JP2007264254A - Charging member and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact type charging member whose surface is sufficiently low in stickiness, which prevents sticking of toner and additives to its surface, and from which stable and good uniform charging characteristics and output image quality can be obtained and to provide an electrophotographic apparatus provided with the charging member. <P>SOLUTION: The charging member is provided with at least a conductive supporting member 1a, a conductive elastic body layer 1b formed on the conductive supporting member 1a, a base layer 1c formed on the conductive elastic body layer and a surface layer 1d. In the charging member, the surface layer is formed by coating liquid containing at least one type of polymer selected from acrylic fluoride-based polymer and acrylic silicone-based polymer, and at least polyol and poly isocyanate and has a film thickness of 50nm to 2μm. Alternatively, the surface layer contains conductors but the film thickness is not restricted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charging member and an electrophotographic apparatus using the charging member, and more specifically, a charged member is charged by bringing a charged member to which a voltage is applied into contact with the charged member (photosensitive drum). The present invention relates to a charging member and an electrophotographic apparatus having the charging member.

  Many methods are known as an electrophotographic apparatus. Generally, a photoconductive substance is used to form an electric latent image on a photosensitive member by various means, and then the latent image is developed with toner. A visible image is formed, and a toner image is transferred onto a transfer material such as paper as necessary. Then, the toner image is fixed on the transfer material by heat, pressure or the like to obtain a copy. In addition, toner particles that are not transferred onto the transfer material but remain on the photoconductor are removed from the photoconductor by a cleaning process.

  Conventionally, a corona charger has been used as a charging processing device for an electrophotographic apparatus. In recent years, contact charging devices have been put to practical use instead. This is intended for low ozone and low power consumption, and among these, a roll charging method using a conductive roll as a charging member is particularly preferably used from the viewpoint of charging stability. In roll charging, a conductive elastic roll is brought into pressure contact with a member to be charged, and a voltage is applied thereto to charge the member to be charged. As a conductive member for charging, there is an example in which a surface layer is formed by a conductive seamless tube on a conductive support member (see, for example, Patent Document 1). A multilayer tube having a layer configuration with different conductivity is also disclosed (for example, see Patent Document 2).

  As a method related to manufacture as a charging member, a method of forming by insertion is mentioned as the conventional technique.

  In such a method of forming the charging roll with the seamless tube, even if a foam is used as the elastic layer on the conductive support member, a smooth surface can be formed by further covering it with the seamless tube. This makes it easier to perform more uniform charging.

  However, regarding contact-type charging members, if toner and external additives easily adhere to the surface of the charging member, the resistance value changes or varies due to adhesion to the surface of the charging member, resulting in stable and good uniform charging characteristics and output. It has been difficult to provide a charging member that obtains image quality. Conventionally, as a means for solving this problem, a method of reducing the surface roughness has been proposed (see, for example, Patent Document 3).

However, in the case of a charging member made of a seamless tube based on a thermoplastic elastomer as a surface layer, the surface of the charging member is contaminated simply by reducing the surface roughness and smoothing it because it is soft and sticky in characteristics. It was difficult to improve the performance.
US Pat. No. 4,967,231 Japanese Patent Laid-Open No. 5-96648 JP 2000-137369 A

  The present invention has been made in view of the above-mentioned problems, and relates to a contact-type charging member. The surface of the member has a sufficiently low adhesion, prevents adhesion of toner and external additives to the surface of the member, and is stable and stable. It is an object of the present invention to provide a charging member capable of obtaining good uniform charging characteristics and output image quality, and an electrophotographic apparatus having the charging member.

  The present invention is as follows.

  (1) In a charging member having at least a conductive support member, a conductive elastic layer formed on the conductive support member, a base layer formed on the conductive elastic layer, and a surface layer The surface layer has a film thickness of 50 nm or more and 2 μm or less formed of a coating solution containing at least one polymer selected from an acrylic fluorine-based polymer and an acrylic silicone-based polymer, and a polyol and a polyisocyanate. A charging member which is a layer.

  (2) The charging member according to (1), wherein the base layer is a seamless tube formed by an extruder.

  (3) The charging member according to (1) or (2) (hereinafter referred to as “first”), wherein the surface layer is a surface layer mainly composed of an acrylic urethane resin obtained by crosslinking an acrylic polyol with an isocyanate. Of the present invention).

(4) The electrophotographic apparatus is characterized in that the charging means is the charging member according to any one of (1) to (3).
(5) In a charging member having at least a conductive support member, a conductive elastic layer formed on the conductive support member, a base layer formed on the conductive elastic layer, and a surface layer The surface layer is a surface layer formed of a coating solution containing at least one polymer selected from an acrylic fluorine-based polymer and an acrylic silicone-based polymer, a polyol, a polyisocyanate, and a conductive agent. The charging member (hereinafter referred to as “second invention”).
(6) The charging member according to (5), wherein the base layer is a seamless tube formed by an extruder.
(7) The charging member according to (5) or (6), wherein the surface layer is a surface layer mainly composed of an acrylic urethane resin obtained by crosslinking an acrylic polyol with an isocyanate.
(8) An electrophotographic apparatus, wherein the charging means is the charging member according to any one of claims (5) to (7).

  The “first invention” and the “second invention” are collectively referred to as “the present invention”.

  According to the present invention, it is possible to provide a charging member in which the toner and the external additive are hardly attached to the surface and the resistance value hardly changes. If the charging member of the present invention is used in an electrophotographic apparatus, stable and good uniform charging characteristics and output image quality can be provided.

  Hereinafter, embodiments of the present invention will be described in detail.

<1> Charging member of the present invention The charging member of the first present invention is formed on a conductive support member, a conductive elastic layer formed on the conductive support member, and the conductive elastic layer. A charging member having at least an undercoat layer and a surface layer, wherein the surface layer contains at least one polymer selected from an acrylic fluorine-based polymer and an acrylic silicone-based polymer, at least a polyol and a polyisocyanate. It is a surface layer having a film thickness of 50 nm or more and 2 μm or less formed of a liquid.

  The charging member according to the second aspect of the present invention includes a conductive support member, a conductive elastic layer formed on the conductive support member, a base layer formed on the conductive elastic layer, and a surface layer. The surface layer is formed of a coating solution containing at least one polymer selected from an acrylic fluorine-based polymer and an acrylic silicone-based polymer, a polyol, a polyisocyanate, and a conductive agent. It is a surface layer.

  A specific configuration example of the charging member of the present invention is shown in FIGS. FIG. 1 shows a transverse section of the charging member, and FIG. 2 shows a longitudinal section. The charging member of the present invention is a charging member having a conductive support member 1a, a conductive elastic layer 1b formed on the outer periphery thereof, a base layer 1c formed on the outer periphery thereof, and an outermost surface layer 1d.

  The conductive support member 1a used in the present invention is made of a metal such as iron, aluminum, titanium, copper and nickel, an alloy such as stainless steel, duralumin, brass and bronze containing these metals, or carbon black or carbon fiber made of plastic. It is also possible to use known materials that are rigid and exhibit electrical conductivity, such as hardened composite materials. In addition to the columnar shape, the shape may be a cylindrical shape with a central portion as a cavity. In addition, these surfaces may be plated for the purpose of rust prevention or scratch resistance.

  Specific examples of the conductive elastic layer 1b used in the present invention include natural rubber, chloroprene rubber (CR), isoprene rubber (IR), ethylene propylene rubber (EPDM), styrene butadiene rubber (SBR), urethane rubber, epichlorohydrin. It can be formed of rubber such as rubber, epoxy rubber and butyl rubber or sponge. A conductive agent having an electronic conductive mechanism such as carbon black, graphite and a conductive metal oxide, and a conductive agent having an ionic conductive mechanism such as an alkali metal salt or a quaternary ammonium salt can be appropriately added to these rubbers.

  Specifically, the base layer 1c used in the present invention includes olefin (TPO), styrene (TPS), urethane (TPU), ester (TPEE), amide (TPA), and vinyl chloride (PVC). And thermoplastic elastomers. Next, as a method for producing the underlayer, first, a conductive pigment such as thermoplastic elastomer and carbon black is kneaded together with necessary additives, and then pelletized. Next, the obtained pellet is made into a seamless tube by an extrusion molding machine. Then, the molded seamless tube is covered with a conductive support member to form a conductive member. Moreover, it does not restrict | limit at all to set it as a multilayer simultaneous forming tube.

  The surface layer 1d used in the present invention is formed of a coating solution containing at least one polymer selected from an acrylic fluorine-based polymer and an acrylic silicone-based polymer, a polyol and a polyisocyanate.

  The acrylic fluoropolymer and the acrylic silicone polymer can be chemically bonded by reacting with an isocyanate compound, and are, for example, polymers having a hydroxyl group, an alkyl group, a carboxyl group, and the like.

  Specific examples of the acrylic fluoropolymer include block copolymers of methacrylic acid esters and fluorinated alkyl acrylates and derivatives thereof.

  Specific examples of the acrylic silicone-based polymer include block copolymers of methacrylic acid esters and methacrylic acid polysiloxane esters and derivatives thereof.

  Specific examples of the polyol include polyether polyols such as polyoxytetraethylene glycol, polyoxytetramethylene glycol, and polyoxypropylene glycol, polycaprolactone, and derivatives thereof (acrylic modification).

  Specifically, any polyisocyanate may be used as long as it is a compound having two or more isocyanate groups in the molecule. However, since it is easy to handle and a high-quality coating film can be obtained, the MDI ( Diphenylmethane-4,4′-diisocyanate), HDI (hexamethylene diisocyanate), and derivatives thereof are preferably used.

  In the first aspect of the present invention, when the film thickness of the surface layer is larger than 2 μm, the image is crumpled or blackened due to charging failure. Further, if the thickness of the surface layer is smaller than 50 nm, there is a problem with the durability of the surface layer. If continuous printing of a plurality of images is continued, the image will be fuzzy or blackened due to member contamination. . Therefore, the film thickness of the surface layer is 50 nm or more and 2 μm or less. Preferably, it is 100 nm or more and 1 μm or less.

  In the second invention, the coating liquid for forming the surface layer contains a conductive agent. The conductive agent is not particularly limited, but conductive carbon such as ketjen black EC and acetylene black, rubber carbon such as SAF, ISAF, HAF, MAF, FEF, GPF, SRF, FT and MT, oxidation Treated color ink carbon, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium and other metals or metal oxides may be used. it can. The surface of the conductive agent is a coupling agent such as a titanium coupling agent or an alkoxysilane coupling agent, and a coupling agent such as a fluoroalkylalkoxysilane coupling agent (a central metal such as silicon, titanium, aluminum and zirconium is not particularly selected). Or may be treated with oil, varnish, organic compound or the like. Moreover, the addition amount of the said electrically conductive agent can be suitably adjusted so that desired resistance may be obtained.

  As a method for forming the surface layer, the material constituting the surface layer was obtained by dispersing by a known method using a conventionally known dispersion apparatus using beads such as a sand mill, paint shaker, dyno mill, pearl mill, etc. A resin coating for forming the surface layer is applied by dipping, spray coating, or ring coating on the surface of the charging member, in the present invention, on the conductive seamless tube that is the underlayer. In consideration of the utilization efficiency of the resin paint, the ring coat method is preferable.

  FIG. 3 shows a schematic diagram of the ring coating method, and FIG. 4 shows a schematic diagram of a ring coating (coating) head.

  As shown in the drawing, the conductive roller 2a is supported vertically (2b, 2c), and a slit-like discharge port 3a that is opened at a predetermined distance from the conductive roller 2a, and a ring By the coating material supply means (2e, 2f) outside the coating head 2d, the resin coating material supplied from the liquid supply port 3b provided in the ring coating head 2d is merged in the ring coating head 2d in the circumferential direction. The conductive roller 2a and the ring coating head 2d are moved relative to each other at a predetermined speed by a cylindrical coating head (ring coating head) 2d having a liquid distribution chamber 3c for distribution, and the surface of the conductive roller 2a is desired. In accordance with the coating film thickness, only a suitable amount of resin coating is supplied uniformly over the entire circumference and discharged onto the surface of the conductive roller to form a thin film layer. Moreover, the discharge amount to the surface of the conductive roller is calculated by the ratio of the desired coating film thickness and the solid content of the resin paint. In the figure, 2g is a motor, 2h is a pulley and belt, 2i is a ball screw, 2j is a slide guide, 2k is an LM guide, and 2l is a bracket.

<2> Electrophotographic apparatus of the present invention The present invention is also an electrophotographic apparatus using the charging member of the present invention.

  The electrophotographic photoreceptor, exposure means, development means, transfer means and cleaning means used in the present invention are not particularly limited. FIG. 5 shows an example in which the charging member of the present invention is applied to an electrophotographic apparatus. A rotating drum type electrophotographic photosensitive member (photosensitive member) 21 as an image carrier is rotationally driven at a predetermined peripheral speed (process speed) in a direction indicated by an arrow in the figure. As the photoreceptor 21, for example, a known photoreceptor having at least a roll-like conductive support and a photosensitive layer containing an inorganic photosensitive material or an organic photosensitive material on the support may be employed. The photoconductor 21 may further include a charge injection layer for charging the surface of the photoconductor to a predetermined polarity or potential. The charging roller (conductive roller) 22 as a charging member includes a charging unit including a charging roller and a charging bias application power source S1 that applies a charging bias to the charging roller. The charging roller 22 is brought into contact with the photosensitive member 21 with a predetermined pressing force, and is rotated in the forward direction with respect to the rotation of the photosensitive member 21 in this example. By applying a predetermined voltage from the charging bias applying power source S1 to the charging roller 22, the surface of the photoconductor 21 is uniformly charged to a predetermined polarity potential. A known means can be used as the exposure means 23. For example, a laser beam scanner or the like can be preferably exemplified. The exposure means 23 performs exposure L corresponding to the target image information on the charging surface of the photosensitive member 21, whereby the potential of the exposed bright portion of the photosensitive member charging surface is selectively reduced (decayed). An electrostatic latent image is formed at 21. As the developing unit 24, a known unit can be used. For example, the developing unit 24 in this example is provided in a toner container 24 a that is disposed in an opening of a developing container that stores toner and carries and transports toner. The agitating member 24b for agitating the toner that has been used, and the toner regulating member 24c for regulating the toner carrying amount (toner layer thickness) of the toner carrying member 24a. The developing unit 24 selectively attaches toner (negative toner) charged to the same polarity as the charged polarity of the photosensitive member 21 to the exposed bright portion of the electrostatic latent image on the surface of the photosensitive member 21 to form the electrostatic latent image. Visualize as a toner image. There is no particular limitation on the development method, and all existing methods can be used. Examples of existing methods include a jumping development method, a contact development method, and a magnetic brush method. As the transfer roller 25 as the transfer means, a known means can be used, for example, a transfer roller or the like formed by coating a conductive support such as metal with an elastic resin layer adjusted to a medium resistance. Can do. The transfer roller 25 is brought into contact with the photoconductor 21 with a predetermined pressing force to form a transfer nip portion, and rotates in the forward direction with the rotation speed of the photoconductor 21 at substantially the same peripheral speed as the rotation speed of the photoconductor 21. . Further, a transfer voltage having a polarity opposite to the charging characteristics of the toner is applied from the transfer bias application power source S2. A transfer material P is fed to a transfer nip portion from a sheet feeding mechanism (not shown) at a predetermined timing, and the back surface of the transfer material P is opposite to the charging polarity of toner by a transfer roller 5 to which a transfer voltage is applied. By being charged to polarity, the toner image on the surface of the photoreceptor 21 is electrostatically transferred to the surface side of the transfer material P at the transfer nip portion. The transfer material P that has received the transfer of the toner image at the transfer nip portion is separated from the surface of the photosensitive member, is introduced into a toner image fixing unit (not shown), receives the toner image, and is output as an image formed product. In the case of the double-sided image forming mode or the multiple image forming mode, the image formed product is introduced into a recirculation conveyance mechanism (not shown) and reintroduced into the transfer nip portion. Residues on the photosensitive member 21 such as transfer residual toner are collected from the photosensitive member by a cleaning means 26 such as a blade type. In the case where residual charge remains on the photosensitive member 21, it is preferable to remove the residual charge on the photosensitive member 21 by the pre-exposure means 27 before the primary charging by the charging member 22.

  Hereinafter, the present invention will be described in more detail using specific examples. However, the present invention is not limited to these. In the examples, “part” means part by mass, and “%” means mass%.

Example 1
[Preparation of conductive elastic layer]
EPDM 100 parts, zinc oxide 5 parts, higher fatty acid 1 part, conductive carbon black 5 parts, paraffin oil 10 parts, sulfur 2 parts, vulcanization accelerator (MBT) 1 part, vulcanization accelerator (TMTD) 1 part, A compound was prepared by mixing 1.5 parts of a vulcanization accelerator (ZnMDC) and 10 parts of a foaming agent (sodium bicarbonate) with two rolls for 20 minutes. This was extruded into a cylindrical shape with an outer diameter of 13 mm and an inner diameter of 5.5 mm using a rubber extruder, cut into a length of 250 mm, and primary for 40 minutes in steam at 160 ° C. using a vulcanizing can. Vulcanized to obtain a primary vulcanized tube of conductive elastic layer rubber. Next, a thermosetting adhesive (trade name: metal and rubber) is attached to the central portion 231 mm in the axial direction of the cylindrical surface of a cylindrical conductive support member (steel, surface industrial nickel plating) having a diameter of 6 mm and a length of 256 mm. Metallock U-20) was applied, dried at 80 ° C. for 30 minutes, and then dried at 120 ° C. for 1 hour. This conductive support member is inserted into the conductive elastic layer rubber primary vulcanization tube, and then subjected to secondary vulcanization and curing of the adhesive in an electric oven at 160 ° C. for 2 hours. A layer was obtained. After cutting off both ends of the rubber part of this unpolished layer and setting the length of the rubber part to 231 mm, the rubber part is polished with a rotating grindstone to form a crown shape having an end diameter of 11.30 mm and a central part diameter of 11.50 mm. A foam roller having a conductive elastic layer was obtained.

[Creation of underlayer]
For the conductive seamless tube formed on the foaming roller, 15 parts of Ketjen Black EC, 10 parts of magnesium oxide and 1 part of calcium stearate are added to 100 parts of thermoplastic polyurethane elastomer (TPU), and 180 parts using a pressure kneader. The mixture was kneaded at 15 ° C. for 15 minutes, cooled and pulverized, and pelletized by a granulator extruder. Using the above pellets, after extrusion with an extruder equipped with a point with an outer diameter of φ16.70 mm and a die with an inner diameter of φ18.50 mm, through a sizing and cooling process, the outer diameter φ11.90 mm, the inner diameter φ11.10 mm, It was molded into a seamless tube having a thickness of 400 μm and cut into a length of 300 mm. The obtained seamless tube is covered with a foaming roller having the conductive elastic body layer, both ends are cut off, the length of the seamless tube portion is 234 mm, the end diameter is 11.95 mm, and the center diameter is 12.00 mm. A conductive roller having a shaped underlayer was obtained.

(Creation of surface layer)
A surface layer as shown below was applied and formed on the conductive roller.

  As a material for the surface layer, 100 parts of a lactone-modified acrylic polyol (solid content 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) is dissolved in 2781 parts of methyl isobutyl ketone, and blocked isocyanate (IPDI) ( Solid content 60%, trade name "Duranate MF-K60X": 125 parts by Asahi Kasei Chemicals Co., Ltd., acrylic silicone polymer (solid content 15%, trade name "Modiper FS710": Nippon Oil & Fats Co., Ltd.) 48 parts Then, 0.2 part of modified dimethyl silicone oil (trade name “SH-28PA”: manufactured by Toray Dow Corning Silicone Co., Ltd.) was blended and dispersed for 6 hours using a paint shaker to prepare a resin paint. The solid content of this resin paint was 5%. The surface layer forming coating solution was applied to the surface of the conductive roller by a ring coating method so that the film thickness before drying was 8 μm. After air drying for 30 minutes, it was sintered and dried at 110 ° C. for 60 minutes. In this way, a roller-shaped charging member having a 400 nm surface layer coated thereon was obtained.

<Endurance test for charging multiple continuous images of charging rollers>
The charging member obtained as described above was mounted on a printer, and an endurance test for continuously printing a plurality of images was performed in an atmosphere at a temperature of 23 ° C. and a humidity of 55%. Monocolor halftone printing was performed on the initial, 10,000, 20,000 and 50,000 sheets. The obtained image was visually observed and evaluated. The results are shown in Table 1.

  “◎”, “◯”, “Δ”, and “×” in the table are the image quality ranks classified into four levels for the occurrence of charging unevenness. In addition, “」 ”is a level where there is no charging unevenness, and“ ◯ ”is good. “Δ” and “×” are determined to be NG because they have some image problem portions which are inferior as a product.

  The charging member of Example 1 did not cause uneven charging before and after endurance, and maintained good charging uniformity even after endurance.

(Example 2)
In the preparation of the surface layer of Example 1, as a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) and 2582 parts of methyl isobutyl ketone Dissolved in water, blocked isocyanate (IPDI) (solid content 60%, trade name “Duranate MF-K60X”: manufactured by Asahi Kasei Chemicals Corporation) 106 parts, acrylic fluoropolymer (solid content 30%, trade name “Modiper F200” : Nippon Oil & Fats Co., Ltd.) 22 parts, modified dimethyl silicone oil (trade name “SH-28PA”: Toray Dow Corning Silicone Co., Ltd.) 0.2 part, blended for 6 hours using a paint shaker Dispersed to create a resin paint. The solid content of this resin paint was 5%. The surface layer forming coating solution was applied to the surface of the conductive roller by a ring coating method so that the film thickness before drying was 8 μm. After air drying for 30 minutes, it was sintered and dried at 110 ° C. for 60 minutes. In this way, a roller-shaped charging member having a 400 nm surface layer coated thereon was obtained.

  This charging member was also subjected to a continuous plural-sheet image endurance test in the same manner as in Example 1. The results are shown in Table 1.

  The charging member of Example 2 did not cause uneven charging before and after endurance, and maintained good charging uniformity even after endurance.

(Example 3)
In preparation of the surface layer of Example 1, as a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) and 27,900 parts of methyl isobutyl ketone Dissolved in water, blocked isocyanate (IPDI) (solid content 60%, trade name “Duranate MF-K60X”: manufactured by Asahi Kasei Chemicals Corporation) 106 parts, acrylic fluoropolymer (solid content 30%, trade name “Modiper F200” : Nippon Oil & Fats Co., Ltd.) 22 parts, modified dimethyl silicone oil (trade name “SH-28PA”: Toray Dow Corning Silicone Co., Ltd.) 0.2 part, blended for 6 hours using a paint shaker Dispersed to create a resin paint. The solid content of this resin coating was 0.5%. The surface layer forming coating solution was applied on the surface of the conductive roller by a ring coating method so that the film thickness before drying was 10 μm. After air drying for 30 minutes, it was sintered and dried at 110 ° C. for 60 minutes. Thus, a roller-shaped charging member having a 50 nm surface layer applied and formed was obtained.

  This charging member was also subjected to a continuous plural-sheet image endurance test in the same manner as in Example 1. The results are shown in Table 1.

  In the initial stage, the charging member of Example 3 was 10000 sheets in the endurance, and the charging unevenness did not occur and good charging uniformity was maintained. After 20000 sheets during the durability, slight charging unevenness that seems to be caused by the durability of the surface layer occurred, but the image quality had no problem in practical use.

Example 4
In preparation of the surface layer of Example 1, as a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) and 474 parts of methyl isobutyl ketone Dissolved in water, blocked isocyanate (IPDI) (solid content 60%, trade name “Duranate MF-K60X”: manufactured by Asahi Kasei Chemicals Corporation) 106 parts, acrylic fluoropolymer (solid content 30%, trade name “Modiper F200” : Nippon Oil & Fats Co., Ltd.) 22 parts, modified dimethyl silicone oil (trade name “SH-28PA”: Toray Dow Corning Silicone Co., Ltd.) 0.2 part, blended for 6 hours using a paint shaker Dispersed to create a resin paint. The resin paint had a solid content of 20%. The surface layer forming coating solution was applied on the surface of the conductive roller by a ring coating method so that the film thickness before drying was 10 μm. After air drying for 30 minutes, it was sintered and dried at 110 ° C. for 60 minutes. Thus, a roller-shaped charging member having a surface layer of 2 μm applied and formed was obtained.

  This charging member was also subjected to a continuous plural-sheet image endurance test in the same manner as in Example 1. The results are shown in Table 1.

  The charging member of Example 4 had slight charging unevenness that was attributed to the thickness of the surface layer before and after endurance, but the image quality had no problem in practical use.

(Comparative Example 1)
In the preparation of the surface layer of Example 1, as a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) and 2314 parts of methyl isobutyl ketone Dissolved in water, blocked isocyanate (IPDI) (solid content 60%, trade name "Duranate MF-K60X": manufactured by Asahi Kasei Chemicals Corporation) 92 parts, modified dimethyl silicone oil (trade name "SH-28PA": Toray Dow 0.2 parts of Corning Silicone Co., Ltd. was blended and dispersed for 6 hours using a paint shaker to prepare a resin paint. The solid content of this resin paint was 5%. The surface layer forming coating solution was applied to the surface of the conductive roller by a ring coating method so that the film thickness before drying was 8 μm. After air drying for 30 minutes, it was sintered and dried at 110 ° C. for 60 minutes. In this way, a roller-shaped charging member having a 400 nm surface layer coated thereon was obtained.

  This charging member was also subjected to a continuous plural-sheet image endurance test in the same manner as in Example 1. The results are shown in Table 2.

  The charging member of Comparative Example 1 had good image quality with no occurrence of charging unevenness in the initial stage. However, slight charging unevenness due to member contamination occurred in 20000 sheets during durability, and further deteriorated after further durability. did.

(Comparative Example 2)
In preparation of the surface layer of Example 1, as a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) and 27,900 parts of methyl isobutyl ketone Dissolved in water, blocked isocyanate (IPDI) (solid content 60%, trade name “Duranate MF-K60X”: manufactured by Asahi Kasei Chemicals Corporation) 106 parts, acrylic fluoropolymer (solid content 30%, trade name “Modiper F200” : Nippon Oil & Fats Co., Ltd.) 22 parts, modified dimethyl silicone oil (trade name “SH-28PA”: Toray Dow Corning Silicone Co., Ltd.) 0.2 part, blended for 6 hours using a paint shaker Dispersed to create a resin paint. The solid content of this resin coating was 0.5%. The surface layer forming coating solution was applied to the surface of the conductive roller by a ring coating method so that the film thickness before drying was 6 μm. After air drying for 30 minutes, it was sintered and dried at 110 ° C. for 60 minutes. In this way, a roller-shaped charging member having a 30 nm surface layer applied and formed was obtained.

  This charging member was also subjected to a continuous plural-sheet image endurance test in the same manner as in Example 1. The results are shown in Table 2.

  In the initial stage, the charging member of Comparative Example 2 was free from uneven charging and maintained good charging uniformity. Minor charging unevenness caused by the durability of the surface layer occurred at 10,000 sheets during the durability, and was further deteriorated after further durability.

(Comparative Example 3)
In preparation of the surface layer of Example 1, as a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) and 474 parts of methyl isobutyl ketone Dissolved in water, blocked isocyanate (IPDI) (solid content 60%, trade name “Duranate MF-K60X”: manufactured by Asahi Kasei Chemicals Corporation) 106 parts, acrylic fluoropolymer (solid content 30%, trade name “Modiper F200” : Nippon Oil & Fats Co., Ltd.) 22 parts, modified dimethyl silicone oil (trade name “SH-28PA”: Toray Dow Corning Silicone Co., Ltd.) 0.2 part, blended for 6 hours using a paint shaker Dispersed to create a resin paint. The resin paint had a solid content of 20%. The surface layer forming coating solution was applied to the surface of the conductive roller by a ring coating method so that the film thickness before drying was 15 μm. After air drying for 30 minutes, it was sintered and dried at 110 ° C. for 60 minutes. Thus, a roller-shaped charging member having a 3 μm surface layer applied and formed was obtained.

  This charging member was also subjected to a continuous plural-sheet image endurance test in the same manner as in Example 1. The results are shown in Table 2.

  The charging member of Comparative Example 3 had uneven charging before and after endurance, which seems to be caused by the thickness of the surface layer.

(Example 5)
[Preparation of conductive elastic layer]
EPDM 100 parts, zinc oxide 5 parts, higher fatty acid 1 part, conductive carbon black 5 parts, paraffin oil 10 parts, sulfur 2 parts, vulcanization accelerator (MBT) 1 part, vulcanization accelerator (TMTD) 1 part, A compound was prepared by mixing 1.5 parts of a vulcanization accelerator (ZnMDC) and 10 parts of a foaming agent (sodium bicarbonate) with two rolls for 20 minutes. This was extruded into a cylindrical shape with an outer diameter of 13 mm and an inner diameter of 5.5 mm using a rubber extruder, cut into a length of 250 mm, and primary for 40 minutes in steam at 160 ° C. using a vulcanizing can. Vulcanized to obtain a primary vulcanized tube of conductive elastic layer rubber. Next, a thermosetting adhesive (trade name: metal and rubber) is attached to the central portion 231 mm in the axial direction of the cylindrical surface of a cylindrical conductive support member (steel, surface industrial nickel plating) having a diameter of 6 mm and a length of 256 mm. Metallock U-20) was applied, dried at 80 ° C. for 30 minutes, and then dried at 120 ° C. for 1 hour. This conductive support member is inserted into the conductive elastic layer rubber primary vulcanization tube, and then subjected to secondary vulcanization and curing of the adhesive in an electric oven at 160 ° C. for 2 hours. A layer was obtained. After cutting off both ends of the rubber part of this unpolished layer and setting the length of the rubber part to 231 mm, the rubber part is polished with a rotating grindstone to form a crown shape having an end diameter of 11.30 mm and a central part diameter of 11.50 mm. A foam roller having a conductive elastic layer was obtained.

[Creation of underlayer]
For the conductive seamless tube formed on the foamed roller, 16 parts of Ketjen Black EC, 10 parts of magnesium oxide and 1 part of calcium stearate are added to 100 parts of thermoplastic polyurethane elastomer (TPU), and 180 parts using a pressure kneader. The mixture was kneaded at 15 ° C. for 15 minutes, cooled and pulverized, and pelletized by a granulator extruder. Using the above pellets, after extrusion with an extruder equipped with a point with an outer diameter of φ16.70 mm and a die with an inner diameter of φ18.50 mm, through a sizing and cooling process, the outer diameter φ11.90 mm, the inner diameter φ11.10 mm, It was molded into a seamless tube having a thickness of 400 μm and cut into a length of 300 mm. The obtained seamless tube is covered with a foaming roller having the conductive elastic body layer, both ends are cut off, the length of the seamless tube portion is 234 mm, the end diameter is 11.95 mm, and the center diameter is 12.00 mm. A conductive roller having a shaped underlayer was obtained.

(Creation of surface layer)
A surface layer as shown below was applied and formed on the conductive roller.

  As a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) is dissolved in 78 parts of methyl isobutyl ketone, and blocked isocyanate (IPDI) ( Solid content 60%, trade name "Duranate MF-K60X": Asahi Kasei Chemicals Corporation 129 parts, acrylic silicone polymer (solid content 15%, trade name "Modiper FS710": Nippon Oil & Fats Co., Ltd.) 53 parts , 12 parts of carbon black (trade name “MA100”: manufactured by Mitsubishi Chemical Corporation), 0.2 parts of modified dimethyl silicone oil (trade name “SH-28PA”: manufactured by Toray Dow Corning Silicone Co., Ltd.) A resin paint was prepared by dispersing for 6 hours using a paint shaker. The resin paint had a solid content of 45%. The surface layer forming coating solution was applied to the surface of the conductive roller by a ring coating method so that the film thickness before drying was 22 μm. After air drying for 30 minutes, it was sintered and dried at 110 ° C. for 60 minutes. Thus, a roller-shaped charging member having a 10 μm surface layer applied and formed was obtained.

<Endurance test for charging multiple continuous images of charging rollers>
The charging member obtained as described above was mounted on a printer, and an endurance test for continuously printing a plurality of images was performed in an atmosphere at a temperature of 23 ° C. and a humidity of 55%. Monocolor halftone printing was performed on the initial, 10,000, 20,000 and 50,000 sheets. The obtained image was visually observed and evaluated. The results are shown in Table 3.

  In the table, “◎”, “◯”, “Δ”, “×”, “XX” are image quality ranks classified into five levels with respect to the occurrence of charging unevenness. In addition, “」 ”is a level where there is no charging unevenness, and“ ◯ ”is good. “Δ” and “×” are determined to be NG because they have some image problem portions which are inferior as a product. Furthermore, “XX” was determined to be a defective level because of uneven charging. The results are shown in Table 3.

  The charging member of Example 5 was free from uneven charging before and after endurance and maintained good charging uniformity after endurance.

(Example 6)
In preparation of the surface layer of Example 5, as a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content: 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) and 98 parts of methyl isobutyl ketone Dissolved in water, 107 parts of blocked isocyanate (IPDI) (solid content 60%, trade name “Duranate MF-K60X” manufactured by Asahi Kasei Chemicals Corporation), acrylic fluoropolymer (solid content 30%, trade name “Modiper F200”) : Nippon Oil & Fats Co., Ltd.) 24 parts, Carbon Black (trade name “MA100”: Mitsubishi Chemical Co., Ltd.) 11 parts, Modified dimethyl silicone oil (trade name “SH-28PA”: Toray Dow Corning Silicone Co., Ltd.) ) Made) 0.2 parts. Otherwise, a charging member was obtained in the same manner as in Example 5.

  This charging member was also subjected to a continuous plural-sheet image endurance test in the same manner as in Example 5. The results are shown in Table 3.

  The charging member of Example 6 did not cause uneven charging before and after endurance, and maintained good charging uniformity even after endurance.

(Comparative Example 4)
In preparation of the surface layer of Example 5, as a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) 99 parts of methyl isobutyl ketone Dissolved in water, blocked isocyanate (IPDI) (solid content 60%, trade name “Duranate MF-K60X”: manufactured by Asahi Kasei Chemicals) 92 parts carbon black (trade name “MA100”: manufactured by Mitsubishi Chemical Corporation) 10 parts and 0.2 parts of modified dimethyl silicone oil (trade name “SH-28PA” manufactured by Toray Dow Corning Silicone Co., Ltd.) were blended. Otherwise, a charging member was obtained in the same manner as in Example 5.

  This charging member was also subjected to a continuous plural-sheet image endurance test in the same manner as in Example 5. The results are shown in Table 3.

  The charging member of Comparative Example 4 had good image quality with no occurrence of charging unevenness before endurance. However, uneven charging occurred with 20000 sheets during endurance, and deteriorated after further endurance.

(Comparative Example 5)
In Example 5, the conductive roller obtained by covering the conductive seamless tube without forming the surface layer was used as the charging member of Comparative Example 5.

  This charging member was also subjected to a continuous plural-sheet image endurance test in the same manner as in Example 5. The results are shown in Table 3.

  The charging member of Comparative Example 5 had good image quality with no occurrence of charging unevenness before endurance. However, uneven charging occurred with 10,000 sheets during endurance and was further deteriorated after further endurance.

(Comparative Example 6)
In preparation of the surface layer of Example 5, as a material for the surface layer, 100 parts of lactone-modified acrylic polyol (solid content: 70%, trade name “Placcel DC2016” manufactured by Daicel Chemical Industries, Ltd.) and 87 parts of methyl isobutyl ketone Dissolved in water, blocked isocyanate (IPDI) (solid content 60%, trade name "Duranate MF-K60X": manufactured by Asahi Kasei Chemicals Corporation) 92 parts, modified dimethyl silicone oil (trade name "SH-28PA": Toray Dow 0.2 part of Corning Silicone Co., Ltd. was blended. Otherwise, a charging member was obtained in the same manner as in Example 5.

  This charging member was also subjected to an image output test in the same manner as in Example 5. The results are shown in Table 3.

  The charging member of Comparative Example 6 was fogged from the beginning, and could not be subjected to continuous endurance printing.

FIG. 3 is a schematic cross-sectional view showing a configuration of a charging member of the present invention. It is a schematic longitudinal cross-sectional view which shows the structure of the charging member of this invention. It is the schematic of a ring coat method. It is the schematic of a ring coating (application | coating) head. 1 is a schematic configuration diagram of an example of an electrophotographic apparatus using a charging member of the present invention.

Explanation of symbols

1a conductive support member 1b conductive elastic layer 1c ground layer (seamless tube)
1d Surface layer 2a Conductive roller 2b Roller gripping shaft 2c Roller gripping shaft 2d Ring coating (application) head 2e Syringe pump 2f Paint storage tank 2g Motor 2h Pulley & belt 2i Ball screw 2j Slide guide 2k LM guide 2l Bracket 3a All Discharge port 3b opened in the periphery Liquid supply port 3c Liquid distribution chamber 21 Electrophotographic photosensitive member 22 Charging roller (charging member)
23 Exposure means 24 Development means 24a Toner carrier 24b Stirring member 24c Toner regulating member 25 Transfer roller 26 Cleaning means 27 Pre-exposure means P Transfer material L Laser light S1, S2 Bias supply power source

Claims (8)

  A charging member having at least a conductive support member, a conductive elastic layer formed on the conductive support member, a base layer formed on the conductive elastic layer, and a surface layer. The layer is a surface layer having a film thickness of 50 nm or more and 2 μm or less formed of a coating liquid containing at least one polymer selected from an acrylic fluorine-based polymer and an acrylic silicone polymer, and at least a polyol and a polyisocyanate. A charging member.   The charging member according to claim 1, wherein the underlayer is a seamless tube formed by an extruder.   The charging member according to claim 1, wherein the surface layer is a surface layer mainly composed of an acrylic urethane resin obtained by crosslinking an acrylic polyol with an isocyanate.   4. An electrophotographic apparatus according to claim 1, wherein the charging means is the charging member according to any one of claims 1 to 3.   A charging member having at least a conductive support member, a conductive elastic layer formed on the conductive support member, a base layer formed on the conductive elastic layer, and a surface layer. Charging characterized in that the layer is a surface layer formed of a coating liquid containing at least one polymer selected from an acrylic fluorine-based polymer and an acrylic silicone-based polymer, a polyol, a polyisocyanate, and a conductive agent. Element.   The charging member according to claim 5, wherein the underlayer is a seamless tube formed by an extruder.   The charging member according to claim 5 or 6, wherein the surface layer is a surface layer mainly composed of an acrylic urethane resin obtained by crosslinking an acrylic polyol with an isocyanate.   8. An electrophotographic apparatus according to claim 5, wherein the charging means is the charging member according to any one of claims 5 to 7.

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