comparative example was 6.8 μm.

With respect to the charging roller, the same evaluation as in Example 1 was performed using the toner produced by the pulverization method described above. Table 1 shows the results. When an image formation durability test was performed on a plurality of sheets using an image forming apparatus using the charging roller and the toner, a low-temperature and low-humidity environment (15 ° C., 10%)
In this case, as the durability test progressed, the image defect was particularly conspicuous. Further, in the durability test for image output on a plurality of sheets, unevenness in image density due to toner adhesion occurred.

Comparative Example 2 In Comparative Example 2, a charging roller was manufactured by the following method. NBR 100 parts by weight Carbon black 50 parts by weight Calcium carbonate 30 parts by weight Zinc oxide 5 parts by weight Fatty acid 2 parts by weight
After kneading for 100 minutes, 100 parts by weight of NBR
(Dioctyl sebacate) Add 20 parts by weight of plasticizer and add
The mixture is further kneaded for 20 minutes by a closed mixer cooled to 0 ° C. to prepare a raw material compound. To this compound, 1 part by weight of sulfur as a vulcanizing agent and 3 parts by weight of Noxeller TS as a vulcanization accelerator are added to 100 parts by weight of NBR of the raw rubber, and kneaded for 10 minutes by a two-roll machine cooled to 20 ° C. The obtained compound is molded in a roller shape around a φ6 mm stainless steel core using an extrusion molding machine, and then heated and vulcanized, and then polished by a traverse method so as to have an outer diameter of φ12 mm. Layer obtained.

A surface layer 2d as shown below was formed on the elastic layer by coating. As a material for the surface layer 2d, 100 parts by weight of a polyurethane elastomer and 35 parts by weight of conductive tin oxide are dispersed and dissolved in a methyl ethyl ketone (MEK) solvent to prepare a coating for a surface layer. Using this coating material, a surface layer having a film thickness of 10 μm was formed by coating by a dipping method to obtain a roller-shaped charging member.

With respect to the produced elastic roller (charging roller), the following items were measured in the same manner as in Example 1. "Measurement of Deflection of Outer Diameter of Charging Roller" The deflection of the outer diameter of the charging roller in this comparative example was 102.2 μm.

[Measurement of Charging Roller Crown Amount] The roller crown amount of the charging roller in this comparative example was 85.3 μm.

[Measurement of Charging Roller Hardness] The roller hardness (Asker-C) of the charging roller in this comparative example was 82.1.
°.

[0161] The same binder resin as that forming the "surface layer measurement of the static friction coefficient mu _SB material" surface layer paint, coating the clear coating on an aluminum sheet, the static friction coefficient (mu _SB) for measurement Sample sheet. The static friction coefficient of the surface layer binder resin in this comparative example was 0.79.

[0162] As described above, "static friction coefficient of the charging roller surface layer" were measured static friction coefficient mu _S of the charging roller surface in this comparative example using a measuring apparatus as shown in FIG. 4, the charging of the comparative example The coefficient of static friction of the roller surface is 1.1
It was 4.

“Measurement of Surface Roughness Rz of Charging Roller” Ten points average surface roughness Rz of the charging roller surface in this comparative example
Was 8.2 μm.

With respect to this charging roller, the same evaluation as in Example 1 was performed using the same toner as in Comparative Example 1. Table 1 shows the results. In an image output by an image forming apparatus using the charging roller, roughness occurred on a halftone image from about 5000 continuous sheets.

[0165]

[Table 1]

[0166]

As described above, according to the present invention, an essential cleaning device as a dedicated device for removing the toner remaining on the image carrier after the transfer process is not required, and the simultaneous development is possible. An image forming apparatus employing a cleaning method (cleanerless method) can be provided. In the image forming apparatus of the present invention, since the toner and the external additive do not adhere to the surface of the charging member, image fogging and image unevenness caused by the adhesion can be prevented. As a result, the total number of prints of the image forming apparatus employing the developing synchronous cleaning method (cleanerless method) is greatly increased, and the effect of further improving the durability stability is achieved. In addition, even in a low-temperature and low-humidity environment, an effect of preventing image fogging caused by the adhesion of toner and external additives does not occur.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention.

FIG. 2 is a schematic view showing an example of a charging roller as a charging member of the present invention.

FIG. 3 is a schematic view showing another example of a charging roller as a charging member of the present invention.

FIG. 4 is a schematic view showing another example of the charging roller as the charging member of the present invention.

FIG. 5 is a schematic view showing an apparatus for measuring a static friction coefficient of a surface layer of a charging roller as a charging member of the present invention.

6 is a diagram illustrating an example of a chart when measurement is performed using the static friction coefficient measurement device illustrated in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier (electrophotographic photoreceptor) 2 Charging member (charging roller) 3 Image exposure means 4 Developing means 4a Toner carrier 4b Stirring member 4c Toner magnetic member 5 Transfer means L Laser light S1 Charging bias application power source S2 Transfer bias application Power supply P Transfer material

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 9/087 G03G 9/08 384 15/08 507 15/08 507B (72) Inventor Hiroyuki Nagata Ota, Tokyo 3-72, Shimomaruko-ku, Canon Inc. (72) Inventor Seiji Tsuru 3-2-2, Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroshi Inoue 3-chome, Shimomaruko, Ota-ku, Tokyo No.30 No.2 Canon Inc. F term (reference) 2H003 AA12 BB11 CC05 2H005 AA08 AB06 CB07 CB13 DA07 EA05 2H077 AA37 AC16 AD06 AD31 CA11 GA04 3J103 AA02 AA14 AA21 AA51 AA61 BA41 FA30 GA02 GA57 GA05 HA05 HA03 HA04 HA32 HA33 HA36 HA37 HA42 HA43 HA46 HA47 HA48 HA52 HA53

Claims (22)

[Claims] 1. A photoconductor, a charging unit that charges the photoconductor by a charging member that contacts the photoconductor, and an exposure unit that exposes the charged photoconductor to form an electrostatic latent image on the photoconductor. Developing means for supplying toner to the photoreceptor on which the electrostatic latent image is formed to form a toner image corresponding to the electrostatic latent image on the photoreceptor, and transferring the toner image on the photoreceptor to a transfer material Means, the charging member is formed in a roller shape having a conductive support and one or more coating layers formed thereon, and the roller outer diameter difference fluctuation of the charging member is The coefficient of static friction on the surface of the charging member is equal to or less than the roller crown amount of the charging member.
0 or less, and the surface roughness (Rz) of the charging member is 5 μm.
m or less. 2. The image forming apparatus according to claim 1, wherein the developing unit includes a unit that collects toner remaining on the photoconductor after transfer. 3. The image forming apparatus according to claim 1, wherein the toner contains toner particles and inorganic fine powder. 4. The toner has an average primary particle diameter of 4-5.
4. The image forming apparatus according to claim 3, wherein the image forming apparatus contains 00 nm inorganic fine powder. 5. The image forming apparatus according to claim 3, wherein the toner contains an inorganic fine powder whose surface is subjected to a hydrophobic treatment. 6. The image forming apparatus according to claim 3, wherein the toner particles of the toner are toner particles generated by using a polymerization method, and have a spherical shape. 7. The image forming apparatus according to claim 1, wherein the coating layer of the charging member has a laminated structure in which at least an elastic layer and a surface layer are formed in this order. 8. The charging member has a roller hardness of 30 to 75.
The image forming apparatus according to claim 7, wherein the angle is degrees. 9. A process cartridge detachably mounted to an image forming apparatus main body, the process cartridge comprising: a photosensitive member; charging means for charging the photosensitive member by a charging member in contact with the photosensitive member; Developing means for supplying toner to the electrostatic latent image formed on the body to form a toner image corresponding to the electrostatic latent image on the photoreceptor, wherein the charging member is a conductive support And a roller having at least one coating layer formed thereon, wherein the roller outer diameter difference fluctuation of the charging member is equal to or less than the roller crown amount of the charging member, and the surface of the charging member is The coefficient of static friction is 1.
0 or less, and the surface roughness (Rz) of the charging member is 5 μm.
m or less. 10. A photoconductor, charging means for charging the photoconductor by a charging member in contact with the photoconductor, and exposure means for exposing the charged photoconductor to form an electrostatic latent image on the photoconductor. Developing means for supplying toner to the photoreceptor on which the electrostatic latent image is formed to form a toner image corresponding to the electrostatic latent image on the photoreceptor, and transferring the toner image on the photoreceptor to a transfer material Wherein the charging member is formed in a roller shape having a conductive support and one or more coating layers formed thereon, wherein the roller is a roller for the charging member. The deviation of the outer diameter is equal to or less than the roller crown amount of the charging member, and the static friction coefficient of the surface of the charging member is 1.
0 or less, and the surface roughness (Rz) of the charging member is 5 μm.
m or less, wherein the toner contains toner particles and inorganic fine powder. 11. The toner has an average primary particle diameter of 4 to 10.
The toner according to claim 10, further comprising an inorganic fine powder of 500 nm. 12. The toner according to claim 1, wherein the toner contains an inorganic fine powder whose surface is subjected to a hydrophobic treatment.
12. The toner according to 0 or 11. 13. The toner according to claim 10, wherein the toner particles of the toner are toner particles generated by a polymerization method and are spherical. 14. The toner according to claim 10, wherein the coating layer of the charging member has a laminated structure in which at least an elastic layer and a surface layer are formed in this order. 15. A roller hardness of the charging member is 30-7.
The toner according to claim 14, wherein the angle is 5 °. 16. A photoreceptor, charging means for charging the photoreceptor by a charging member in contact with the photoreceptor, exposure means for exposing the charged photoreceptor to form an electrostatic latent image on the photoreceptor. Developing means for supplying toner to the photoreceptor on which the electrostatic latent image is formed to form a toner image corresponding to the electrostatic latent image on the photoreceptor, and transferring the toner image on the photoreceptor to a transfer material The charging member is formed in a roller shape having a conductive support and at least one coating layer formed thereon, and the charging member is provided outside the roller of the charging member. The diameter difference fluctuation is equal to or less than the roller crown amount of the charging member, and the static friction coefficient of the surface of the charging member is 1.
0 or less, and the surface roughness (Rz) of the charging member is 5 μm.
m or less. 17. The charging member according to claim 16, wherein the coating layer of the charging member has a laminated structure in which at least an elastic layer and a surface layer are formed in this order. 18. The charging member has a roller hardness of 30 to 75.
18. The charging member according to claim 17, wherein the angle is degrees. 19. The charging member according to claim 16, wherein the toner contains toner particles and inorganic fine powder. 20. The toner having an average primary particle diameter of 4 to 20.
20. The charging member according to claim 19, further comprising a 500 nm inorganic fine powder. 21. The toner according to claim 1, wherein the toner contains an inorganic fine powder whose surface is subjected to a hydrophobic treatment.
21. The charging member according to 9 or 20. 22. The charging member according to claim 19, wherein the toner particles of the toner are toner particles generated by a polymerization method and are spherical.