JP2003207987A - Image forming apparatus, process cartridge, toner and conductive member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus with excellent durability and stability which prevents image fogging and nonuniformity in image density caused by the attachment of toner and an external additive to a charging roller in spite of the adoption of a developing and cleaning system and to provide a process cartridge, toner to be used in the apparatus and the cartridge and a conductive member. <P>SOLUTION: The image forming apparatus includes a charging means which is provided with a photoreceptor 1 and the conductive charging roller 2 arranged in contact with the photoreceptor 1 and charges the photoreceptor 1 by applying voltage on the roller 2, an exposing means 3 for exposing the charged photoreceptor 1 and forming an electrostatic latent image on the photoreceptor 1, a developing means 4 for forming a toner image on the photoreceptor 1 on which the electrostatic latent image is formed and a transfer means 5 for transferring the toner image on the photoreceptor 1 to a transfer material P. Toner containing toner particles and inorganic fine powder is used for the image forming apparatus. The glass transition temperature of the surface layer of the charging roller 2 is set to be higher than the surface temperature of the photoreceptor 1 when the image is formed. <P>COPYRIGHT: (C)2003,JPO

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 adopting an electrophotographic system such as a printer, a facsimile and a copying machine. The present invention relates to a conductive member that electrically controls 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 a forming apparatus. More specifically, a charging member to which a voltage is applied contacts an object to be charged. The present invention relates to a contact charging member that charges an object to be charged.

[0002]

2. Description of the Related Art As an electrophotographic image forming apparatus,
A rotary drum type photoconductor that uses a photoconductive material, a charging unit that uniformly and evenly charges the surface of the photoconductor to a predetermined polarity and potential, and imagewise exposure to the uniformly charged surface of the photoconductor. Image exposure means for forming an electrostatic latent image corresponding to image information (laser light scanning exposure means, projection image forming exposure means for document image, etc.), and developing means for developing the formed electrostatic latent image as a toner image. , Transfer means for transferring the toner image from the photoconductor side to a transfer material such as paper, fixing means for fixing the toner image on the transfer material by heat or pressure, and the toner image after the transfer remains without being transferred. An image forming apparatus having a cleaning unit that removes toner to clean the surface of the photoconductor is generally known.

In the above image forming apparatus, various configurations are known as the above-mentioned means and the like. In recent years, such image forming apparatuses have been reduced in size, but there has been a limit only in reducing the size of the photosensitive member and each device that constitute the apparatus.

Further, the above-mentioned image forming apparatus has a problem regarding the cleaning means. As a cleaning means,
Generally, a cleaning member such as a blade, a fur brush, or a roller is brought into contact with the surface of the photoconductor to mechanically scrape off or stop the transfer residual toner and collect it in a waste toner container. There is a problem that abrasion of the photoconductor occurs due to contact, and the life of the photoconductor is shortened. Further, the toner collected in the waste toner container becomes waste toner, and from the viewpoint of ecology, a system that does not produce effective use of toner has been desired.

Therefore, the cleaning means for cleaning the toner remaining on the surface of the photosensitive member after the transfer of the toner image onto the transfer material is also used as the developing means, thereby eliminating the need for the cleaning means as a dedicated device or the cleaning / cleaning without cleaner. An image forming apparatus called "A" has also appeared (Japanese Patent Laid-Open Nos. 59-133573, 62-203182, 63-133179, and 64-2058).
No. 7, JP-A No. 2-511168, and No. 2-302.
772, 5-2287, 5-2289.
Gazette, gazette 5-53482 gazette, gazette 5-61383 gazette, etc.).

The development / cleaning is a direct-current voltage applied to the toner carrier at the time of development after the next step by the toner carrier (developing member) of the developing means for the transfer residual toner carried to the developing area by the rotation of the photoconductor. And the fog-removing potential difference Vback, which is the potential difference between the photoconductor surface potential and the photoconductor surface potential. According to this, even without a cleaning unit as a dedicated device, the transfer residual toner is collected by the developing unit and used for the development in the subsequent steps, so that the waste toner can be eliminated. Further, since the cleaning means as a dedicated device is not provided, there is a great advantage in terms of space, and the image forming apparatus can be greatly downsized.

On the other hand, a corona charger and a contact charger are known as the charging means used in the above-mentioned image forming apparatus. The corona charger is placed in a non-contact manner with the discharge opening facing the photoconductor, and the photoconductor surface is exposed to the corona shower emitted from the discharge opening so that the photoconductor surface has a predetermined polarity and potential. It is to be charged. However, there are problems that a high voltage power source is required and that a relatively large amount of ozone is generated.

On the other hand, in the contact charger, a charging member which is a conductive member such as a roller type, a blade type, a brush type or a magnetic brush type is brought into contact, and a predetermined charging bias is applied to the contact charging member so that the photosensitive member is exposed. It uniformly charges the body surface to a predetermined polarity and potential. Compared to corona chargers, contact chargers have advantages such as lower power supply voltage, less ozone generation, and lower power consumption. Recently, contact chargers have been attracting attention. There is. Above all, a roller charging type charging means using a conductive roller (charging roller) as a contact charging member is preferably used from the viewpoint of charging stability.

In the above charging roller, a resistance layer is provided on a conductive support, or at least an elastic layer and a resistance layer are provided on a conductive support, and the upper resistance layer retains an appropriate volume resistance, and the lower layer. By holding the elastic layer of the appropriate elasticity for proper contact with the charged body, the charging uniformity of the charged body and leakage due to pinholes or scratches on the surface of the charged body such as the photoconductor There are known ones for prevention.

As the elastic layer, a layer in which conductive powder such as carbon black, graphite, metal powder or metal oxide is dispersed in an elastic material is used. As the elastic material, 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), urethane rubber (U), silicone rubber (VMQ)
Synthetic rubbers such as, natural rubber (NR), styrene butadiene styrene (SBS), thermoplastic elastomers such as polyolefins and polyurethanes, and mixtures thereof are used.

The elastic layer contains a considerably large amount of conductive powder or the like in the elastic material in order to reduce the resistance required. However, the addition of a large amount of conductive powder or the like results in increasing the hardness of the elastic material. A considerably large amount of softening oil or plasticizer is added in order to lower the required amount. Note that the elastic layer is often formed by die molding or the like.

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

[0013]

The conventional charging roller has the following problems.
An extremely small amount of toner and external additives that have slipped through the cleaning process accumulate on the surface of the charging roller as the total number of printed sheets increases, making it impossible to uniformly charge the photoconductor and causing slight density unevenness on the image. Was occurring. The adhesion of the toner and the external additive to the surface of the charging roller has been a problem for improving the image quality and durability of the image forming apparatus.

In particular, when a conventional charging roller is attached to a cleanerless type image forming apparatus, there is a problem that the toner and the external additive remaining on the photoconductor are likely to adhere. That is, in the cleanerless system, the photoconductor is charged by the charging roller in the state where the untransferred residual toner and the external additive are present on the photoconductor. Therefore, the toner and the external additive are likely to adhere to the charging roller. If toner and external additives adhere to the charging roller, it becomes impossible to uniformly charge the photoconductor as the total number of printed sheets increases, causing fog and uneven density on the image, and durability stability. I had a problem with. In particular, in a low temperature and low humidity environment, image fog and image density unevenness caused by the adhesion of toner and external additives remarkably appear, which is a problem.

It is an object of the present invention to provide an image forming apparatus and a process cartridge which do not cause image fog or image density unevenness due to the adhesion of toner and external additives to the charging roller.

Another object of the present invention is to provide a toner which does not easily adhere to the surface of the charging member, and a conductive member which is used in the contact charging system and which does not easily adhere to the toner or external additives.

Another object of the present invention is to provide an image forming apparatus adopting a developing / cleaning system or a cleanerless system.

Another object of the present invention is to provide an image forming apparatus having excellent durability and stability.

[0019]

In order to achieve the above object, the present invention has a photosensitive member and a conductive charging member provided in contact with the photosensitive member, and a photosensitive member is formed by applying a voltage to the charging member. Charging means for charging the body, exposing means for exposing the charged photoreceptor to form an electrostatic latent image on the photoreceptor, and developing means for forming a toner image on the photoreceptor on which the electrostatic latent image is formed, In an image forming apparatus having a transfer means for transferring a toner image on a photoconductor onto a transfer material, the toner forming the toner image contains toner particles and inorganic fine powder and forms the surface of the charging member. Provided is an image forming apparatus characterized in that a glass transition temperature of a material is higher than a surface temperature of a photoconductor during image formation.

In the above image forming apparatus, the glass transition temperature is preferably a dispersion peak temperature of tan δ in dynamic viscoelasticity measurement, and the image forming apparatus according to claim 1. Further, it is preferable that the developing means also serves as a means for collecting the toner remaining on the photoconductor after the transfer.

Further, the present invention is used in the above-mentioned image forming apparatus, has at least a photoconductor and a developing means, and is constructed such that the constituent elements are integrated and are detachable from the main body of the image forming apparatus. A process cartridge characterized by the following is provided.

Further, according to the present invention, there are provided a photosensitive member, a charging means having a conductive charging member provided in contact with the photosensitive member, for charging the photosensitive member by applying a voltage to the charging member, and a charged photosensitive member. Exposure means for exposing to form an electrostatic latent image on the photoreceptor,
The glass transition of the material forming the surface of the charging member, which has a developing means for forming a toner image on the photoconductor on which the electrostatic latent image is formed and a transfer means for transferring the toner image on the photoconductor to a transfer material. A toner used in an image forming apparatus having a temperature higher than the surface temperature of a photoconductor at the time of image formation and forming a toner image, characterized by containing toner particles and inorganic fine powder. To do.

In the above toner, the average primary particle diameter is 4 to 5
The toner preferably contains an inorganic fine powder of 00 nm, more preferably a toner containing the inorganic fine powder whose surface is hydrophobized, and even more preferably spherical particles produced by a polymerization method.

Further, the present invention is a conductive member, which is provided in contact with a charged body to which the above-mentioned toner adheres, for charging the charged body, the glass transition temperature of the material constituting the surface of the conductive member. However, it is higher than the surface temperature of the charged body at the time of contact with the conductive member.

In the above conductive member, the glass transition temperature is preferably the dispersion peak temperature of tan δ in the dynamic viscoelasticity measurement, the ten-point average surface roughness is more preferably the toner particle size or less, and the roller shape is preferable. It is more preferable that the conductive member is the charging member of the image forming apparatus described above, and the charged body is the photoconductor of the image forming apparatus described above.

The present invention, by virtue of the above construction, makes it possible to provide an image forming apparatus which is excellent in durability and stability and which adopts a developing / cleaning system or a cleanerless system.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described. (1) Image Forming Apparatus FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention. The image forming apparatus of the present example includes a contact charging type charging unit having a photosensitive member 1 and a charging roller 2 which is a charging member and is provided in contact with the photosensitive member 1, an exposure unit 3, a developing unit 4, and a transfer unit. And a transfer type electrophotographic image forming apparatus. The image forming apparatus of this example is not provided with an independent cleaning means as introduced in the conventional example, and is configured as a developing / cleaning type (cleanerless) image forming apparatus using a reversal developing method.

The photosensitive member 1 is a rotary drum type electrophotographic photosensitive member as a so-called image bearing member, and is rotationally driven at a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow. As the photoreceptor 1, various conventionally known photoreceptors (or image carriers) such as an amorphous photoreceptor and an OPC photoreceptor having an organic photosensitive layer can be used.

The charging means is a contact charging type charging means using a charging roller as a charging member.
And a charging bias applying power source S1. Charging roller 2
Is brought into contact with the photoconductor 1 with a predetermined pressing force. In this example, the charging roller is driven to rotate at a peripheral speed different from that of the photoconductor 1. A charging bias application power source S is applied to the charging roller 2.
1 to a predetermined DC voltage (referred to as DC voltage. For example, -13
00V), the surface of the photoconductor 1 is uniformly charged to a predetermined polarity potential (for example, dark part potential −700V).

Referring to the charging voltage here, a DC voltage or a voltage obtained by superposing a DC voltage or an AC voltage (referred to as an AC voltage) and a DC voltage can be used for charging the photosensitive member 1. As the waveform of the AC voltage, a sine wave, a rectangular wave, a triangular wave or the like can be appropriately used. In addition, the DC power supply is periodically turned on /
It may be a rectangular wave formed by turning off. As described above, as the waveform of the AC voltage, a bias whose voltage value periodically changes can be used.

The charging roller 2 will be described in detail later, but is a roller member in which a conductive or elastic layer made of rubber or resin is formed around a core metal. The charging roller 2 is designed in advance so that the glass transition temperature of the material forming the surface of the charging roller 2 is higher than the surface temperature of the photoconductor 1 during image formation.

The exposing means 3 is means for exposing the charged photoconductor 1 to form an electrostatic latent image on the photoconductor 1, and is, for example, a laser beam scanner. The exposure unit 3 is not particularly limited as long as it can perform exposure according to the image to be formed, and various conventionally known exposure units can be used. By the exposure means 3 performing image exposure L on the uniformly charged surface of the photoconductor 1 corresponding to the image information for the image purpose, the potential of the exposed light portion of the charged surface of the photoconductor 1 (for example, light portion potential −120 V). ) Is selectively reduced (attenuated) to form an electrostatic latent image.

The developing means 4 is a developing container for accommodating toner (negative toner in this example), and a portion rotatably provided at the opening of the developing container and carrying the toner in the developing container and facing the photoconductor 1. A toner carrier 4a conveyed to the developing area,
Supply roller 4b for supplying toner to the toner carrier 4a
And a toner layer pressure regulating member 4c for regulating the toner on the toner carrier 4a to form a uniform toner layer on the toner carrier 4a. The toner will be described in detail later, but in this example, a non-magnetic one-component toner containing toner particles and inorganic fine powder is used as the toner.

The developing means 4 is a reversal developing means, and toner (negative toner) charged with the same polarity as the charging polarity of the photoconductor 1 is applied to the exposed portion of the electrostatic latent image on the photoconductor surface with the toner carrier 4a. A developing bias (for example, −350 V) is applied to the toner to selectively attach the toner to visualize the electrostatic latent image as a toner image.

The transfer means has a conductive transfer roller that contacts the photosensitive member 1 with a predetermined pressing force to form a transfer nip portion, and a transfer bias applying power source S2. The transfer roller 5 rotates in the forward direction of the rotation of the photoconductor 1 at a peripheral speed substantially the same as the peripheral speed of rotation of the photoconductor 1. In addition, the transfer roller 5 is
A transfer voltage having a polarity opposite to the charging polarity of the toner is applied from the transfer bias applying power source S2. The transfer material P is fed to the transfer nip portion from a paper feed mechanism portion (not shown) at a predetermined control timing, and the back surface of the transfer material P is opposite to the charging polarity of the toner by the transfer roller 5 to which the transfer voltage is applied. By being charged with 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 roller 5 is the charging roller 2 described above.
Similarly to the above, a conductive elastic layer is formed around the core metal, and a conventionally known conductive roller member may be used for the transfer roller 5, or the charging roller 2 may be used.
You may use the thing similar to. The transfer means is not limited to the one using the transfer roller 5, and various conventionally known transfer means such as a transfer means using an intermediate transfer body can be used.

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

Residuals on the photoconductor such as transfer residual toner are conveyed from the transfer nip portion to the charging nip portion (a portion where the charging roller 2 and the photoconductor 1 face each other) while remaining on the photoconductor 1.
The charging roller 2 charges the photoreceptor to the same polarity. Then, the transfer residual toner reaches the developing unit 4 through the exposure unit, is electrically captured by the back contrast on the toner carrier 4a, and is collected in the developing container.
That is, in the image forming apparatus of this example, the developing means 4 also serves as a means for collecting the toner remaining on the photoconductor 1 after the transfer, and thus the development / cleaning (cleanerless) is realized.

According to the above-mentioned image forming apparatus, the transfer residual toner contacts the charging roller 2, but the glass transition temperature of the material forming the surface of the charging roller 2 is higher than the temperature of the surface of the photoconductor 1 at the time of image formation. Because it is set high,
The transfer residual toner is less likely to adhere to the charging roller 2, and charging failure due to the transfer residual toner adhesion and formation of a defective image due to the charging failure are suppressed.

In the image forming apparatus, since the developing unit 4 also serves as a unit for collecting the transfer residual toner, the photosensitive member 1 can be stably and uniformly charged without providing an independent cleaning unit. It is more preferable from the viewpoint of further downsizing of the image forming apparatus and ecology.

Further, in the present invention, it is possible to use a process cartridge in which two or more kinds of members, means, etc. are integrally formed and detachably attached to the main body of the image forming apparatus.
The process cartridge can be replaced with a plurality of means at the same time from the above configuration, and can be an effective configuration depending on the suitable arrangement of each means or the like, or the presence of members or the like in contact with each other.

The process cartridge is integrally constituted by a holding member for holding the above-mentioned means and members in the arrangement for image formation, while the image-forming apparatus main body integrally holds the means. It can be configured by providing a guide member that guides the integrated structure to the arrangement position at the time of image formation in this state. The holding member may be a conventionally known resin frame or the like, and the guide member may be a conventionally known rail or the like.

As a process cartridge preferable in the present invention, for example, a process cartridge in which the photoconductor 1, the developing means 4 and the charging roller 2 are integrally and detachably constructed can be exemplified. The process cartridge is not limited to the above configuration, and the constituent elements of the process cartridge can be arbitrarily selected according to the type of each means or member used in the image forming apparatus.

According to the process cartridge as described above, maintenance of the image forming apparatus can be made easier.

(2) Developer (Toner) The toner of the present invention is characterized by containing an inorganic fine powder as an external additive, and is used in the image forming apparatus of the present invention described above. The toner of the present invention is composed of toner particles and inorganic fine powder.

The above-mentioned toner particles are preferably spherical from the viewpoint of uniform charging property and improvement of transfer efficiency, and such toner particles can be preferably produced by a polymerization method. Further, the spherical toner hardly adheres to the surface of the conductive member. Here, desirable physical properties of toner particles will be described.

The shape of the toner particles can be obtained by analyzing the toner particle image. In the present invention, the shape factor SF-1 calculated by the following formula using the absolute maximum length of the toner particle in the toner particle image, the projected area of the toner particle, and the circumferential length of the toner particle image as an index representing the shape of the toner particle And SF-2 are preferably used.

[0048]

## EQU1 ## SF-1 = (MXLNG) ² / AREA × (π
/ 4) × 100 [wherein MXLNG represents the absolute maximum length of the toner particles,
AREA indicates the projected area of the toner particles. ]

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

The shape factor SF-1 indicates the degree of roundness of the toner particles, and SF-2 indicates the degree of unevenness of the toner particles. As a preferable measurement method of SF-1 and SF-2, 100 toner images magnified 500 times by using Hitachi FE-SEM (S-800) are randomly sampled, and the image information is An image analyzer (LuzexII
An example is a method in which the shape factor is calculated by introducing it into I), performing analysis, and using the above formula.

The toner particles have a shape factor SF-1 of 10.
0 to 150, and the shape factor SF-2 is 100 to 1
It is preferably 40. If the shape factor of the toner particles is in the above range, the shape of the toner particles can be understood to be almost spherical. If the shape factor is out of the above range, the shape of the toner particles becomes complicated, and the fluidity of the toner, the uniformity of charging, and the releasability may deteriorate.

The toner particles have a weight average particle diameter of 3 to 10
It is preferably μm. When the weight average particle diameter of the toner particles is smaller than 3 μm, the cohesive force between the toner particles becomes strong, and there is a risk that the fluidity of the toner will be reduced and uneven charging will occur. If the weight average particle diameter of the toner particles is larger than 10 μm, the developability may be deteriorated, and the faithful reproduction of the latent image may not be possible.

The above-mentioned weight average particle diameter can be adjusted in the above-mentioned polymerization method by the production conditions of toner particles, the classification of toner particles produced, and the like. The method for measuring the weight average particle diameter is not particularly limited, but for measuring the weight average particle diameter in the present invention, it is preferable to use Coulter Counter TA-II or Coulter Multisizer II (manufactured by Coulter, Inc.) as a measuring device. .

The type of toner in the present invention is not particularly limited, but a non-magnetic one-component developer is preferably used. As the non-magnetic one-component toner particles, it is preferable to use toner particles produced by a polymerization method. In particular, since the toner particles formed by polymerizing the surface layer portion of the toner particles are produced by polymerizing the monomer composition in a dispersion medium, the surface of the toner particles can be obtained as a considerably smoothed spherical shape. it can.

As the above-mentioned polymerization method, various polymerization methods such as an emulsion polymerization method have been conventionally known, but the toner of the present invention is preferably produced by a suspension polymerization method. The suspension polymerization method forms droplet particles of a monomer composition containing a polymerizable monomer, a colorant, a release agent, etc. in an aqueous medium containing a dispersion stabilizer as necessary (suspension). In this state, a polymerization initiator or a crosslinking agent is optionally used to polymerize the polymerizable monomer. Various materials used in the toner of the present invention will be described below.

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. , Methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate,
Acrylic esters such as n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, Methacrylic acid n-
Methacrylic acid esters such as butyl, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. Other acrylonitrile, methacrylic acid Examples include monomers such as ronitrile and acrylamide. These monomers may be used alone or in combination. Among the above-mentioned monomers, it is preferable to use styrene or a styrene derivative alone or in combination with other monomers, from the viewpoint of developing characteristics and durability of the toner.

In the present invention, it is more preferable to add a polar group-containing polymer / copolymer as an additive to the monomer composition for polymerization. Since the polar polymer / copolymer gathers in the surface layer of the toner particles, it becomes a kind of shell-like form and imparts excellent properties such as blocking resistance to the toner particles. By polymerizing so as to contribute to the improvement of fixing properties with a relatively low molecular weight,
It is possible to obtain a toner that satisfies the conflicting requirements of fixability and blocking resistance.

Examples of polar polymers / copolymers usable in the present invention include dimethylaminoethyl methacrylate,
Polymers of nitrogen-containing monomers such as diethylaminoethyl methacrylate or copolymers with styrene / unsaturated carboxylic acid esters, nitrile-based monomers such as acrylonitrile, halogen-containing monomers such as vinyl chloride, acrylic acid・ Unsaturated carboxylic acids such as methacrylic acid, and other unsaturated dibasic acids ・
Examples thereof include unsaturated dibasic acid anhydrides, polymers such as nitro monomers, copolymers with styrene monomers, polyesters, epoxy resins and the like. In particular, it is preferable to add a polyester resin in order to maintain core / shell formation. The addition amount of these polar polymers / copolymers is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer.

As the coloring agent used in the present invention, known coloring agents can be used, such as carbon black and 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. Mordant 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. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I.
I. Mordant Blue 7, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Dyes such as basic green 6, yellow lead, cadmium yellow, mineral fast yellow, navel yellow, naphthol yellow S, Hansa yellow G, permanent yellow NCG, tartrazine lake, molybdenum orange,
Permanent Orange GTR, Benzidine Orange G,
Cadmium red, permanent red 4R, watching red calcium salt, brilliant carmine 3B,
Fast violet B, methyl violet rake,
Navy blue, cobalt blue, alkali blue rake, Victoria blue rake, quinacridone, rhodamine rake,
Pigments such as phthalocyanine blue, fast sky blue, pigment green B, malachite green lake, and final yellow green G can be used.

When a toner is obtained by the polymerization method in the present invention, it is necessary to pay attention to the polymerization inhibitory property and the water phase transfer property of the colorant, and it is preferable to use surface modification, for example, a substance that does not inhibit the polymerization. It is preferable to apply a hydrophobic treatment. In particular, many dyes and carbon blacks have a polymerization inhibitory property, so care must be taken when using them.

As a preferred method of surface-treating the dye system, there is a method of polymerizing a polymerizable monomer in the presence of these dyes in advance, and a method of adding the obtained colored polymer to the monomer system. To be The carbon black may be treated in the same manner as the above dye, or may be treated with a substance that reacts with the surface functional groups of the carbon black, such as polyorganosiloxane. In the case of a color toner, it is desirable to select and use a colorant from a disazo yellow pigment, a quinacridone magenta pigment, and a phthalocyanine cyan pigment.

A release agent can be used in the toner of the present invention. Examples of the releasing agent include paraffin / polyolefin waxes and modified products thereof, such as oxides and graft-treated products, higher fatty acids, and metal salts thereof, amide waxes, and ester waxes such as tertiary and / or 4 A polyfunctional polyester compound having a secondary carbon and obtained from a difunctional or higher functional alcohol compound or a carboxylic acid compound, a polyfunctional polyester compound having a primary or / and secondary carbon and obtained from a bifunctional or higher functional alcohol compound or carboxylic acid compound Examples thereof include functional polyester compounds and monofunctional ester compounds having tertiary or / and quaternary carbon.

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, among known ones, those having almost no polymerization inhibitory property and water phase migration property are used. For example, as a positive charge control agent, a nigrosine dye, a triphenylmethane dye, a quaternary ammonium salt,
Examples thereof include guanidine derivatives, imidazole derivatives, amine-based and polyamine-based compounds, and negative charge control agents include metal-containing salicylic acid-based compounds, metal-containing monoazo-based dye compounds, urea derivatives, styrene-acrylic acid copolymers,
Examples thereof include styrene-methacrylic acid copolymer. The addition amount of these charge control agents is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

Any suitable polymerization initiator is used as the above-mentioned polymerization initiator, and examples of such a polymerization initiator include 2,2'-azobis- (2,4-dimethylvaleronitrile) and 2,2. '-Azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,
Azo-based or diazo-based polymerization initiators such as 4-dimethylvaleronitrile and azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide,
Examples thereof include peroxide type polymerization initiators such as lauroyl peroxide. These polymerization initiators are preferably added in an amount of 0.5 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer,
You may use together or in combination.

In the present invention, known cross-linking agents and chain transfer agents may be added to control the molecular weight, and the preferable addition amount is 0.001 to 100 parts by weight of the polymerizable monomer. 15 parts by weight.

A dispersion stabilizer for stabilizing the suspension of the monomer composition is preferably used in the aqueous medium used when the toner of the present invention is produced by the polymerization method. As the dispersion stabilizer used in the present invention, various conventionally known dispersion stabilizers can be used. Either or both of an inorganic compound and an organic compound can be used as such a dispersion stabilizer, and examples of the inorganic compound include calcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, Examples thereof include calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica and alumina.

Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and its salt, starch and the like. The dispersion stabilizer can be used by dispersing it in an aqueous phase (aqueous medium).

These dispersion stabilizers are based on the polymerizable monomer 10
It is preferable to use 0.2 to 20 parts by weight with respect to 0 parts by weight. When an inorganic compound is used as the dispersion stabilizer, a commercially available product may be used as it is, but the inorganic compound may be produced in a dispersion medium in order to obtain finer particles. For example, in the case of calcium phosphate, it is advisable to mix the sodium phosphate aqueous solution and the calcium chloride aqueous solution under high stirring.

For fine dispersion of the dispersion stabilizer,
0.001-0.1 parts by weight of surfactant may be used. This is to accelerate 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, stearin. Examples thereof include potassium acidate and calcium oleate.

The toner of the present invention contains an inorganic fine powder in addition to the above-mentioned toner particles. As the inorganic fine powder, as an additive for imparting various toner characteristics, from the viewpoint of durability when included in the toner and when added to the toner, 1/5 of the volume average diameter of the toner particles is used. The following particle diameters are preferable, and more specifically, the average primary particle diameter is 4 to
It is preferably 500 nm. The average primary particle diameter of the inorganic fine powder can be determined by observing the surface of the toner particles with an electron microscope.

If the average primary particle diameter of the inorganic fine powder is smaller than 4 nm, the effect of imparting toner properties by the addition of the inorganic fine powder may not be sufficiently exhibited, and the average primary particle diameter of the inorganic fine powder is larger than 500 nm. In addition, the effect of imparting toner properties by the addition of the inorganic fine powder may not be sufficiently exerted, toner charging inhibition, latent image formation inhibition (exposure inhibition), and coloring of the transfer material by the inorganic fine powder may occur.

Further, it is preferable that the surface of the inorganic fine powder has been subjected to a hydrophobic treatment in order to suppress the fluctuation of the toner characteristics due to the fluctuation of the image forming environment. It is also preferable for suppressing the adhesion of the inorganic fine powder to the surface of the conductive member. Examples of the hydrophobic treatment of the inorganic fine powder include a hydrophobic treatment using a known hydrophobic agent, and examples of the hydrophobic agent include silicone oils and silane coupling agents. Examples thereof include a coating method by spraying a hydrophobizing agent, hydrolysis of a silane coupling agent in an aqueous medium in which an inorganic fine powder is dispersed, and the like.

Many of the inorganic fine powders mainly impart fluidity to the toner, but the toner of the present invention has inorganic fine powders having characteristics other than the above characteristics, organic fine powders having the above characteristics, Further, an organic fine powder having characteristics other than the above characteristics may be further added as an external additive for the toner. Examples of the external additives used in the toner of the present invention are shown below, including the inorganic fine powder.

1) Flowability-imparting agents: metal oxides (silicon oxide, aluminum oxide, titanium oxide, etc.), carbon black, fluorinated carbon, etc. It is more preferable that each is subjected to a hydrophobic treatment. 2) Abrasives: metal oxides (strontium titanate, cerium oxide, aluminum oxide, magnesium oxide, chromium oxide, etc.), nitrides (silicon nitride, etc.), carbides (silicon carbide, etc.), metal salts (calcium sulfate, barium sulfate, etc.) , Calcium carbonate, etc.) etc. 3) Lubricants: Fluorine-based resin powders (vinylidene fluoride, polytetrafluoroethylene, etc.), fatty acid metal salts (zinc stearate, calcium stearate, etc.), etc. 4) Charge control particles: metal oxides (tin oxide, titanium oxide, zinc oxide, silicon oxide, aluminum oxide, etc.),
Carbon black etc.

The total amount of these external additives is 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the toner particles. These external additives may be used alone or in combination. Further, these external additives need not be primary particles and may be aggregates as long as they are in the above-mentioned particle size range.

(3) Conductive Member The conductive member of the present invention is a conductive member which is provided in contact with the above-mentioned charged member to which the toner adheres and charges the charged member. The glass transition temperature of the constituent material is higher than the surface temperature of the member to be charged at the time of contact with the conductive member. Hereinafter, the glass transition temperature (Tg) of the conductive member and the surface temperature (Td) of the member to be charged will be described.

As a result of intensive studies by the inventors, the glass transition temperature Tg of the material of the surface layer of the conductive member and the temperature at the contact surface between the charged member and the conductive member (the surface temperature T of the charged member).
It was found that there is a causal relation between the relationship with d) and the adhesion of the toner and the external additive to the conductive member.

Temperature Td of the contact surface between the member to be charged and the conductive member
Is the glass transition temperature T of the material forming the surface of the conductive member.
If it is higher than g, the surface of the conductive member becomes delicately sticky, so that the transfer residual toner and the external additive easily adhere and become difficult to separate from the surface. Tend to be held in.

For example, in the above-mentioned image forming apparatus, when the member to be charged is the photosensitive member and the conductive member is used as the charging member, the photosensitive member and the conductive member are separated from each other by the temperature rise in the apparatus during the operation of the image forming apparatus. The temperature of the contact surface (drum surface temperature Td) is about 35 to 50 degrees. That is, in order to make it difficult for the transfer residual toner and the external additive to adhere to the surface of the conductive member, the relationship between the glass transition temperature Tg of the material forming the surface of the conductive member and the drum surface temperature Td is Tg> Td. It is important to design

In general, a material having a high glass transition temperature Tg tends to be hard. On the other hand, since the surface layer of the conductive member is in contact with the body to be charged, it should not damage the body to be charged and should not induce fusion of toner on the body to be charged. Therefore, a material that is as soft as possible must be used as the material of the conductive member. Therefore, if Tg> Td is designed as described above, it is very practical without using a material having a higher Tg than necessary.

The thermal property Tg is generally DSC.
Often measured by the method. However, it is difficult to find Tg for a material having a high cross-linking density in which molecular mobility is suppressed. The material forming the surface layer of the conductive member is often a material having a crosslinked structure, and there is a problem that Tg is difficult to obtain. On the other hand, in the present invention, a dynamic viscoelasticity measuring method can be mentioned as a preferable measuring method of Tg. It was found that the dynamic viscoelasticity measurement method is a mechanical measurement, and it is easy to obtain information on the glass transition temperature Tg even with a material having a high crosslink density.

The measuring method of the glass transition temperature Tg in the present invention is to use a measuring apparatus RSA-II "Rheometrics Science FFE Co., Ltd." and to use a film tension fixture as a jig. Is preferred. The temperature dispersion measurement of dynamic viscoelasticity is −
Measurement frequency 6.2 in the temperature range of 50 ° C to 150 ° C
It is preferable to carry out in the auto tension mode of 8 rad / sec, the temperature rising rate of 5 ° C./min, and the initial strain of 0.07% to 0.12%, and the measurement chart as shown in FIG. 5 can be obtained. In the present invention, the glass transition temperature Tg is t
The dispersion peak temperature of an δ was used.

As the measurement sample, a coating solution for forming the surface layer of the conductive member was applied on an aluminum sheet (thickness 0.1 mm), and cured and dried in an oven set to a predetermined temperature for a predetermined time (1 hour). I used one. Also, from these coating films with a cutter knife, 5 mm (W) x 37 mm (L)
The strip-shaped test piece was cut out and used as a measurement sample.

As the surface temperature Td of the member to be charged, the temperature of the contact portion between the conductive member and the member to be charged is known or can be predicted in advance, for example, when the photosensitive member is used as the member to be charged. In some cases known or predicted values can be used,
When unknown or difficult to predict, an actual measurement value measured by a method of measuring the temperature between two objects in contact can be used.

In the case of actual measurement, for example, a method in which a conductive member and a member to be charged, which have a similar structure to the present invention, are operated under the conditions for image formation and the surface temperature of the member to be charged between them is measured in that state Can be illustrated. In the case of actually measuring the surface temperature Td of the charged body, the measuring method is as follows.
For example, use of a digital surface thermometer "HFT-60E manufactured by Anritsu" can be mentioned as a preferable measurement method.

In the conductive member of the present invention, it is preferable that the ten-point average surface roughness Rz of the conductive member is equal to or smaller than the toner particle size. If the ten-point average surface roughness Rz is equal to or smaller than the toner particle size, there is less risk of the toner getting into the irregularities on the surface of the conductive member,
It is preferable for shortening the adhesion time of the toner on the conductive member. When the value of ten-point average surface roughness Rz exceeds the toner particle size, there is a risk that the toner may get into the irregularities on the surface of the conductive member, which is not preferable.

When the conductive member is used as a charging roller and the surface of the conductive member is rough, unevenness of the surface may cause uneven charging, resulting in defective images. Alternatively, the surface of the photoconductor may be eroded (scraped, etc.). Therefore, it is preferable that the surface of the conductive member is smoother, and the ten-point average surface roughness Rz in the JISB0601 surface roughness standard is 10 μm or less, preferably depending on the particle size of the toner used as a preferable range of the value. It is preferably 4 μm or less. The ten-point average surface roughness may be measured by the measuring method defined in the above standard.

In the conductive member of the present invention, the preferred form of the conductive member may change depending on the form of the member to be charged.
For example, a belt shape may be used, but a roller shape is preferable. Hereinafter, the conductive member of the present invention will be described in detail with reference to the preferred embodiments.

As an example of the conductive member of the present invention, as shown in FIG. 2, it is in the shape of a roller, the conductive support 2a, the elastic layer 2b integrally formed on the outer periphery thereof, and the outer periphery of the elastic layer. A conductive member composed of the formed resistance layer 2c and the surface layer 2d further formed on the outer periphery thereof can be exemplified.

Another example of the conductive member of the present invention may be a two-layer structure including an elastic layer 2b and a surface layer 2d as shown in FIG. 3, or a resistance layer 2c as shown in FIG.
The second resistance layer 2e may be provided between the surface layer 2d and the surface layer 2d to form four or more layers on the conductive support.

As the conductive support 2a, a round bar made of a metal material such as iron, copper, stainless steel, aluminum or nickel can be used. Further, these metal surfaces may be subjected to a plating treatment for the purpose of preventing rust and imparting scratch resistance, but it is necessary that the conductivity is not impaired. The form of the conductive support used in the present invention can be selected according to the form of the conductive member. For example, in the case of the belt-shaped conductive member described above, the conductive support may be exemplified by a thin film of aluminum or the like. it can.

The elastic layer used in the present invention is a layer provided for supplying electricity to the body to be charged and ensuring good uniform adhesion of the conductive member to the body to be charged, and having appropriate conductivity and elasticity. . Further, in a roller-shaped conductive member, the elastic layer can be shaped into a so-called crown shape in which the central portion is thickest at the center and becomes thinner toward both ends, so as to ensure uniform adhesion between the conductive member and the member to be charged. It is more preferable to do so.

The charging roller 2 that is generally used applies a predetermined pressing force to both ends of the electroconductive support 2a so that the photoreceptor 1 is
, The pressing force at the central portion is small, and the pressing force at both ends is large. Therefore, there is no problem if the straightness of the charging roller 1 is sufficient, but if it is not sufficient, density unevenness may occur in the image corresponding to the central portion and both end portions. It is even more effective to shape the elastic layer into a crown shape in order to prevent the above situation.

The conductivity of the elastic layer is such that carbon black, conductive metal oxide, alkali metal salt,
1 by adding a conductive agent such as ammonium salt
0 ⁸ good to be adjusted to less than [Omega] cm.

The elasticity and hardness of the elastic layer are adjusted by adding a softening oil, a plasticizer or the like and foaming the resin. Specific elastic materials for the elastic layer include, for example, natural rubber, EPDM, SBR, silicone rubber, urethane rubber, epichlorohydrin rubber, IR, BR, NBR, and C.
Other examples include synthetic rubbers such as R, polyamide resin, polyurethane resin, and silicone resin. A foam obtained by foam-molding these elastic materials may be used for the elastic layer.

The resistance layer is formed at a position in contact with the elastic layer, and is provided as necessary for the purpose of preventing bleeding out of the softening oil, the plasticizer or the like contained in the elastic layer to the surface of the conductive member. . Examples of the material forming the resistance layer used in the present invention include epichlorohydrin rubber, NBR,
Urethane rubber, polyolefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, fluororubber-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, polybutadiene-based thermoplastic elastomer, ethylene vinyl acetate-based Examples thereof include thermoplastic elastomers, polyvinyl chloride-based thermoplastic elastomers and chlorinated polyethylene-based thermoplastic elastomers. These materials may be used alone or in combination of two or more, and may be a copolymer.

The resistance layer used in the present invention must have conductivity or semiconductivity. Various conductive agents (conductive carbon, conductive tin oxide, conductive titanium oxide, copper, aluminum, nickel, iron powder, alkali metal salts, ammonium salts, etc.) are appropriately used to develop conductivity and semiconductivity. Can be used. In this case, in order to obtain a desired electric resistance, two or more kinds of the various conductive agents may be used in combination.

The surface layer constitutes the surface of the conductive member that contacts the member to be charged. Therefore, as described above, the glass transition temperature (T) higher than the surface temperature (Td) of the body to be charged.
It is necessary to be composed of the material of g), and it is preferable that the material structure does not or does not easily contaminate the charged body by contact.

As the binder resin material for the surface layer used in the present invention, fluororesin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, styrene-ethylene / butylene-olefin copolymer (SEBC), Examples include olefin-ethylene / butylene-olefin copolymer (CEBC). When using these binder resin materials, when Tg is unknown, or when a plurality of types are used in combination or when a copolymer is used, the test piece introduced in the above-mentioned measurement of Tg is produced,
The binder resin material to be used can be selected by actually measuring Tg.

Various conductive agents (conductive carbon, conductive tin oxide, conductive titanium oxide, copper, aluminum, nickel, etc.) can be appropriately used for the surface layer. In this case, in order to obtain a desired electric resistance, two or more kinds of the various conductive agents may be used in combination.

The above-mentioned layers may be formed by a conventionally known layer forming technique so as to have an appropriate layer thickness according to their respective roles.

The conductive member of the present invention is preferably used as a charging member for charging a photoconductor as a member to be charged, as shown in the above-mentioned image forming apparatus, but in addition, the member to be charged to which toner adheres is also charged. It can be used in various cases as a member for contacting and charging the body. As such a case, the above-mentioned charging roller 2, a pre-transfer charger for charging the toner image before transfer to make the potential of the toner uniform, and a roll-shaped or belt-shaped intermediate transfer member as the sub-transfer means. When used, a charging member for an intermediate transfer member that charges the intermediate transfer member can be exemplified.
The conductive member of the present invention has a shape and
The physical properties such as glass transition temperature, ten-point average surface roughness, and volume resistance may be set appropriately. Hereinafter, the present invention will be described in more detail with reference to examples.

[0102]

EXAMPLES Example 1 A conductive member of the present invention was produced in the following manner. Epichlorohydrin rubber (terpolymer) 100 parts by weight Light calcium carbonate 30 parts by weight Plasticizer (molecular weight 4000) 10 parts by weight Stearic acid 1 part by weight Anti-aging agent MB 0.5 parts by weight Zinc oxide 5 parts by weight Quaternary ammonium salt 3 parts by weight

The above materials are kneaded for 10 minutes in a closed mixer adjusted to 45 ° C. to adjust the raw material compound. 1 part by weight of sulfur as a vulcanizing agent was added to 100 parts by weight of epichlorohydrin rubber as a raw material rubber,
1 part by weight of DM (dibenzothiazyl disulfide) as a vulcanization accelerator and 0.5 part by weight of TS (tetramethylthiuram monosulfide) were added, and the mixture was kneaded for 10 minutes with a two-roll machine cooled to 20 ° C. . The obtained compound is molded around a Φ6 mm stainless steel core metal by an extrusion molding machine so as to have a roller shape with an outer diameter of 15 mm, vulcanized by heating steam, and then polished to an outer diameter of 12 mm. The elastic layer was obtained. A surface layer shown below was formed by coating on the elastic layer.

The following materials were mixed as materials for the surface layer. Caprolactone modified acrylic polyol solution 100 parts by weight (solid content 20% by mass, solvent: MEK (methyl ethyl ketone)) conductive tin oxide 20 parts by weight

This mixed solution was mixed with glass beads (average particle diameter φ
1 mm) was used as the dispersion medium and dispersed for 5 hours using a vertical sand mill. Then, hexamethylene diisocyanate (H
DI), (caprolactone-modified acrylic polyol solution: HD
I) = (70:10) so that the ratio (weight ratio) was adjusted and the surface layer coating material was adjusted. The surface of the elastic layer of the elastic roller was coated with the surface layer coating material by a dipping method, and then dried in a hot air circulation dryer at a temperature of 150 ° C. for 1 hour. The thickness of the surface layer after drying was 21 μm.

"Measurement of glass transition temperature Tg of surface layer" Using a measuring device RSA-II "Rheometrics Science FFE Co., Ltd.", the dispersion of the glass transition temperature Tg (tan δ was measured as described above. The peak temperature was measured. The glass transition temperature Tg of the conductive member of this example was 46 ° C.

[Measurement of Surface Roughness Rz of Conductive Member] Co., Ltd.
The measurement was performed using a surface roughness measuring device SE-3400 manufactured by Kosaka Laboratory. The ten-point average surface roughness Rz on the surface of the conductive member in this example was 2.1 μm.

"Continuous multiple image output durability test" The above electroconductive member was attached as a charging roller to the electrophotographic image forming apparatus shown in FIG. 1, and the environment 1 (temperature 23 ° C., humidity 55%), environment 2 (Temperature 32.5 ° C, Humidity 80%), Environment 3 (Temperature 15 ° C, Humidity 10%)
A durability test was conducted on a plurality of images. By visually observing the obtained image, the toner adhered on the charging roller, and the occurrence of fogging on the printing paper caused by the toner was evaluated.

As the toner, a spherical toner (particle size: 7 μm) produced by the above-mentioned suspension polymerization method was used. As the external additive, silica particles having a hydrophobic surface (particle size 12
nm) and hydrotalcite-based compound particles (untreated surface, particle size 450 nm).

The surface temperature Td of the photosensitive drum during the operation of continuously outputting a plurality of images under each environment was the following value. Environment 1: 40 ° C Environment 2: 44 ° C Environment 3: 35 ° C

The results are shown in Table 1. In the table, ⊚ indicates that the obtained image is very good, ○ indicates that it is good, Δ indicates that the halftone image has a slight image fog, and × indicates that the halftone image has a clear fog in the rotation cycle of the charging roller. Indicates that. As a result, in this example, a good image was obtained from the initial stage under all environments, and an image which was almost the same as the initial stage was obtained even after outputting 15,000 images.

“Evaluation of Image Fogging by Adhering Toner and External Additive on Charging Roller” After the above “continuous multiple image output durability test”, the image forming apparatus was left in the environment 3 for 24 hours to evaluate the image output. I went. By visually observing the obtained image, the occurrence of fogging on the printing paper due to the adhesion of toner on the charging roller and the evaluation thereof was evaluated.

Under the environment 3, the influence of image fog 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 image fog evaluation after performing a continuous multiple image output durability test in each environment.

The results are shown in Table 1. In the table, ⊚ indicates that the obtained image is very good, ○ indicates that it is good, Δ indicates that the halftone image has a slight image fog, and × indicates that the halftone image has a clear fog in the rotation cycle of the charging roller. Indicates that. In this example, an image substantially equivalent to that at the time of outputting 15,000 sheets was obtained.

[0115]

[Table 1]

Example 2 In this example, as a material for the surface layer, 100 parts by weight of a caprolactone-modified acrylic polyol solution (solid content 20% by mass, solvent: MEK) conductive tin oxide 20 parts by weight Silicone oil solution 2 parts by weight Part (silicone oil 1% by mass, solvent: MEK), hexamethylene diisocyanate (HDI)
(Caprolactone-modified acrylic polyol solution: HD
I) = (70:20), the coating for the surface layer was adjusted, and the thickness of the surface layer after drying was 20 μm.

The glass transition temperature Tg of the conductive member in this example was 60 ° C. The ten-point average surface roughness Rz on the surface of the conductive member was 1.1 μm. Table 1 shows the results of the continuous image output durability test and the image fog evaluation test after image output in this example. As can be seen from Table 1, in this example, good images equivalent to or higher than those in Example 1 could be obtained in both the durability test and the image fog evaluation test.

(Example 3) In this example, hexamethylene diisocyanate (HDI) was added to (caprolactone-modified acrylic polyol solution: HD
I) = (70:30), the surface layer coating material was adjusted, and the thickness of the surface layer after drying was 18 μm.

The glass transition temperature Tg of the conductive member in this example was 72 ° C. The ten-point average surface roughness Rz on the surface of the conductive member was 1.3 μm. Table 1 shows the results of the continuous image output durability test and the image fog evaluation test after image output in this example. As can be seen from Table 1, in this example, good images equivalent to those in Example 1 could be obtained in both the durability test and the image fog evaluation test.

Example 4 In this example, as a material for the surface layer, 100 parts by weight of a caprolactone-modified acrylic polyol solution (solid content 20% by mass, solvent: MEK) conductive tin oxide 20 parts by weight Silicone oil solution 2 parts by weight Part (silicone oil 1% by mass, solvent: MEK), the hexamethylene diisocyanate (HDI) is replaced by an isocyanate represented by the following formula (1): (caprolactone-modified acrylic polyol solution: isocyanate of the following formula (1)) = In the same manner as in Example 1, except that the coating material for the surface layer was adjusted so that the ratio was (70: 15.2), and the thickness of the surface layer after drying was 20 μm.

[0121]

[Chemical 1]

The glass transition temperature Tg of the conductive member in this example was 58 ° C. The ten-point average surface roughness Rz on the surface of the conductive member was 1.5 μm. Table 1 shows the results of the continuous image output durability test and the image fog evaluation test after image output in this example. As can be seen from Table 1, in this example, good images equivalent to or higher than those in Example 1 could be obtained in both the durability test and the image fog evaluation test.

(Embodiment 5) This embodiment is the same as Embodiment 1 except that silica particles whose surface is hydrophobized and hydrotalcite compound particles (surface-treated product) are used as external additives for the toner. I went the same way. Table 1 shows the results of the continuous image output durability test and the image fog evaluation test after image output in this example. In this example, good images equivalent to or higher than those in Example 1 could be obtained in both the durability test and the image fog evaluation test. Particularly, in the present embodiment, the level of image fog was improved as compared with the first embodiment. It is considered that this is due to the effect of surface-treating the particles of the hydrotalcite compound used as a part of the external additive.

(Example 6) This example is the same as Example 1 except that silica particles whose surfaces were hydrophobized and titanium oxide particles (untreated surface / average particle size 300 nm) were used as external additives for the toner. The same procedure as 1 was performed. Table 1 shows the results of the continuous image output durability test and the image fog evaluation test after image output in this example. In this example, an image substantially equivalent to that in Example 1 could be obtained in both the durability test and the image fog evaluation test.

(Comparative Example 1) In this comparative example, hexamethylene diisocyanate (HDI) was used (caprolactone-modified acrylic polyol solution: HD
I) = (70: 5), the coating material for the surface layer was adjusted, and the thickness of the surface layer after drying was 22 μm to obtain a conductive member in the same manner as in Example 1. The glass transition temperature Tg of the conductive member of this comparative example was 34 ° C. The ten-point average surface roughness Rz of the surface of the conductive member was 3.7 μm.

In this comparative example, the above-mentioned conductive member was used as a charging roller, and styrene / methyl /
The same procedure as in Example 1 was carried out except that methacrylate (untreated surface / average particle size 50 nm) was used. Table 1 shows the results of the continuous image output durability test and the image fog evaluation test after image output in this comparative example. As can be seen from Table 1, in the comparative example, in the plural-image image output durability test under each environment, image fog caused by the toner and the external additive adhering to the surface of the charging roller occurred in the latter half of the durability test.

[0127]

As can be seen from the above description, according to the present invention, a toner containing toner particles and an inorganic fine powder is used, and the glass transition temperature of the material forming the surface is the surface of the photoreceptor at the time of image formation. Since the charging member designed to be higher than the temperature is used, the toner and the external additive are less adhered to the surface of the charging member, so that the image fog and the image density unevenness caused by the adhesion do not occur. As a result, even when the developing / cleaning method (cleanerless method) is adopted, the total number of printed sheets of the image forming apparatus is significantly increased, and durability stability is improved. Further, even in an environment of low temperature and low humidity, image fog caused by adhesion of toner and external additives does not occur.

Further, according to the present invention, when the glass transition temperature is the dispersion peak temperature of tan δ in the dynamic viscoelasticity measurement, it is more effective in easily determining the glass transition temperature of the surface of the charging member.

Further, according to the present invention, when the developing means also serves as a means for collecting the toner remaining on the photoconductor after the transfer, further downsizing of the image forming apparatus and prevention of generation of waste toner are realized. Is more effective in doing.

Further, according to the present invention, the image forming apparatus is a process cartridge having at least a photoconductor and a developing means, and the components are integrated and detachable from the main body of the image forming apparatus. It is even more effective in making maintenance easier.

According to the present invention, it is more effective to use an inorganic fine powder having an average primary particle diameter of 4 to 500 nm in the above toner from the viewpoint of imparting characteristics to the toner or promoting characteristics thereof, and the surface is subjected to a hydrophobic treatment. It is more effective to use the finely divided inorganic powder to suppress the characteristic fluctuation of the toner due to environmental fluctuation, and it is more effective to form a high quality image by using a spherical toner by the polymerization method. Is.

Further, according to the present invention, it is possible to provide a conductive member in which the glass transition temperature of the material constituting the surface is designed to be higher than the surface temperature of the member to be charged. In addition to the above relationship, the above-described effects are exhibited by using the various contact charging members in which the toner may be attached.

Further, according to the present invention, when the ten-point average surface roughness of the conductive member is equal to or smaller than the toner particle size, the toner does not adhere to the conductive member, or even if it adheres, the residence time of the toner becomes shorter. As a result, toner fusion does not easily occur, and it is even more effective in uniformly and favorably charging the charged body.

Further, according to the present invention, forming the conductive member in the shape of a roller is more effective in utilizing it as various contact charging members in the image forming apparatus.

[Brief description of drawings]

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

FIG. 2 is a schematic view showing an example of a conductive member of the present invention.

FIG. 3 is a schematic view showing another example of the conductive member of the present invention.

FIG. 4 is a schematic view showing another example of the conductive member of the present invention.

FIG. 5 is a measurement chart obtained when the glass transition temperature (Tg) on the surface of the conductive member of the present invention is measured by a dynamic viscoelasticity measuring device.

[Explanation of symbols]

1 photoconductor 2 Charging roller (charging member) 2a conductive support 2b elastic layer 2c, 2e resistance layer 2d surface layer 3 exposure means 4 developing means 4a toner carrier 4b Supply roller 4c Toner layer thickness regulating member 5 Transfer roller S1 Charging bias application power supply S2 Transfer bias application power supply P transfer material

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/08 507 G03G 15/08 507L 21/10 21/00 312 312/08/08 384 (72) Inventor Nagata Hiroyuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Seiji Tsuru 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Satoshi Taniguchi Tokyo Ohta 3-30-2 Shimomaruko-ku, Canon Inc. (72) Inventor Kazuyuki Miyano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2H005 AA08 AA15 AB06 CB12 CB13 DA05 EA05 2H077 AA37 AC16 AD02 AD06 AD13 AD31 EA14 2H134 GA01 GB02 HF13 JA11 KG01 KG03 KG07 KH03 KH10 KH11 2H200 FA01 FA02 FA12 FA13 FA14 GA14 GA16 GA18 GA23 GA34 GA46 GA59 GB32 GB 37 HA02 HB12 HB22 HB43 HB45 HB46 HB47 HB48 JA02 MA03 MA04 MA08 MA12 MA14 MA20 MB01 MC01 MC06 MC10 MC20 NA02 NA06

Claims (13)

[Claims] 1. A charging unit having a photosensitive member and a conductive charging member provided in contact with the photosensitive member to charge the photosensitive member by applying a voltage to the charging member, and exposing the charged photosensitive member to light. An exposure unit that forms an electrostatic latent image on the photoconductor, a developing unit that forms a toner image on the photoconductor on which the electrostatic latent image is formed, and a transfer unit that transfers the toner image on the photoconductor onto a transfer material. In the image forming apparatus, the toner forming the toner image contains toner particles and inorganic fine powder, and the glass transition temperature of the material forming the surface of the charging member is the surface temperature of the photoconductor during image formation. Image forming apparatus characterized by being higher than. 2. The image forming apparatus according to claim 1, wherein the glass transition temperature is a dispersion peak temperature of tan δ in dynamic viscoelasticity measurement. 3. The image forming apparatus according to claim 1, wherein the developing unit also serves as a unit for collecting the toner remaining on the photoconductor after transfer. 4. The image forming apparatus according to claim 1, wherein the image forming apparatus has at least the photoconductor and the developing unit, the constituent elements are integrated, and the image forming apparatus main body is provided. A process cartridge characterized in that it is configured to be removable. 5. A charging unit having a photosensitive member and a conductive charging member provided in contact with the photosensitive member to charge the photosensitive member by applying a voltage to the charging member, and exposing the charged photosensitive member to light. An exposure unit that forms an electrostatic latent image on the photoconductor, a developing unit that forms a toner image on the photoconductor on which the electrostatic latent image is formed, and a transfer unit that transfers the toner image on the photoconductor onto a transfer material. Have,
A toner that is used in an image forming apparatus in which the glass transition temperature of the material forming the surface of the charging member is higher than the surface temperature of the photoconductor during image formation, and is a toner that forms the toner image, including toner particles and inorganic fine powder. A toner containing: 6. The toner has an average primary particle diameter of 4 to 500.
nm inorganic fine powder is contained.
The toner according to. 7. The toner according to claim 5, wherein the toner is a toner containing an inorganic fine powder whose surface is hydrophobized. 8. The toner according to claim 5, wherein the toner is a toner produced by a polymerization method and has a spherical shape. 9. A conductive member, which is provided in contact with the charged body to which the toner according to claim 5 is attached, for charging the charged body, comprising: a material forming a surface of the conductive member. A conductive member having a glass transition temperature higher than a surface temperature of the charged body at the time of contact with the conductive member. 10. The conductive member according to claim 9, wherein the glass transition temperature is a dispersion peak temperature of tan δ in dynamic viscoelasticity measurement. 11. The ten-point average surface roughness of the conductive member is less than or equal to the toner particle size.
The conductive member according to. 12. The conductive member according to claim 9, wherein the conductive member has a roller shape. 13. The conductive member is a charging member in the image forming apparatus according to claim 1, and the charged body is the image according to any one of claims 1 to 3. The conductive member according to any one of claims 9 to 12, which is a photoconductor in a forming apparatus.