JP2010151962A - Image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which suppresses minute color streaks parallel to an axis direction of a charging roller in a formed image. <P>SOLUTION: The image forming apparatus has an image holding body and the charging roller which has at least an elastic layer 206 on a core body 204 and in which a front face of a surface is reformed and resistance unevenness is reduced by applying ultraviolet exposure processing to a surface of the elastic layer or a surface of a surface layer 208 and which rotates while contacting the image holding body and charges the image holding body only with a DC voltage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a process cartridge.

  In recent years, image forming apparatuses such as printers and copiers have been widely used, and technologies relating to various elements constituting the image forming apparatus have also been widely used. Among image forming apparatuses that employ an electrophotographic method, a photosensitive member such as a photosensitive member (image holding member) drum is charged by using a charging device, and an ambient potential is applied on the charged photosensitive member. In many cases, a pattern to be printed is formed by forming an electrostatic latent image having a potential different from that of the electrostatic latent image. The electrostatic latent image formed in this way is developed with toner, and finally recorded. It is transferred onto a recording medium such as paper.

  The charging device is an apparatus that performs an important function of charging the photosensitive member. A contact charging type charging device (for example, a charging roller) that directly contacts the photosensitive member to charge the photosensitive member, and the photosensitive member are: There are roughly classified into two types of charging devices such as a non-contact charging device (for example, a scorotron charger) that charges the photosensitive member by corona discharge or the like in the vicinity of the photosensitive member without contact. In recent years, there has been an increase in charging devices that employ a contact charging method that generates less chemical substances such as ozone and nitrogen oxides than non-contact charging devices.

Various studies have been made on the charging roller used in the contact charging method.
For example, for the purpose of reducing the friction coefficient, a technique is known in which a surface layer of a charging roller has a polyurethane resin and the surface layer is irradiated with ultraviolet rays (see, for example, Patent Document 1). In addition, for the purpose of suppressing bleeding from the charging roller to the photoconductor (contamination of the photoconductor by the charging roller), a technique for irradiating the surface of the charging roller with ultraviolet rays or the like is known (see, for example, Patent Documents 2 to 5). ).
JP-A-9-160353 JP-A-9-160355 Japanese Patent Laid-Open No. 11-084819 Japanese Patent Laid-Open No. 11-194583 JP 2002-357215 A

  It is an object of the present invention to provide an image forming apparatus and a process cartridge in which color streaks in a formed image are suppressed.

The above problem is solved by the following means. That is,
The invention according to claim 1
An image carrier,
A charging roller having at least an elastic layer on the core, the surface being subjected to ultraviolet irradiation treatment, rotating in contact with the image carrier and charging the image carrier only with a DC voltage;
An image forming apparatus.

The invention according to claim 2
The image forming apparatus according to claim 1, wherein the image carrier has a photosensitive layer having a thickness of 20 μm to 40 μm on a conductive support.

The invention according to claim 3
The image forming apparatus according to claim 1, wherein the charging roller further has a surface layer on the elastic layer.

The invention according to claim 4
The image forming apparatus according to claim 1, wherein the charging roller charges the image holding member to a potential of −100 V or less.

The invention according to claim 5
Furthermore, latent image forming means for forming a latent image on the surface of the image carrier charged by the charging roller, and development for forming a toner image by developing the latent image formed on the surface of the image carrier with toner. Means,
5. The image forming apparatus according to claim 1, wherein an absolute value of a difference between the potential of the image holding member charged by the charging roller and the potential of the developing unit is 30 V or less. .

The invention according to claim 6
An image carrier,
A charging roller having at least an elastic layer on the core, the surface being subjected to ultraviolet irradiation treatment, rotating in contact with the image carrier and charging the image carrier only with a DC voltage;
A process cartridge.

The invention according to claim 7 provides:
The process cartridge according to claim 6, wherein the image carrier has a photosensitive layer having a thickness of 20 μm to 40 μm on a conductive support.

The invention according to claim 8 provides:
The process cartridge according to claim 6, wherein the charging roller further has a surface layer on the elastic layer.

The invention according to claim 9 is:
The process cartridge according to any one of claims 6 to 8, wherein the charging roller charges the image carrier to a potential of -100V or less.

The invention according to claim 10 is:
Furthermore, latent image forming means for forming a latent image on the surface of the image carrier charged by the charging roller, and development for forming a toner image by developing the latent image formed on the surface of the image carrier with toner. Means,
The process cartridge according to any one of claims 6 to 9, wherein an absolute value of a difference between a charging potential of the image holding member by the charging roller and a developing potential of the developing unit is 30 V or less.

According to the first aspect of the present invention, there is provided an image forming apparatus in which color streaks in the formed image are suppressed as compared with the case where the surface of the charging roller is not irradiated with ultraviolet rays.
According to the second aspect of the present invention, there is provided an image forming apparatus in which the color streaks in the formed image are suppressed and the service life is long as compared with the case where the film thickness of the photosensitive layer is not taken into consideration.
According to the invention of claim 3, image formation in which color streaks in the formed image are suppressed and contamination of the charging roller is suppressed as compared with the case where no further surface layer is provided on the elastic layer. An apparatus is provided.
According to the fourth aspect of the present invention, there is provided an image forming apparatus in which the color streaks in the formed image are suppressed as compared with the case where the charged potential of the image carrier is not taken into consideration.
According to the invention of claim 5, in the formed image, compared with the case where the absolute value of the difference between the potential of the image carrier charged by the charging roller and the potential of the developing unit is not taken into consideration. An image forming apparatus in which color lines are suppressed is provided.
According to the invention which concerns on Claim 6, compared with the case where the charging roller surface is not irradiated with ultraviolet rays, the process cartridge in which the color stripe in the formed image was suppressed is provided.
According to the seventh aspect of the present invention, there is provided a process cartridge in which color streaks in the formed image are suppressed and the service life is long as compared with the case where the film thickness of the photosensitive layer is not taken into consideration.
According to the eighth aspect of the present invention, there is provided a process cartridge in which color streaks in the formed image are suppressed and contamination of the charging roller is suppressed as compared with a case where no further surface layer is provided on the elastic layer. Is done.
According to the ninth aspect of the present invention, there is provided a process cartridge in which color streaks in the formed image are suppressed as compared with a case where the charged potential of the image carrier is not taken into consideration.
According to the invention of claim 10, in the formed image, compared with the case where the absolute value of the difference between the potential of the image carrier charged by the charging roller and the potential of the developing unit is not considered. A process cartridge with suppressed color streaks is provided.

Hereinafter, embodiments of the present invention will be described.
The image forming apparatus according to the present embodiment has an image carrier and at least an elastic layer on the core, the surface is subjected to ultraviolet irradiation treatment, rotates in contact with the image carrier and rotates the image carrier. And a charging roller for charging only with a DC voltage.
The process cartridge according to the present embodiment is, for example, a cartridge that is detachable from the image forming apparatus main body, has an image holding body, and at least an elastic layer on the core body, and has a surface subjected to ultraviolet irradiation treatment. A charging roller that rotates in contact with the image carrier and charges the image carrier only with a DC voltage.

In general, a contact charging type charging device using a charging roller includes a DC charging method for charging an image carrier using only a direct current voltage (DC) without using an alternating current voltage (AC), and an alternating current voltage applied to the direct current voltage. There are two types of AC / DC charging methods that are superposed and charged. Here, the DC charging method has the advantage that the photosensitive layer of the image carrier is less worn and consumes less power than the AC / DC charging method.
However, in the DC charging method, a color streak (a minute streak-like unevenness having a width of about 1 mm and a length of about 1 mm to about 100 mm) is formed on an image to be formed. May occur.
Therefore, by adopting the configuration of the present embodiment for the image forming apparatus or the process cartridge, color streaks in the formed image are suppressed in the DC charging method.

The details of the cause of the above effect are unknown, but the following causes are presumed. However, this embodiment is not limited to the following causes.
That is, generally, when an energy higher than the molecular bond (for example, ultraviolet rays) is given to the organic compound, the bond is broken. When the C—H molecule is broken, the hydrogen atom is very light and can be easily extracted. When oxygen atoms react there, for example, oxygen-rich functional groups are formed. That is, surface modification occurs.
On the other hand, for the surface layer of the charging roller, the dispersion liquid of the surface layer material is applied by various application methods and the dispersion solvent is removed by various methods such as heating. At this time, the surface layer material is localized, and it is considered that local resistance unevenness occurs due to the localized points. In addition, in the case of a charging roller having only an elastic layer without a surface layer, the material is localized during kneading and molding of the elastic material. It is considered that resistance unevenness occurs. Then, it is presumed that color streaks occur in the formed image due to these local resistance irregularities.
Therefore, since the surface is modified as described above by irradiating the charging roller with ultraviolet rays, the entire surface including the localized point is modified even if there is a localized point of the material in the charging roller. It is considered to be quality. As a result, it is presumed that local resistance unevenness on the surface of the charging roller is reduced and generation of color stripes is suppressed.

FIG. 1 is a schematic diagram of an image forming apparatus according to the present embodiment.
An image forming apparatus 110 shown in FIG. 1 includes a photosensitive drum 30 (hereinafter also referred to as an “electrophotographic photosensitive member”) 30 provided to rotate as an image holding member. Around the photosensitive drum 30, along the movement direction of the outer peripheral surface of the photosensitive drum 30, the charging roller 31, the exposure device 33, the developing device 34, the transfer device 35, the cleaning device 36, and the charge eliminating device (erase device). 37 are arranged in this order. Further, the image forming apparatus 110 includes a fixing device 38 that fixes the toner image on the transfer medium after the transfer process.

The charging roller 31 is connected to a power source 32.
The charging roller 31 rotates in a state where the surface is in contact with the surface of the photosensitive drum 30, and charges the photosensitive drum 30 to a predetermined charging potential only by a DC voltage without using an AC voltage. The charging roller 31 is produced by subjecting the surface to ultraviolet irradiation treatment. A preferred form of the charging roller will be described later.

  The exposure device 33 exposes the charged photosensitive drum 30 to form an electrostatic latent image on the surface of the photosensitive drum 30.

The developing device 34 develops the electrostatic latent image with toner to form a toner image.
The developing device 34 has a known configuration including, for example, a developer containing toner (and carrier if necessary) and a developing roll for attaching the toner to the image holding member in a housing.
The developing device in the present embodiment includes, for example, a developer containing toner, and a developing roll (for example, a circular member in the developing device 34 in FIG. 1) for attaching the toner to the image holding member. This is a known configuration. If necessary, a blade for removing the toner excessively attached to the developing roll may be provided.

The developer preferably contains a toner having a volume average particle diameter of 3 μm or more and 9 μm or less obtained by a polymerization method.
The transfer device 35 transfers the toner image developed on the photosensitive drum 30 to a transfer medium.

The cleaning device 36 removes the toner remaining on the photosensitive drum 30 after the transfer. The cleaning device 36 preferably has a blade member that contacts the photosensitive drum 30 at a linear pressure of 10 g / cm to 150 g / cm.
The static eliminator (erase device) 37 erases the remaining charges on the photosensitive drum 30.

  Although not shown, a charging member cleaning device for cleaning the charging device 31 may be provided. By providing this charging member cleaning device, foreign substances that can cause resistance unevenness of the charging device 31 such as paper dust, toner, and discharge products due to long-term use can be efficiently removed.

  In FIG. 1, the image forming apparatus 110 has a configuration in which the photosensitive drum 30, the charging roll 31, and the like are directly incorporated in the image forming apparatus 110. However, the present embodiment is not limited to this configuration. For example, a process cartridge including the photosensitive drum 30 and the charging roll 31 may be incorporated in the image forming apparatus 110.

  The configurations of the photosensitive drum 30, the charging roller 31, the exposure device 33, the developing device 34, the transfer device 35, the cleaning device 36, and the fixing device 38 in FIG. 1 are shown in FIG. The photosensitive drum 52, the charging roller 53, the exposure device 54, the developing device (55Y, 55M, 55C, or 55K), the transfer device 22, the cleaning device 80, and the fixing device 64 may be used.

FIG. 2 is a schematic diagram of an image forming apparatus according to another embodiment.
The image forming apparatus 50 shown in FIG. 2 is a tandem full-color printer.
Inside the image forming apparatus 50, a photosensitive drum (electrophotographic photosensitive member) 52 as an image holding member, a charging roller 53, a roller-shaped cleaning member 100, a cleaning device 80, and a developing device (55Y, 55M, 55C, or 55K). ) And the like are provided for each color of yellow (51Y), magenta (51M), cyan (51C), and black (51K).
Here, the photosensitive drum (electrophotographic photosensitive member) 52, the charging roller 53, the roller-shaped cleaning member 100, the cleaning device 80, and the developing device (55Y, 55M, 55C, or 55K) are provided in the form of a process cartridge. The image forming apparatus 50 may be directly provided inside the image forming apparatus 50.

  As the photosensitive drum 52, for example, a conductive cylinder having a diameter of 25 mm and having a surface coated with an organic photosensitive layer is used, and is rotated by a motor (not shown) at a process speed of, for example, 150 mm / sec.

In this embodiment, “conductive” refers to the property of having a volume resistivity of less than 10 ¹³ Ω · cm, and “insulating” refers to the property of having a volume resistivity of 10 ¹³ Ω · cm or more. Point to.

The surface of the photosensitive drum 52 is charged to a predetermined charging potential by a charging roller 53 disposed so that the surface of the photosensitive drum 52 is in contact with the surface of the photosensitive drum 52. The charged surface of the photosensitive drum 52 is subjected to image exposure by a laser beam emitted from the exposure device 54, and an electrostatic latent image corresponding to image information is formed.
The electrostatic latent image formed on the photosensitive drum 52 is developed by developing devices 55Y, 55M, 55C, and 55K for yellow (Y), magenta (M), cyan (C), and black (K). A toner image is obtained.

  For example, when a full-color image is formed, the charging, exposure, and development processes are performed on the surface of the photosensitive drum 52 of each color by yellow (Y), magenta (M), cyan (C), and black (K). A toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the surface of the photosensitive drum 52 of each color. .

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drum 52 are conveyed on the sheet conveying belt 56 by the transfer unit 22. It is transferred onto a recording paper (transfer object) 57 (transfer process). The paper transport belt 56 is stretched by rolls 40 and 42. The recording paper 57 is transported from the paper supply unit 28 to the paper transport belt 56 by the feed roll 10 and the pair of rolls 12 and 14. Specifically, as the transfer device, for example, a charged toner particle is formed by creating an electric field between the image carrier and the recording paper using a conductive roller, brush, film, rubber blade or the like to which voltage is applied. The toner image formed by the charged toner particles is transferred by corona charging the back surface of the recording paper with a means for transferring the toner image formed in step 1 or a corotron charger or scorotron charger using corona discharge. Conventionally known means such as means are used.

  Further, the recording paper 57 onto which the toner image has been transferred from the paper conveying belt 56 is conveyed to the fixing device 64, and is heated and pressed by the fixing device 64 to fix the toner image on the recording paper 57. Thereafter, in the case of single-sided printing, the recording paper 57 on which the toner image is fixed is discharged as it is onto a discharge unit 68 provided at the top of the image forming apparatus 50 by a discharge roll 66.

On the other hand, in the case of double-sided printing, the recording paper 57 on which the toner image is fixed on the first surface (front surface) by the fixing device 64 is not directly discharged onto the discharge portion 68 by the discharge roll 66 but is discharged as it is. With the rear end of the recording paper 57 held between the two, the discharge roller 66 is reversed, the conveyance path of the recording paper 57 is switched to the double-sided paper conveyance path 70, and the double-sided paper conveyance path 70 is arranged. With the conveyance roller 72 provided, the recording sheet 57 is reversed and conveyed to the secondary transfer position of the sheet conveyance belt 56, and the toner image is transferred to the second surface (back surface) of the recording sheet 57. To do. Then, the toner image on the second surface (back surface) of the recording paper 57 is fixed by the fixing device 64, and the recording medium 57 is discharged onto the discharge portion 68.
Note that the surface of the photosensitive drum 52 after the toner image transfer process is completed is arranged such that the end of the surface of the photosensitive drum 52 contacts the photosensitive drum 52 every time the photosensitive drum 52 rotates (cleaning). Blade) 80 removes residual toner, paper dust, and the like, and prepares for the next image forming process. The charging roller 53 is cleaned by the roller-like cleaning member 100 that rotates following the charging roller 53 during operation of the image forming apparatus.

Next, details of the charging roller (for example, the charging roller 31 and the charging roller 53) in the present embodiment will be described with reference to FIG. 3, but the present embodiment is not limited to this.
FIG. 3 is a schematic perspective view of the charging roller in the present embodiment.
As shown in FIG. 3, the charging roller 200 includes an elastic layer 206 (hereinafter referred to as “conductive elastic layer”) as a charging layer on a conductive shaft 204 that is a core (that is, on the outer peripheral surface of the shaft 204). And a surface layer 208 on the elastic layer 206 (that is, on the outer peripheral surface of the elastic layer 206). In the following description, the charging roller may be referred to as a “conductive elastic roller”.

Here, the surface layer 208 may be omitted from the viewpoint of productivity and cost, but from the viewpoint of preventing contamination of the charging roller, the surface layer 208 is preferably provided.
In addition, the charging roller according to the present embodiment is not limited to the above-described configuration. For example, the charging roller is provided between the elastic layer 206 and the shaft 204, and between the elastic layer 206 and the surface layer 208. It is also possible to provide a resistance adjusting layer or migration preventing layer, and a coating layer (protective layer) disposed on the outer side (outermost surface) of the surface layer 208.

The charging roller in the present embodiment is produced by irradiating the surface with ultraviolet rays, regardless of whether or not it has a surface layer. Here, the “surface” of the charging roller is the surface of the elastic layer when only the elastic layer is provided on the shaft, and the surface of the surface layer when the surface layer is further provided on the elastic layer. is there. Preferred conditions for ultraviolet irradiation will be described later.
In the ultraviolet treatment, as shown in FIG. 3, the ultraviolet ray irradiation light source 202 is opposed to the surface (outer peripheral surface) of the conductive elastic roller 200, and the conductive elastic roller 200 is rotated in the direction of arrow A (arrow B). ). The length of the ultraviolet irradiation light source is set longer than the length of the conductive elastic roller so that the ultraviolet rays are efficiently irradiated. For this reason, the surface of the conductive elastic roller 200 is irradiated with ultraviolet rays with good uniformity.
Preferred conditions for the ultraviolet treatment will be described later.

The diameter of the charging roller in the present embodiment is preferably 8 mm or more and 15 mm or less, more preferably 9 mm or more and 14 mm or less. The wall thickness of the charging layer is preferably 1.5 mm to 4 mm. If the diameter is larger than 15 mm, the number of discharges per peripheral surface is reduced, which is excellent in long-term stability with respect to charging performance, but may be disadvantageous from the viewpoint of miniaturization. If the diameter is smaller than 8 mm, the image forming apparatus 50 is downsized, which is advantageous. However, the number of discharges per peripheral surface increases, which may be disadvantageous for long-term stability.
Hereinafter, although the charging roller in this embodiment is demonstrated in detail, it is not limited to the following structures.

As the material of the shaft, free-cutting steel, stainless steel, etc. are used, and the material and surface treatment method are selected as appropriate according to the application such as slidability. The conductive treatment may be performed by processing.
The conductive elastic layer constituting the charging layer of the charging roller 53 is formed using, for example, an elastic material such as rubber having elasticity, or a conductive material such as carbon black or ionic conductive material for adjusting the resistance of the conductive elastic layer. Is done. Furthermore, if necessary, materials that can be usually added to rubber, such as softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, anti-aging agents, and fillers such as silica and calcium carbonate, may be added. . The present embodiment is formed by coating the peripheral surface of a conductive shaft with a mixture obtained by adding the above-mentioned “material that can be added to normal rubber” to the elastic material and the conductive material. As a conductive agent for the purpose of adjusting the resistance value, a material in which a material that conducts electrons and / or ions as a charge carrier, such as carbon black or an ionic conductive agent blended in a matrix material, may be used.

  The elastic material constituting the conductive elastic layer is formed, for example, by dispersing a conductive agent in a rubber material. Rubber materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, urethane rubber, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide. -Allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber, natural rubber and the like, and blended rubbers thereof. Among these, silicone rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, acrylonitrile-butadiene copolymer rubber, and blended rubbers thereof are preferably used. These rubber materials may be foamed or non-foamed.

  As the conductive agent, an electronic conductive agent or an ionic conductive agent is used. Examples of electronic conductive agents include carbon blacks such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, and stainless steel; tin oxide, indium oxide, titanium oxide And fine powders such as various conductive metal oxides such as tin oxide-antimony oxide solid solution, tin oxide-indium oxide solid solution, and the like. Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium; perchlorates and chlorates of alkaline earth metals ;

  These conductive agents may be used alone or in combination of two or more. Further, the amount of addition is not particularly limited, but in the case of the electronic conductive agent, it is preferably in the range of 1 part by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber material. In the case of an agent, it is preferably in the range of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the rubber material.

  The surface layer that may be provided on the elastic layer is formed to prevent contamination by foreign matters such as toner, but is substituted by ultraviolet irradiation to the conductive elastic layer. Therefore, it may be excluded from the viewpoint of productivity and cost. The material for the surface layer may be any of resin, rubber and the like, and is not particularly limited. For example, polyester, polyimide, copolymer nylon, silicone resin, acrylic resin, polyvinyl butyral, ethylene tetrafluoroethylene copolymer Polymer materials such as coalescence, melamine resin, fluororubber, epoxy resin, polycarbonate, polyvinyl alcohol, cellulose, polyvinylidene chloride, polyvinyl chloride, polyethylene, and ethylene vinyl acetate copolymer are used.

  Of these, polyvinylidene fluoride, a tetrafluoroethylene copolymer, polyester, polyimide, and copolymer nylon are preferably used from the viewpoint of contamination of the external additive. The copolymer nylon includes one or more of 610 nylon, 11 nylon, and 12 nylon as polymerized units, and the other polymer units contained in the copolymer include 6 nylon. 66 nylon and the like. Here, it is preferable that the proportion of polymer units composed of 610 nylon, 11 nylon, and 12 nylon contained in the copolymer is 10% or more in total by mass ratio. When the above polymerized unit is 10% or more, it is excellent in liquid preparation and film-forming properties at the time of coating the surface layer, and in particular, there is little abrasion of the resin layer and adhesion of foreign matter to the resin layer during repeated use, and durability of the roll Is excellent, and changes in properties due to the environment are reduced.

  The above polymer materials may be used alone or in combination of two or more. Further, the number average molecular weight of the polymer material is preferably in the range of 1,000 or more and 100,000 or less, and more preferably in the range of 10,000 or more and 50,000 or less.

The surface layer may contain a conductive material to adjust the resistance value. The conductive material preferably has a particle size of 3 μm or less.
Further, as a conductive agent for the purpose of adjusting the resistance value, for example, carbon black and conductive metal oxide particles blended in a matrix material, or ions and / or ions such as an ionic conductive agent are used as charge carriers. A material in which a material that conducts electricity is dispersed is used.
Specifically, carbon black as a conductive agent includes “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, “Special Black 4” manufactured by Degussa, "Special Black 4A", "Special Black 550", "Special Black 6", "Color Black FW200", "Color Black FW2", "Color Black FW2V", "MONARCH1000" manufactured by Cabot, Cabot “MONARCH1300” manufactured by the company, “MONARCH1400” manufactured by Cabot, “MOGUL-L”, “REGAL400R”, and the like.

  The carbon black has a pH of 4.0 or less, and has better dispersibility in the resin composition due to the effect of the oxygen-containing functional group present on the surface compared to general carbon black. By blending, the charging uniformity is improved and the fluctuation of the resistance value is further reduced.

  The conductive metal oxide particles, which are conductive particles for adjusting the resistance value, are conductive particles such as tin oxide, tin oxide doped with antimony, zinc oxide, anatase titanium oxide, and ITO. Any conductive agent that uses electrons as charge carriers may be used without any particular limitation. These may be used alone or in combination of two or more. In addition, any particle size may be used as long as the present embodiment is not impaired, but from the viewpoint of resistance value adjustment and strength, tin oxide, antimony-doped tin oxide, anatase-type titanium oxide, Furthermore, tin oxide and tin oxide doped with antimony are preferred.

By performing resistance control with the conductive material, the resistance value of the surface layer does not change depending on environmental conditions, and stable characteristics can be obtained.
Further, a fluorine-based or silicone-based resin is used for the surface layer. In particular, it is preferably composed of a fluorine-modified acrylate polymer. Moreover, you may add particle | grains in a surface layer. As a result, the surface layer becomes hydrophobic and acts to prevent the adhesion of foreign matter to the charging roller. In addition, insulating particles such as alumina and silica are added to provide irregularities on the surface of the charging roller, reducing the burden during rubbing against the photosensitive drum, and providing resistance to abrasion between the charging roller and the photosensitive drum. Wearability may be improved.

Next, the details of the ultraviolet irradiation process to the charging roller will be described.
The ultraviolet wavelength in the ultraviolet treatment is preferably from 100 nm to 400 nm, more preferably from 150 nm to 300 nm. When the ultraviolet wavelength is less than 100 nm, the polar group present on the roller surface is hardly activated, and the roller surface may not be sufficiently modified. On the other hand, when the ultraviolet wavelength exceeds 400 nm, the activation of polar groups on the roller surface may proceed excessively, which may lead to decomposition or deterioration.
The ultraviolet irradiation intensity in the ultraviolet treatment is preferably 100 J (joule) or more and 5000 J (joule) or less, more preferably 600 J (joule) or more and 2000 J (joule) or less. If the ultraviolet illuminance intensity is less than 100 J (joules), the polar groups present on the roller surface are hardly activated, and the roller surface may not be sufficiently modified. On the other hand, when the ultraviolet illuminance intensity exceeds 5000 J (joules), the activation of the polar group on the roller surface may proceed excessively, which may lead to decomposition or deterioration.
Here, the ultraviolet irradiation intensity is a value obtained by the formula: illuminometer measurement value (mW) × irradiation time (sec) = J (joule) at a distance from the ultraviolet light source to the object to be processed (conductive elastic roller). It is.
The charging roller in the present embodiment is manufactured by performing the above-described ultraviolet irradiation treatment on the surface.

Further, the charging roller in the present embodiment rotates by contacting the surface of the charging roller with the surface of an image holding member (for example, a photosensitive drum (electrophotographic photosensitive member)), and charges the image holding member only with a DC voltage. Hereinafter, the potential of the image carrier charged by the charging roller may be referred to as “charging potential”.
The charging potential in the DC charging method is generally controlled to be about −300 V to −500 V from the viewpoints of uneven charging density, power supply capacity, and the like, but the charging roller of this embodiment considers the service life. Even when the charging potential is low, color streaks in the formed image are suppressed.
On the other hand, when the charging potential is closer to 0V than -100V, the difference between the development potential and the exposure potential described below cannot be sufficiently secured, and the color streak may deteriorate. For this reason, the charging potential is preferably −100 V or less.
From the viewpoint of coexistence of the service life and color stripe suppression, the charging potential is more preferably −100 V or less and −400 V or more, and particularly preferably −100 V or less and −300 V or more.

Next, details of the developing device (for example, the developing device 34 in FIG. 1 and the developing devices (55Y, 55M, 55C, and 55K) in FIG. 2) in the present embodiment will be described.
The developing device in this embodiment is a device that obtains a toner image by developing an electrostatic latent image formed on the surface of an image carrier (photosensitive drum) by exposure or the like with toner.
The developing device in the present embodiment includes, for example, a developer containing toner, and a developing roll (for example, a circular member in the developing device 34 in FIG. 1) for attaching the toner to the image holding member. This is a known configuration. If necessary, a blade for removing the toner excessively attached to the developing roll may be provided.

  In addition, a predetermined potential (for example, a potential having the same polarity as the charging potential; hereinafter, also referred to as “developing potential”) is applied to the developing device (for example, the surface of the developing roll) in the present embodiment. Is preferred. The development potential is a potential (charging potential or charging potential) between a charging potential that is the potential of the image carrier charged by the charging roller and the potential of the image carrier after exposure (hereinafter also referred to as “exposure potential”). (Including the case where the potential is the same as the exposure potential).

In general, the larger the absolute value of the difference between the charging potential and the developing potential is, the more advantageous for suppressing color streaks, and the absolute value of the difference between the normal charging potential and the developing potential is set to be 50 V or more and 150 V or less. ing.
On the other hand, in the charging roller of the present embodiment, the absolute value of the difference between the charging potential and the developing potential can be set smaller, and even if the charging potential is low, sufficient development potential and exposure potential can be maintained while suppressing color streaks. A difference can be secured.
Specifically, the absolute value of the difference between the charging potential and the developing potential is preferably 30 V or less.

  The charging potential, the exposure potential, the developing potential, and the absolute value of the difference between the charging potential and the developing potential are described in detail in, for example, Japanese Patent Laid-Open Nos. 2005-265970 and 2005-266305. Yes.

Next, the details of the developer in this embodiment will be described.
The developer in this embodiment contains at least a toner. If necessary, an external additive may be further contained.
As the toner in the developer, a polymerized toner prepared by a polymerization method is preferably used. Due to the irregular shape of the toner, the fluidity may not be sufficient even with the addition of a fluidity aid, and due to the mechanical shearing force during use, the particles on the toner surface move to the toner recesses over time. The developability / transferability / cleanability may deteriorate due to the decrease in fluidity or the embedding of the fluidity aid in the toner. Further, when the toner collected by cleaning is returned to the developing machine and used again, the image quality is likely to further deteriorate. Increasing the flow aid to prevent these may cause contamination, filming, scratches, etc. on the photoreceptor.

  Therefore, as a means for intentionally controlling the toner shape and the surface structure, a method for producing a toner by an emulsion polymerization aggregation method has been proposed. These are generally prepared by dispersion of resin particles by a polymerization method such as emulsion polymerization, and on the other hand, by preparing a colorant particle dispersion in which a colorant is dispersed in a solvent, mixing them, and then heating and / or pH. The above-mentioned resin particles and colorant are aggregated to a desired particle size by control, addition of a flocculant, etc., and then the aggregated particles are stabilized at a desired particle size, and then the temperature is equal to or higher than the glass transition point of the resin particles. The toner is produced by overheating and fusing.

  The toner particles obtained by the emulsion polymerization aggregation method have extremely superior characteristics (particularly sharp particle size distribution) compared to the toner particles obtained by other polymerization methods represented by the conventional suspension polymerization method. And does not require a classification operation), and if this is used as a toner, high quality image quality can be obtained over a long period of time. In addition, the toner production method by the emulsion polymerization aggregation method is such that the aggregated particles are heated and fused to the glass transition point (Tg) or higher of the resin particles, so that the shape of the irregular shape can be controlled by controlling the heating method and pH. Since toners of various shapes up to a spherical particle state are produced, the shape is selected in a range from a so-called potato shape to a spherical shape in the electrophotographic system to be used.

  The external additive in the developer is not particularly limited, but desired materials such as spherical silica, titanium oxide, cerium oxide, zinc stearate, polytetrafluoroethylene (PTFE), methyl methacrylate resin (PMMA), Used for each purpose. These external additives are used for improving the fluidity of the developer, improving transfer properties, improving charging properties, and the like. Among these, spherical silica is preferably included for improving the cleaning property of the photoreceptor. The reason for this is that silica has a refractive index of around 1.5, and even if the particle size is increased, the decrease in transparency due to light scattering is not affected.

On the other hand, general fumed silica has a specific gravity of 2.2, and the maximum particle size of 50 nm may be a limit in production. Further, although the particle size increases as an aggregate, the dispersion uniformity may be inferior, and the sealing effect may not be exhibited stably.
Silica suitable as a material for the external additive contained for improving the cleaning property, particularly spherical monodispersed silica having a specific gravity of 1.3 or more and 1.9 or less can be obtained, for example, by a sol-gel method which is a wet method. Since the sol-gel method is a wet method and is a method of producing without firing, the specific gravity is controlled to be lower than other methods such as a vapor phase oxidation method. Further, the specific gravity may be further adjusted by controlling the type of hydrophobic treatment agent or the amount of treatment in the hydrophobization treatment step. The particle size of silica is freely controlled by the hydrolysis of the sol-gel method, the mass ratio of alkoxysilane, ammonia, alcohol, water in the condensation polymerization step, the reaction temperature, the stirring rate, and the supply rate. A monodispersed spherical silica is also formed by the sol-gel method.

A specific method for producing silica is as follows.
First, a silane compound such as tetramethoxysilane is dropped into a mixed solution of water and alcohol using an aqueous ammonia as a catalyst while applying temperature, and the mixture is stirred. Next, the produced silica sol suspension is centrifuged to separate it into wet silica gel, alcohol and aqueous ammonia. Add solvent to wet silica gel again to form silica sol, add hydrophobizing agent, know or make surface hydrophobic. As the hydrophobic treatment, for example, a general silane compound is used. Next, the target silica is obtained by removing the solvent from the hydrophobized silica sol, drying, and sieve. Moreover, you may perform the process by the above-mentioned sol-gel method again obtained in this way.

Next, details of the image carrier (for example, the photosensitive drum 30 in FIG. 1 and the photosensitive drum 52 in FIG. 2) in the present embodiment will be described with reference to FIG.
As shown in FIG. 4, the image carrier (for example, a photosensitive drum (electrophotographic photosensitive member)) includes a conductive support 1, an undercoat layer 2 formed on the substrate, and an undercoat layer. 2 and a photosensitive layer 3 formed on the substrate 2. Further, the photosensitive layer 3 may have a two-layer structure of a charge generation layer 5 and a charge transport layer 6 as shown in FIGS. Further, as shown in FIGS. 6 and 7, a protective layer 4 may be provided on the photosensitive layer 3.

Examples of the conductive support 1 include a metal drum made of aluminum, copper, iron, nickel, etc .; aluminum, copper, gold, silver, platinum, palladium, titanium, nickel-chromium, stainless steel on a cylindrical substrate such as glass or plastic. Steel, body-deposited metal such as indium, or deposited conductive metal compound such as indium oxide or tin oxide; laminated metal foil on the substrate, carbon black, indium oxide, tin oxide, Antimony oxide powder, metal powder, copper iodide and the like are dispersed in a binder resin, and a conductive treatment is applied by applying it.
It is particularly preferable that the undercoat layer 2 contains silane-coupled metal oxide particles. As the metal oxide particles used, zinc oxide, titanium oxide, tin oxide alone, or a combination thereof is used. In particular, zinc oxide and titanium oxide are preferably used because of their high electron mobility and good electrophotographic characteristics.

When the silane-coupled metal oxide particles are used, the undercoat layer 2 preferably has a powder resistance of about 10 ² Ω · cm to 10 ¹¹ Ω · cm in order to obtain the volume resistance. . Among these, it is preferable to use metal oxide particles such as tin oxide, titanium oxide, and zinc oxide having the resistance value.

If the powder resistance value of the metal oxide particles contained in the undercoat layer 2 is less than 10 ² Ωcm, the volume resistance range may not be obtained for the undercoat layer 2. If the powder resistance value is greater than 10 ¹¹ Ωcm, the residual potential on the photosensitive drum may easily increase when the photosensitive drum is mounted on the image forming apparatus.

Further, two or more kinds of metal oxide particles having different surface treatments or particles having different particle diameters may be mixed and used. As the metal oxide particles, those having a specific surface area of 10 m ² / g or more are preferably used. Those having a specific surface area value of 10 m ² / g or less tend to cause a decrease in chargeability, and it may be difficult to obtain good electrophotographic characteristics.

  The metal oxide particles are particularly preferably subjected to a surface treatment with a silane coupling agent. By applying a surface treatment with a silane coupling agent, the desired volume resistance is adjusted. Furthermore, a silane coupling agent having an amino group is preferably used in order to give a good blocking property to the undercoat layer 2.

  Any silane coupling agent having an amino group may be used as long as the desired photoreceptor characteristics can be obtained. Specific examples include γ-aminopropyltriethoxysilane, N-β- (amino Ethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and the like. However, it is not limited to these. Two or more silane coupling agents may be mixed and used. Examples of the silane coupling agent used in combination with the silane coupling agent having an amino group include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4- Epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ- Aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane Etc., but these Not intended to be constant.

  Any surface treatment method may be used as long as it is a known method, but a dry method or a wet method is preferable.

  When surface treatment is performed by a dry method, a silane coupling agent dissolved directly or in an organic solvent is added dropwise and sprayed with dry air or nitrogen gas while stirring the metal oxide particles with a mixer having a large shearing force. Can be processed with good uniformity. The addition or spraying is preferably performed at a temperature below the boiling point of the solvent. Spraying at a temperature equal to or higher than the boiling point of the solvent is not preferred because it causes the solvent to evaporate before being stirred with good uniformity, causing the silane coupling agent to locally accumulate, making it difficult to perform processing with good uniformity. After addition or spraying, for example, baking is performed at 100 ° C. or higher.

  As a wet method, the metal oxide particles are stirred in a solvent, dispersed using an ultrasonic wave, a sand mill, an attritor, a ball mill, etc., added with a silane coupling agent solution and stirred or dispersed, and then the solvent is removed. Processed with good uniformity. The solvent removal method is distilled off by filtration or distillation. After the solvent is removed, baking is further performed at, for example, 100 ° C. In the wet method, the water containing metal oxide particles can be removed before adding the surface treatment agent. For example, a method of removing with stirring and heating in the solvent used for the surface treatment, removing by azeotroping with the solvent. You may use the method to do.

The amount of the silane coupling agent with respect to the metal oxide particles in the undercoat layer 2 is not particularly limited.
In addition, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-2-methoxyethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyl Triethoxysilane, γ-chloropropyltrimethoxysilane, γ-2-aminoethylaminopropyltrimethoxysilane, γ-mercapropropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, β-3,4-epoxycyclohexyltri A silane coupling agent such as methoxysilane may be contained and used. Furthermore, polyvinyl alcohol, polyvinyl methyl ether, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, polyamide, polyimide, casein, gelatin, polyethylene, conventionally used for the undercoat layer Known binder resins such as polyester, phenol resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, polyvinyl pyrrolidone, polyvinyl pyridine, polyurethane, polyglutamic acid, and polyacrylic acid may be used. These mixing ratios are set as necessary.

  In order to control the volume resistance in the undercoat layer 2, organic pigments such as perylene pigments, bisbenzimidazole perylene pigments, polycyclic quinone pigments, indigo pigments, quinacridone pigments described in JP-A-47-30330, Also, an electron-accepting substance such as a bisazo pigment having an electron-withdrawing substituent such as a cyano group, a nitro group, a nitroso group, or a halogen atom, or an organic pigment such as a phthalocyanine pigment is mixed / dispersed together with the metal oxide particles. Are preferably used. Among these pigments, perylene pigments, bisbenzimidazole perylene pigments and polycyclic quinone pigments are preferably used. In addition, the surface of these pigments may be surface-treated with the above coupling agent or binder for the purpose of controlling dispersibility and charge acceptability.

  As the mixing / dispersing method, a conventional method using a ball mill, a roll mill, a sand mill, an attritor, an ultrasonic wave, or the like is applied. Mixing / dispersing is carried out in an organic solvent, as long as the organic solvent dissolves the resin and does not cause gelation or aggregation when the inorganic metal compound and the electron-accepting pigment are mixed / dispersed. Any one may be used. For example, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene Ordinary organic solvents such as toluene are used alone or in admixture of two or more.

  Furthermore, in order to prevent light reflection of the conductive support 1, resin particles having a particle size of 1.0 μm or more may be dispersed and used. In this case, the resin particles are mixed / dispersed after the light transmittance of the undercoat layer 2 is determined, for example.

The film thickness of the undercoat layer 2 of the photosensitive drum is preferably from 0.1 μm to 40 μm, and more preferably from 10 μm to 40 μm. As the coating method used when the undercoat layer 2 is provided, the usual methods such as blade coating method, Mayer bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method, etc. May be used. The coated layer is dried to obtain an undercoat layer. Usually, drying is performed at a temperature suitable for film formation by evaporating the solvent.
If the volume resistance of the photosensitive drum cannot be maintained, it is difficult to determine the optimum transfer voltage, and it may not be possible to prevent a decrease in image density, roughness, or the like. Therefore, it is important to control the volume resistance of the undercoat layer that is not affected by wear or scratches as described above.

The charge generation layer 5 is made of, for example, a known charge generation material and a binder resin.
The charge generation material is preferably a metal phthalocyanine pigment. The hydroxygallium phthalocyanine used in the present embodiment is produced by a known method disclosed in, for example, Japanese Patent Laid-Open Nos. 5-263007 and 5-279591.
The binder resin is selected from a wide range of insulating resins. Moreover, it selects from organic photoconductive polymers, such as poly-N-vinyl carbazole, polyvinyl anthracene, polyvinyl pyrene, polysilane. Preferred binder resins include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin. Insulating resins such as polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin are not limited thereto. These binder resins are used alone or in combination of two or more.

  The mixing ratio of the charge generation material and the binder resin (mass ratio) is preferably in the range of 10: 1 to 1:10. Further, as a method for dispersing them, for example, a normal method such as a ball mill dispersion method, an attritor dispersion method, a sand mill dispersion method, or the like is used. At this time, a condition that the crystal form of the pigment is not changed by the dispersion is required. . Incidentally, it has been confirmed that the crystal form is not changed before dispersion in any of the dispersion methods implemented in this embodiment. Further, at the time of this dispersion, it is effective to make the particles have a particle size of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less. Moreover, as a solvent used for these dispersions, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran Ordinary organic solvents such as methylene chloride, chloroform, chlorobenzene and toluene are used alone or in admixture of two or more.

  The thickness of the charge generation layer 5 used in this embodiment is generally 0.1 μm or more and 5 μm or less, preferably 0.2 μm or more and 2.0 μm or less. Further, as a coating method used when the charge generation layer 5 is provided, usual methods such as a blade coating method, a Mayer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method are used. Is used. Further, a pigment treated for the purpose of increasing the dispersion stability of the pigment, photosensitivity, or stabilizing electrical characteristics may be used.

As the charge transport layer 6, a layer formed by a known technique is used. These charge transport layers 6 are formed containing a desired charge transport material and a binder resin, or are formed containing a polymer charge transport material.
Examples of charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, xanthone compounds, benzophenone compounds , Electron transport compounds such as cyanovinyl compounds and ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. Examples thereof include pore-transporting compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto. These charge transport materials are used alone or in combination of two or more. From the viewpoint of mobility, compounds represented by the following formula (A), formula (B) or formula (C) are preferred.

In formula (A), R ¹ represents a hydrogen atom or a methyl group. N means an integer of 1 or 2. Ar ¹ and Ar ² represent a substituted or unsubstituted aryl group, and the substituent includes a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or A substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

In formula (B), R ² and R ^{2 ′} may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ³ , R ^{3 ′} , R ⁴ and R ^{4 ′} may be the same or different, and are a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a carbon number. An amino group substituted with 1 or more and 2 or less alkyl groups, a substituted or unsubstituted aryl group, or —C (R ⁵ ) ═C (R ⁶ ) (R ⁷ ), —CH═CH—CH═C ( Ar ′) ₂ R ⁵ , R ⁶ and R ⁷ represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Ar ′ represents a substituted or unsubstituted aryl group. m and n are integers of 0 or more and 2 or less.

In the formula (C), R ⁸ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, or —CH═CH—CH═C. (Ar ″) ₂ is represented. Ar ″ represents a substituted or unsubstituted aryl group. R ⁹ and R ¹⁰ may be the same or different and substituted with a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 2 carbon atoms Represents a substituted amino group or a substituted or unsubstituted aryl group.

  Further, examples of the binder resin used for the charge transport layer 6 include polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, and styrene-butadiene copolymer. , Vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, Poly-N-vinylcarbazole, polysilane, and a polymer charge transport material such as a polyester-based polymer charge transport material disclosed in JP-A-8-176293 and JP-A-8-208820 are used. These binder resins are used alone or in combination of two or more.

  Moreover, you may use a polymeric charge transport material independently. As the polymer charge transport material, for example, known materials having charge transport properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 have a high charge transporting property and are particularly preferable. The polymer charge transporting material alone is used as a charge transporting layer, but may be mixed with the binder resin to form a film.

  The charge transport layer 6 may further contain a fluororesin. The content of the fluorine-based resin in the charge-transporting layer 6 in the charge-transporting layer 6 containing the fluorine-based resin is suitably from 0.1% by mass to 40% by mass with respect to the total amount of the material constituting the charge-transporting layer 6, Particularly, it is preferably 1% by mass or more and 30% by mass or less. If the content of the fluororesin in the charge transport layer 6 is less than 1% by mass, the modification effect due to the dispersion of the fluororesin particles may not be sufficient. On the other hand, if it exceeds 40% by mass, the light transmission property decreases. In addition, when the photosensitive drum is mounted on the image forming apparatus, the residual potential may increase due to repeated use.

  Examples of the fluorine resin particles used in the present embodiment include a tetrafluoroethylene resin, a trifluorinated ethylene resin, a hexafluoropropylene resin, a vinyl fluoride resin, a vinylidene fluoride resin, a difluorodiethylene chloride resin, and the like. It is desirable to select one or more of these copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

  The primary particle size of the fluororesin is preferably 0.05 μm or more and 1 μm or less, more preferably 0.1 μm or more and 0.5 μm or less. When the primary particle size is less than 0.05 μm, aggregation at the time of dispersion may easily proceed. On the other hand, if it exceeds 1 μm, an image quality defect may easily occur.

  Examples of the charge transport material used in this embodiment include oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, and 1,3,5-triphenyl. -Pyrazoline, pyrazoline derivatives such as 1- [pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, tri (p-methylphenyl) aminyl-4 Aromatic tertiary amino compounds such as amine and dibenzylaniline, aromatic tertiary diamino compounds such as N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine, 3- (4 1,2,4-triazine derivatives such as' -dimethylaminophenyl) -5,6-di- (4'-methoxyphenyl) -1,2,4-triazine, A hydrazone derivative such as diethylaminobenzaldehyde-1,1-diphenylhydrazone, a quinazoline derivative such as 2-phenyl-4-styryl-quinazoline, a benzofuran derivative such as 6-hydroxy-2,3-di (p-methoxyphenyl) benzofuran, Hole transport such as α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N-diphenylaniline, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, poly-N-vinylcarbazole and derivatives thereof Substances, quinone compounds such as chloranil and broanthraquinone, tetraanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, xanthone Compounds, thiophene compounds And a polymer having a group consisting of the above-described compounds in the main chain or side chain. These charge transport materials are used alone or in combination of two or more.

  As the binder resin used in the present embodiment, for example, acrylic resin, polyarylate, polyester resin, polycarbonate resin such as bisphenol A type or bisphenol Z type, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer Insulating resins such as polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, and chlorine rubber, and organic photoconductive polymers such as polyvinyl carbazole, polyvinyl anthracene, and polyvinyl pyrene.

  The charge transport layer 6 may be formed by applying and drying a solution in which the charge transport material and the binder resin shown above are dissolved in a suitable solvent. Examples of the solvent used for forming the charge transport layer 6 include aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, and n-butanol, acetone, cyclohexanone, and 2-butanone. Such as ketone solvents, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether, or mixed solvents thereof. Use.

  As a method for dispersing the fluorine-based resin in the charge transport layer 6, a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a high-pressure homogenizer, an ultrasonic disperser, a colloid mill, a collision-type medialess disperser, a through-type medialess A method such as a disperser is used.

  Examples of the dispersion of the coating liquid for forming the charge transport layer 6 include a method of dispersing the fluororesin particles in a solution such as a binder resin or a charge transport material dissolved in a solvent.

In the step of producing the coating liquid for forming the charge transport layer 6, it is preferable to control the temperature of the coating liquid in the range of 0 ° C. or higher and 50 ° C. or lower.
As a method of adjusting the temperature of the coating liquid in the coating liquid manufacturing process to 0 ° C. or higher and 50 ° C. or lower, cool with water, cool with wind, cool with refrigerant, adjust the room temperature of the manufacturing process, warm with hot water, hot air Use heating, heating with a heater, making a coating liquid manufacturing facility with a material that does not easily generate heat, creating a coating liquid manufacturing facility with a material that easily dissipates heat, or creating a coating liquid manufacturing facility with a material that easily stores heat Is done.

  As a premixing method for the coating liquid, methods such as a stirrer, stirring with a stirring blade, a roll mill, a sand mill, an attritor, a ball mill, a high-pressure homogenizer, and an ultrasonic disperser are used. As a dispersion method, a sand mill, an attritor, a ball mill, a high-pressure homogenizer, an ultrasonic disperser, a roll mill, or the like is used.

  In the present embodiment, it is also effective to add a small amount of a dispersion aid in order to improve the dispersion stability of the dispersion and to prevent aggregation at the time of coating film formation. Examples of the dispersion aid include fluorine-based surfactants, fluorine-based polymers, silicone-based polymers, and silicone oils.

  As a coating method, a usual method such as a blade coating method, a Mayer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. Furthermore, as a solvent used when the charge transport layer 6 is provided, aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halongen such as methylene chloride, chloroform and ethylene chloride Ordinary organic solvents such as cyclic aliphatic hydrocarbons, cyclic ethers such as tetrahydrofuran and ethyl ether, etc., or a mixture of two or more thereof are used. Additives such as antioxidants, light stabilizers, and heat stabilizers are added to the photosensitive layer to prevent photoconductor deterioration caused by ozone, oxidizing gas, or light or heat generated in the copying machine. To do.

  For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. Examples of the light stabilizer include derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine. Further, for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, etc., at least one electron accepting substance is contained.

Examples of the electron acceptor used in the photosensitive drum include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, and o-dioxide. Examples thereof include nitrobenzene, m-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, phthalic acid and the like, and compounds represented by the general formula (I). Of these, benzene derivatives having electron-withdrawing substituents such as fluorenone-based, quinone-based, Cl, CN, and NO ₂ are particularly preferable.

  The film thickness of the photosensitive layer (or charge transport layer) is preferably 20 μm or more and 40 μm or less, and more preferably 25 μm or more and 30 μm or less. If the thickness is less than 20 μm, it may be impossible to achieve a sufficiently long life, and if it exceeds 40 μm, the photosensitive drum may not be sufficiently charged and may not be used as an image forming apparatus.

  EXAMPLES Hereinafter, although this invention is demonstrated using an Example, this invention is not limited at all by these Examples. In the following examples, “part” means part by mass.

[Example 1]
<Charging roller>
3 parts by mass of ionic conductive agent PEL-100 (manufactured by Nippon Carlit Co., Ltd.) was added to 100 parts by mass of epichlorohydrin rubber and sufficiently kneaded, and the resulting kneaded product (conductive elastic material) was extruded.
Next, a SUM-Ni shaft having a diameter of 6.00 mm (a nickel-plated sulfur free-cutting steel; core) was inserted into the obtained molded product, and molded and vulcanized with a press molding machine. Further, the outer diameter (diameter) was processed to be 9.00 mm by polishing.
Thus, a conductive elastic roller having a conductive elastic layer on the SUM-Ni shaft was obtained.

Next, the conductive elastic roller obtained above was subjected to surface treatment with ultraviolet rays.
As shown in FIG. 3, the surface treatment with ultraviolet rays was performed using a low-pressure mercury lamp as the ultraviolet irradiation light source 202. The wavelength of the low-pressure mercury lamp is 185 nm. The distance between the low-pressure mercury lamp and the surface of the conductive elastic roller 200 was 10 mm. The illuminance measured at a position 10 mm away from the low-pressure mercury lamp 202 was 10 mW. The irradiation time was 180 sec. In this case, the ultraviolet irradiation intensity is 10 mW × 180 sec = 1800 [J].
As described above, the charging roller 1 in which the surface of the conductive elastic roller was irradiated with ultraviolet rays was obtained.

<Photosensitive drum>
100 parts by mass of zinc oxide (average particle size 70 nm: prototype manufactured by Teika: specific surface area value 15 m ² / g) is stirred and mixed with 500 parts by mass of toluene, and a silane coupling agent (KBM603: manufactured by Shin-Etsu Chemical Co., Ltd.) 1.25 Part by mass was added and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain zinc oxide surface-treated with a silane coupling agent.

  60 parts by mass of the surface-treated zinc oxide, 0.3 parts by mass of alizarin (manufactured by Sigma Aldrich Japan), 13.5 parts by mass of blocked isocyanate (Sumidule 3175, a curing agent manufactured by Sumitomo Bayern Urethane Co., Ltd.), and butyral 38 parts by mass of a solution (resc BM-1, manufactured by Sekisui Chemical Co., Ltd.) of 15 parts by mass in 85 parts by mass of methyl ethyl ketone and 25 parts by mass of methyl ethyl ketone were mixed, and the mixture was put into a sand mill using glass beads having a diameter of 1 mm. And dispersed. Dioctyltin dilaurate: 0.005 parts by mass and silicone resin particle Tospearl 145 (manufactured by GE Toshiba Silicone): 4.0 parts by mass were added as catalysts to the resulting dispersion to obtain an undercoat layer coating solution. This coating solution was applied onto an aluminum substrate having a diameter of 24 mm and a wall thickness of 1 mm by a dip coating method, followed by drying and curing at 180 ° C. for 24 minutes to obtain an undercoat layer having a thickness of 25 μm.

Next, a photosensitive layer composed of a charge generation layer and a charge transport layer was formed on the obtained undercoat layer as follows.
First, a mixture comprising 15 parts of hydroxygallium phthalocyanine as a charge generating substance, 10 parts of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Union Carbide) as a binder resin, and 200 parts of n-butyl acetate was prepared. 1 mmφ glass beads were used for dispersion for 4 hours in a sand mill. To the obtained dispersion, 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added and stirred to obtain a coating solution for a charge generation layer. This charge generation layer coating solution was dip coated on the undercoat layer and dried at room temperature (25 ° C.) to form a charge generation layer having a thickness of 0.2 μm.

Next, 4 parts of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine and bisphenol are formed on the formed charge generation layer. A coating solution prepared by adding 6 parts by mass of Z polycarbonate resin (viscosity average molecular weight 40,000) to 80 parts by mass of tetrahydrofuran was applied and dried at 135 ° C. for 25 minutes. As a result, a charge transport layer having a thickness of 30 μm was formed on the charge generation layer.
As described above, a photosensitive layer composed of a charge generation layer and a charge transport layer was formed on the undercoat layer, and a photosensitive drum 1 for electrophotography was obtained.

<Process cartridge and image forming apparatus>
The charging roller 1 and the photosensitive drum 1 manufactured as described above were modified into a process cartridge of CELL 3110cn manufactured by DELL and incorporated into the apparatus, whereby the image forming apparatus 1 was obtained.
The charging roller 1 and the photosensitive drum 1 were previously adjusted to a length suitable for the CELL C3110cn.

<Evaluation>
Using the image forming apparatus 1 obtained as described above, a continuous print test was performed with a test pattern in which the entire surface of the A4 size paper was halftone in an environment of 28 ° C. and 85%.
At this time, the photosensitive drum 1 was charged by a DC charging method in which only a DC voltage was applied to the charging roller. The voltage applied to the charging roller was adjusted so that the photoreceptor surface potential (charging potential) was −300V. Further, the surface potential (developing potential) of the developing roll of the developing device was adjusted to be −210V. That is, the absolute value of the difference between the charging potential and the developing potential was 90V.
The surface potential of the photoreceptor and the surface potential of the developing roll were measured with a surface potential meter Trek model 344 (manufactured by Trek Japan).
For the test pattern, the color streak was evaluated as follows.

-Evaluation of color stripes-
Print images were extracted when the first, tenth, 100th, 1000th, 10000th, and 100000th sheets were traveled, and minute color streaks in the image were counted to determine pass / fail. In the A4 image, the pass / fail judgment was ○ when the color streak was 6 or less (1 per 100 cm ² ) in the A4 image, and x when 7 or more. The obtained results are shown in Table 1.

[Example 2]
In the charging roller 1 produced in Example 1, a conductive elastic roller was produced as the charging roller 2 in the same manner as in Example 1 except that the ultraviolet irradiation intensity was 10 mW × 500 sec = 5000 [J]. A continuous printing test and color streak evaluation were performed in the same manner as in Example 1 except for the charging roller. The obtained results are shown in Table 1.

Example 3
In the charging roller 1 produced in Example 1, a conductive elastic roller was produced as the charging roller 3 in the same manner as in Example 1 except that the ultraviolet irradiation intensity was set to 10 mW × 10 sec = 100 [J]. A continuous printing test and image quality evaluation (evaluation of color stripes) were carried out in the same manner as in Example 1 except for the charging roller. The obtained results are shown in Table 1.

Example 4
In the electrophotographic photosensitive drum 1 produced in Example 1, an electrophotographic photosensitive drum was produced in the same manner as in Example 1 except that the film thickness of the charge transport layer was 20 μm. A continuous printing test and image quality evaluation (evaluation of color stripes) were performed in the same manner as in Example 1 except for the photosensitive drum. The obtained results are shown in Table 1.

Example 5
Continuous printing test and image quality evaluation (evaluation of color streak) in the same manner as in Example 1 using the same charging roller and photosensitive drum as the charging roller 2 manufactured in Example 2 and the photosensitive drum 2 manufactured in Example 4. ). The obtained results are shown in Table 1.

Example 6
Continuous printing test and image quality evaluation (evaluation of color streak) in the same manner as in Example 1 using the same charging roller and photosensitive drum as the charging roller 3 manufactured in Example 3 and the photosensitive drum 2 manufactured in Example 4. ). The obtained results are shown in Table 1.

Example 7
In the electrophotographic photosensitive drum 1 produced in Example 1, an electrophotographic photosensitive drum was produced as in Photosensitive drum 3 in the same manner as in Example 1 except that the film thickness of the charge transport layer was 40 μm. A continuous printing test and image quality evaluation (evaluation of color stripes) were performed in the same manner as in Example 1 except for the photosensitive drum. The obtained results are shown in Table 1.

Example 8
Continuous printing test and image quality evaluation (evaluation of color streak) in the same manner as in Example 1 using the same charging roller and photosensitive drum as the charging roller 2 manufactured in Example 2 and the photosensitive drum 3 manufactured in Example 7. ). The obtained results are shown in Table 1.

Example 9
Continuous printing test and image quality evaluation (evaluation of color streak) in the same manner as in Example 1 using the charging roller 3 and the photosensitive drum 3 manufactured in Example 7 and the same charging roller and photosensitive drum as in Example 7. ). The obtained results are shown in Table 1.

Example 10
The surface layer was formed by treating the conductive elastic roller before irradiation with ultraviolet light produced in Example 1 as follows.
That is, 100 parts by mass of a saturated copolymerized polyester resin solution (Byron 30SS: manufactured by Toyobo Co., Ltd.), 26.3 parts by mass of a curing agent (amino resin solution Super Becamine G-821-60: manufactured by Dainippon Ink & Chemicals, Inc.) and A mixture of 10 parts by mass of a conductive agent (carbon black MONARCH1000: manufactured by Cabot Corporation) was dispersed with a bead mill, and the resulting dispersion was diluted with MEK to form the surface of the conductive elastic roller (the surface of the conductive elastic layer). After dip coating, it was dried by heating at 180 ° C. for 30 minutes to form a surface layer having a thickness of 7 μm.
Thus, a conductive elastic roller having a surface layer on the conductive elastic layer was obtained.

  Next, the obtained conductive elastic roller (conductive elastic roller having a surface layer on the conductive elastic layer) was subjected to ultraviolet irradiation treatment to obtain a charging roller 4. Here, the ultraviolet irradiation conditions were the same as in Example 1. Using the obtained charging roller 4 and the photosensitive drum 1 similar to that in Example 1, the same continuous printing test and image quality evaluation (evaluation of color stripes) as in Example 1 were performed. The obtained results are shown in Table 1.

Example 11
In the production of the charging roller 4 of Example 10, a conductive elastic roller was produced and used as the charging roller 5 in the same manner as in Example 10 except that the ultraviolet irradiation intensity was 10 mW × 500 sec = 5000 [J]. A continuous printing test and image quality evaluation (evaluation of color stripes) were carried out in the same manner as in Example 1 except for the charging roller. The obtained results are shown in Table 1.

Example 12
In the charging roller 4 manufactured in Example 10, a conductive elastic roller was manufactured and used as the charging roller 6 in the same manner as in Example 10 except that the ultraviolet irradiation intensity was set to 10 mW × 10 sec = 100 [J]. A continuous printing test and image quality evaluation (evaluation of color stripes) were carried out in the same manner as in Example 1 except for the charging roller. The obtained results are shown in Table 1.

Example 13
Continuous printing test and image quality evaluation (evaluation of color streak) in the same manner as in Example 1 using the charging roller 4 manufactured in Example 10 and the same charging roller and photosensitive drum as the photosensitive drum 2 manufactured in Example 4. ). The obtained results are shown in Table 1.

Example 14
A continuous printing test and image quality evaluation (evaluation of color streak) were carried out in the same manner as in Example 1 using the charging roller 5 prepared in Example 11 and the same charging roller and photosensitive drum as the photosensitive drum 2 manufactured in Example 4. ). The obtained results are shown in Table 1.

Example 15
A continuous printing test and image quality evaluation (evaluation of color streak) were carried out in the same manner as in Example 1 using the charging roller 6 prepared in Example 12 and the same charging roller and photosensitive drum as the photosensitive drum 2 manufactured in Example 4. ). The obtained results are shown in Table 1.

Example 16
A continuous printing test and image quality evaluation (evaluation of color stripes) were performed in the same manner as in Example 1 using the charging roller 4 and the photosensitive drum 3 manufactured in Example 7 and the same charging roller and photosensitive drum as those in Example 7. ). The obtained results are shown in Table 1.

Example 17
A continuous printing test and image quality evaluation (evaluation of color streak) were performed in the same manner as in Example 1 using the same charging roller and photosensitive drum as the charging roller 5 manufactured in Example 11 and the photosensitive drum 3 manufactured in Example 7. ). The obtained results are shown in Table 1.

Example 18
A continuous printing test and image quality evaluation (evaluation of color streaks) were performed in the same manner as in Example 1 using the same charging roller and photosensitive drum as the charging roller 6 manufactured in Example 12 and the photosensitive drum 3 manufactured in Example 7. ). The obtained results are shown in Table 1.

Example 19
After blending 5 parts by mass of carbon black and 2 parts by mass of a lithium perchlorate ionic conductive agent, using a homopolymer of epichlorohydrin sufficiently mixed with peroxide and further foaming agent, A foamed rubber elastic layer was formed. At this time, the core and the outer diameter of the roller were the same as those in Example 1. Thereafter, ultraviolet irradiation treatment was performed under the same conditions as in Example 1, and this was designated as the charging roller 7. Using the same photosensitive drum as in Example 1, the same continuous printing test and image quality evaluation (evaluation of color stripes) as in Example 1 were performed. The obtained results are shown in Table 1.

Example 20
Example 1 using the charging roller 1 and the photosensitive drum 1 similar to those in Example 1 except that the applied voltage was adjusted so that the photoreceptor surface potential (charging potential) was −200 V under the charging conditions of Example 1. The continuous printing test and image quality evaluation (evaluation of color stripes) were carried out in the same manner as above. The obtained results are shown in Table 1.

Example 21
Example 1 using the charging roller 4 and the photosensitive drum 1 similar to those in Example 10 except that the applied voltage was adjusted so that the photoreceptor surface potential (charging potential) was −200 V under the charging conditions of Example 10. The continuous printing test and image quality evaluation (evaluation of color stripes) were carried out in the same manner as above. The obtained results are shown in Table 1.

[Example 22]
Example 1 using the same charging roller 1 and photosensitive drum 1 as in Example 1 except that the applied voltage was adjusted so that the photoreceptor surface potential (charging potential) was −100 V under the charging conditions of Example 1. The continuous printing test and image quality evaluation (evaluation of color stripes) were carried out in the same manner as above. The obtained results are shown in Table 1.

Example 23
Example 1 using the charging roller 4 and the photosensitive drum 1 similar to those in Example 10 except that the applied voltage was adjusted so that the photoreceptor surface potential (charging potential) was −100 V under the charging conditions of Example 10. The continuous printing test and image quality evaluation (evaluation of color stripes) were carried out in the same manner as above. The obtained results are shown in Table 1.

Example 24
Example 1 using the same charging roller 1 and photosensitive drum 1 as in Example 1 except that the applied voltage was adjusted so that the photoreceptor surface potential (charging potential) was −400 V under the charging conditions of Example 1. The continuous printing test and image quality evaluation (evaluation of color stripes) were carried out in the same manner as above. The obtained results are shown in Table 1.

Example 25
Example 1 using the charging roller 4 and the photosensitive drum 1 similar to those in Example 10 except that the applied voltage was adjusted so that the photoreceptor surface potential (charging potential) was −400 V under the charging conditions of Example 10. The continuous printing test and image quality evaluation (evaluation of color stripes) were carried out in the same manner as above. The obtained results are shown in Table 1.

[Examples 26 to 27]
In Example 1, the continuous printing test and image quality evaluation were performed in the same manner as in Example 1 except that the absolute value of the difference between the charging potential and the developing potential was changed as shown in Table 1 by changing the surface potential of the developing roll. (Evaluation of color stripes) was performed. The obtained results are shown in Table 1.

[Examples 28 to 29]
In Example 10, the continuous printing test and image quality evaluation were performed in the same manner as in Example 1 except that the absolute value of the difference between the charging potential and the developing potential was changed as shown in Table 1 by changing the surface potential of the developing roll. (Evaluation of color stripes) was performed. The obtained results are shown in Table 1.

[Comparative Example 1]
A charging roller was prepared in the same manner as in Example 1 except that the ultraviolet irradiation treatment was not performed in Example 1. This was designated as a charging roller 8. Using the same photosensitive drum as in Example 1, the same continuous printing test and image quality evaluation (evaluation of color stripes) as in Example 1 were performed. The obtained results are shown in Table 1.

[Comparative Example 2]
Continuous printing test and image quality evaluation (evaluation of color streaks) as in Example 1 using the charging roller 8 manufactured in Comparative Example 1 and the same charging roller and photosensitive drum as the photosensitive drum 2 manufactured in Example 4 Carried out. The obtained results are shown in Table 1.

[Comparative Example 3]
Continuous printing test and image quality evaluation (evaluation of color streaks) similar to those in Example 1 using the charging roller 8 manufactured in Comparative Example 1 and the same charging roller and photosensitive drum as the photosensitive drum 3 manufactured in Example 7. Carried out. The obtained results are shown in Table 1.

[Comparative Example 4]
A charging roller was produced in the same manner as in Example 10 except that the ultraviolet irradiation treatment was not performed in Example 10. This was designated as a charging roller 9. Using the same photosensitive drum as in Example 1, the same continuous printing test and image quality evaluation (evaluation of color stripes) as in Example 1 were performed. The obtained results are shown in Table 1.

[Comparative Example 5]
Continuous printing test and image quality evaluation (evaluation of color streaks) as in Example 1 using the charging roller 9 manufactured in Comparative Example 4 and the same charging roller and photosensitive drum as the photosensitive drum 2 manufactured in Example 4. Carried out. The obtained results are shown in Table 1.

[Comparative Example 6]
Continuous printing test and image quality evaluation (evaluation of color streaks) as in Example 1 using the same charging roller and photosensitive drum as the charging roller 9 manufactured in Comparative Example 4 and the photosensitive drum 3 manufactured in Example 7. Carried out. The obtained results are shown in Table 1.

[Comparative Example 7]
Using the charging roller 8 prepared in Comparative Example 1 and the same charging roller and photosensitive drum as the photosensitive drum 1 manufactured in Example 1, application is made so that the surface potential of the photosensitive member is −200 V as in Example 20. A continuous printing test and image quality evaluation (evaluation of color stripes) were performed in the same manner as in Example 1 except that the voltage was adjusted. The obtained results are shown in Table 1.

[Comparative Example 8]
Using the same charging roller and photosensitive drum as the charging roller 9 manufactured in Comparative Example 4 and the photosensitive drum 1 manufactured in Example 1, application was made so that the surface potential of the photosensitive member was −200 V as in Example 20. A continuous printing test and image quality evaluation (evaluation of color stripes) were performed in the same manner as in Example 1 except that the voltage was adjusted. The obtained results are shown in Table 1.

[Comparative Example 9]
Using the charging roller 8 prepared in Comparative Example 1 and the charging roller and the photosensitive drum similar to the photosensitive drum 1 manufactured in Example 1, application is performed so that the surface potential of the photosensitive member is −400 V as in Example 22. A continuous printing test and image quality evaluation (evaluation of color stripes) were performed in the same manner as in Example 1 except that the voltage was adjusted. The obtained results are shown in Table 1.

[Comparative Example 10]
Using the charging roller 9 prepared in Comparative Example 4 and the same charging roller and photosensitive drum as those of the photosensitive drum 1 manufactured in Example 1, the surface potential of the photosensitive member is −400 V as in Example 22. A continuous printing test and image quality evaluation (evaluation of color stripes) were performed in the same manner as in Example 1 except that the voltage was adjusted. The obtained results are shown in Table 1.

  As shown in Table 1, in Examples 1 to 29 in which the charging roller surface was subjected to ultraviolet irradiation treatment, the color streaks in the formed image were compared with Comparative Examples 1 to 10 in which the charging roller surface was not irradiated with ultraviolet light. Was suppressed.

1 is a schematic view of an image forming apparatus according to an embodiment. It is the schematic of the image forming apparatus which concerns on other embodiment. It is a schematic perspective view of the charging roller in the present embodiment. FIG. 2 is a schematic diagram of a layer configuration of an image carrier (photosensitive drum) in the present embodiment. It is the schematic of the layer structure of the image holding body (photosensitive drum) in other embodiment. It is the schematic of the layer structure of the image holding body (photosensitive drum) in other embodiment. It is the schematic of the layer structure of the image holding body (photosensitive drum) in other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Undercoat layer 3 Photosensitive layer 4 Protective layer 5 Charge generation layer 6 Charge transport layer 30, 52 Photosensitive drum 31, 53 Charge roller 32 Power supply 33, 54 Exposure device 34, 55Y, 55M, 55C, 55K Developing device 35, 22 Transfer device 36, 80 Cleaning device 37 Static eliminating device (erase device)
38, 64 Fixing device 50 Image forming device 51Y Process cartridge (yellow)
51M process cartridge (magenta)
51C process cartridge (cyan)
51K process cartridge (black)
200 Charging roller (conductive elastic roller)
202 Ultraviolet irradiation light source 204 Shaft 206 Elastic layer 208 Surface layer

Claims (10)

An image carrier,
A charging roller having at least an elastic layer on the core, the surface being subjected to ultraviolet irradiation treatment, rotating in contact with the image carrier and charging the image carrier only with a DC voltage;
An image forming apparatus.   The image forming apparatus according to claim 1, wherein the image carrier has a photosensitive layer having a thickness of 20 μm to 40 μm on a conductive support.   The image forming apparatus according to claim 1, wherein the charging roller further has a surface layer on the elastic layer.   The image forming apparatus according to claim 1, wherein the charging roller charges the image holding member to a potential of −100 V or less. Furthermore, latent image forming means for forming a latent image on the surface of the image carrier charged by the charging roller, and development for forming a toner image by developing the latent image formed on the surface of the image carrier with toner. Means,
5. The image forming apparatus according to claim 1, wherein an absolute value of a difference between the potential of the image holding member charged by the charging roller and the potential of the developing unit is 30 V or less. . An image carrier,
A charging roller having at least an elastic layer on the core, the surface being subjected to ultraviolet irradiation treatment, rotating in contact with the image carrier and charging the image carrier only with a DC voltage;
A process cartridge.   The process cartridge according to claim 6, wherein the image carrier has a photosensitive layer having a thickness of 20 μm to 40 μm on a conductive support.   The process cartridge according to claim 6, wherein the charging roller further has a surface layer on the elastic layer.   The process cartridge according to any one of claims 6 to 8, wherein the charging roller charges the image carrier to a potential of -100V or less. Furthermore, latent image forming means for forming a latent image on the surface of the image carrier charged by the charging roller, and development for forming a toner image by developing the latent image formed on the surface of the image carrier with toner. Means,
10. The process cartridge according to claim 6, wherein an absolute value of a difference between the potential of the image holding member charged by the charging roller and the potential of the developing unit is 30 V or less.

Images