JP4262000B2 - Conductive roller, conductive roller manufacturing method, and electrophotographic apparatus - Google Patents

Description

【０１１７】
【発明の効果】
以上のように本発明においては、少なくとも隣り合った二つの導電層を備え、その両方に絶縁性粒子を分散することによって、帯電が均一で安定しているローラと、それを安定して製造する事ができる。
【０１１８】
さらに、耐久後も安定して帯電が可能なため、製品としての安定性・高画質化も実現した。
【図面の簡単な説明】
【図１】 接触帯電・転写部材を用いた電子写真装置の構成を模式的に示したものである。
【図２】 本発明の実施例１に用いた金型・蓋体の一例を模式的に表したものであり、芯金、原料組成物を仕込んだ状態での断面図を模式的に表したものである。
【図３】 本発明を実施するための熱盤の一例を模式的に表したものである。
【図４】 本発明を実施するための押出し機の一例を模式的に表したものである。
【図５】 本発明を実施するための二層押し出し機の一例を模式的に表したものである。
【図６】 本発明における抵抗測定を実施するための測定装置を模式的に示したものである。
【図７】 本発明における三層の導電性ローラの拡大図を模式的に示したものである。
【図８】 本発明における二層の導電性ローラを模式的に示したものである。
【図９】 本発明における二層の導電性ローラの拡大図を模式的に示したものである。
【図１０】 本発明におけるの導電性ローラの拡大図を模式的に示したものである。
【符号の説明】
１ 像担持体
２ 帯電ローラ
３ 露光手段
４ 現像部材
５ 転写ローラ
６ 転写材
７ 定着部材
８ クリーニング部材
９ トナー
１０ 金型本体
１１ 蓋体（芯金保持部材）
１２ ガス抜き孔
１３ 未加硫原料組成物
１４ 芯金
１５ 金型を挿入する空孔部
１６ 熱盤（上下に分割可能）
１７ クロスヘッド
１８ 押出し機
１９ 芯金
２０ 未加硫組成物
２１ 材料供給孔
２２ 押し出し機（発泡層用）
２３ 押し出し機（非発泡層用）
２４ 二層用クロスヘッド
２５ 導電性ローラ
２６ 芯金
２７ アルミドラム
２８ 電源
２９ 芯金
３０ 非発泡層
３１ 発泡層
３２ セル
３３ 絶縁性粒子
３４ 絶縁性粒子
３５ 被覆層
３６ 非発泡層
３７ 発泡層[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a charging / transfer roller used in an image forming apparatus utilizing an electrophotographic process, a developing roller, a conductive roller used for an intermediate transfer member, and the like, and a manufacturing method thereofAnd electrophotographic equipmentIt is about.
[0002]
[Prior art]
  Conventionally, in an electrophotographic process such as a copying machine or a printer, first, the surface of the photoconductor is uniformly charged, and an image is projected onto the photoconductor from the optical system so that the charged portion is erased. A latent image is formed by the following method, and then printing is performed by forming a toner image by attaching toner and transferring the toner image to a recording medium such as paper.
[0003]
  In this case, the corona discharge method has generally been adopted for the operation of charging the first photoreceptor. However, since this corona discharge method requires application of a high voltage of 6 to 10 kV, it is not preferable from the viewpoint of safety maintenance of the machine. There is also an environmental problem because harmful substances such as ozone are generated during corona discharge.
[0004]
  For this reason, efforts have been made to charge systems that can be charged with a lower applied voltage than corona discharge and that can suppress the generation of harmful substances such as ozone. As an attempt of such a charging method, a method based on a contact method in which a charging member to which a voltage is applied is brought into contact with a member to be charged such as a photosensitive member with a predetermined pressure to charge the member to be charged has been proposed.
[0005]
  FIG. 1 is a schematic sectional view of an electrophotographic apparatus using a contact charging / transfer member. Reference numeral 1 denotes an image carrier as a member to be charged, which is a photoreceptor used in a drum type electrophotographic process comprising a conductive base layer using aluminum and a photoconductive layer formed on the outer peripheral surface thereof. Reference numeral 2 denotes a charging member that comes into contact with the photosensitive member and uniformly charges the surface of the photosensitive member to a predetermined potential. This example shows a roller shape (hereinafter referred to as a charging roller).
[0006]
  This charging roller has a central core and a conductive elastic layer formed on the outer periphery thereof. The charging roller is pressed against the photosensitive member 1 with a predetermined pressing force by a pressing means (not shown) such as a spring, and is rotated following the rotation of the photosensitive member 1. Further, the photoconductor 1 is contact-charged to a predetermined potential by applying a DC + AC (or only DC) bias to the core part. That is, in order to obtain a good image, a uniform contact state and conductivity are required. The surface of the photoreceptor 1 charged to a predetermined potential by the charging member 2 is exposed to image information by an exposure means 3 such as a laser or LED, whereby an electrostatic latent image corresponding to the target image information is formed. The
[0007]
  Next, the latent image is visualized as a toner image by the developing means 4. The toner image is charged from the back of the transfer material 5 with the reverse polarity of the toner by the transfer member 6, whereby the toner image on the surface of the photoreceptor 1 is transferred to the surface side of the transfer material 5. The transfer material 5 that has received the transfer of the toner image is separated from the photoreceptor 1 and fixed by heat and pressure by the fixing member 7. Further, the surface of the photoreceptor 1 after the image transfer is cleaned by the cleaning means 8 after removal of deposits such as residual toner at the time of transfer, and is repeatedly used for image formation.
[0008]
  However, the charging uniformity is slightly disadvantageous compared to the corona charging method.
[0009]
  In order to improve this charging uniformity, an AC voltage component (AC voltage component) having a peak-to-peak voltage more than twice the charging start voltage (Vth) is superimposed on the DC voltage corresponding to the desired surface potential Vd to be charged. An “AC charging method” is used in which applied voltage (pulsating voltage: voltage whose voltage value periodically changes with time) is applied to the contact charging member. This is for the purpose of smoothing the potential due to the AC voltage. The potential of the charged object converges to the potential Vd which is the center of the peak of the AC voltage, and is not affected by external disturbances such as the environment. This is an excellent charging method.
[0010]
  However, in order to superimpose a high-voltage AC voltage that is a peak-to-peak voltage more than twice the discharge start voltage (Vth) when a DC voltage is applied, an AC power supply is required in addition to the DC power supply, which increases the cost of the device itself. It becomes a factor. Furthermore, there is a problem that the durability of the charging member and the photosensitive member is liable to be reduced by consuming a large amount of alternating current.
[0011]
  Although these problems can be solved by charging by applying only a DC voltage to the charging member, there are the following problems when only the DC voltage is applied to the charging member.
[0012]
  When only a DC voltage is applied to the conventional charging member, uneven charging occurs when the surface of a charged body such as a photosensitive member is charged to a desired charging potential or higher or when the potential is insufficient. In particular, in an electrophotographic process without pre-exposure, which is a process for erasing the potential on the photoreceptor before primary charging, it is likely to occur in the potential portion of the halftone image area.
[0013]
  When a halftone image is output by, for example, an electrophotographic apparatus using a reversal development method using a conventional charging roller in which such a problem occurs, the above-mentioned charging unevenness is partially white streaks or white spots on the image. Or, it appears as a halftone image surface with black streaks, black spots, or roughness, and there is a problem in that the image quality deteriorates. The occurrence of the uneven charging potential tends to be particularly noticeable in a low temperature and low humidity environment.
As means for suppressing this uneven charging, uniform resistance distribution and improved surface properties have been studied.
[0014]
  Among these, regarding the surface property, Patent Document 1 proposes that the outermost layer has a surface roughness of 5 μm or less to apply only a DC voltage to uniformly charge the object to be charged. However, as a result of the additional test, since the surface roughness was low, a lot of black streaks were generated at the edge of the image, and black streaks were also partially generated at the center of the image.
[0015]
  As a means for controlling the surface roughness, in Patent Document 2, elastic particles having a particle size of 7 to 30 μm are dispersed in a matrix resin that is the outermost layer of the charging member to form a surface roughness Rz of 7 to 30 μm. It has been proposed. However, as a result of additional tests, when a single particle having a small particle size in the above range is used, it is necessary to add a large amount in order to achieve the target surface roughness. For this reason, the viscosity of the paint is increased, and it becomes difficult to control the appropriate film thickness. In addition, the rigidity of the film itself was increased when the surface layer was cured, and this was a cause of generation of surface wrinkles due to a large difference in shrinkage between the elastic layer and the elastic layer during cooling. Even in the above range, when a single particle having a large particle size is used and dispersed, a particle having a large particle size in the particle size distribution tends to be relatively agglomerated, and the portion becomes insufficient in charging potential. It became.
[0016]
  As a manufacturing method of a roller used for such charging, transfer, developing member, etc., after vulcanizing a product obtained by extruding a kneaded raw material composition in a tube shape by blending a polymer raw material, a foaming agent and various additives, Pressed into a metal core that has been pre-applied with an adhesive and polished with a cylindrical grinder etc. to adjust the outer diameter, or a metal core pre-applied with an adhesive is extruded with a raw material composition using a crosshead and added. A method of adjusting the outer diameter by polishing after sulfuration is known.
[0017]
  Or after extruding the said raw material composition cylindrically around the metal core previously apply | coated with the adhesive agent, it arrange | positions inside a metal mold | die and performs vulcanization | cure by heating a metal mold | die, A roller can be obtained by forming an elastic body in the shape of a cylinder around the periphery.
[0018]
  Furthermore, a conductive layer is formed around a cylindrical elastic body for adjusting resistance or adjusting surface properties. As a method for producing this conductive layer, there is used a method in which a paint containing each component is prepared and this paint is applied by dipping or spraying to form a coating film. Insulating particles for controlling the roughness are dispersed in the paint.
[0019]
  However, when a conductive layer is formed by dipping or the like using a coating liquid in which a large size of insulating particles are dispersed, large particles may settle with time, which is not preferable in terms of production stability. It was difficult to achieve a desired roughness stably.
[0020]
[Patent Document 1]
  JP-A-5-341620
[Patent Document 2]
  SpecialForgivenessNo. 3024248
[0021]
[Problems to be solved by the invention]
  An object of the present invention is to provide a surface shape with good charging uniformity and a method for stably producing the same while solving the above-described problems.
[0022]
[Means for Solving the Problems]
  As a result of intensive investigations for improving the above problems, the present inventors have reached the present invention.
  IeThe present invention is next toTwo guidesElectric layerWith insulating particles dispersed in bothLeadElectric rollerOf the two adjacent conductive layers, the insulating particles dispersed in the outer conductive layer have an average particle size of 1 μm or more and less than 10 μm, and the insulating properties dispersed in the inner conductive layer Conductive roller having an average particle diameter of 10 μm or more and 50 μm or lessIt is.
[0023]
  Also,The present inventionCylindrical molding die having lids at both ends for holding the cored bar on the concentric shaft with the inner peripheral surface of the molding dieWithin,
(A) a cored bar,
(B)Foam polymer raw material,Blowing agent,Insulating particlesas well asAdditiveButFormulationIsExtruding the kneaded unvulcanized unfoamed raw material compositionFormed by,The inner diameter isLarger than the outer diameter of the cored barThe outer diameter isCylindricalMolding goldSubstantially cylindrical shape smaller than the inner diameter of the moldWith things
ThebothArrangementPlace,Vulcanize and foamthingAccordingHave a foam layerForming a roller;
The roller using a coating liquid in which insulating particles are dispersedOuter peripheral surfaceForming a coating layer on topWhen
TheHaveLeadElectric roller manufacturing methodIs.
  Further, the present invention provides a cylindrical molding die having lids at both ends for holding the cored bar on a concentric axis with the inner peripheral surface of the molding die.
(A) a cored bar,
(B) Unvulcanized unfoamed raw material composition in which a foam polymer material, a foaming agent and an additive are blended and kneaded, and an unvulcanized non-vulcanized material in which a polymer raw material, insulating particles and an additive are blended and kneaded The unvulcanized non-foamed raw material formed by extruding the foaming raw material composition integrally and simultaneously, the inner diameter being larger than the outer diameter of the core metal and the outer diameter being smaller than the inner diameter of the cylindrical molding die A substantially cylindrical laminate in which the composition is outside the unvulcanized unfoamed raw material composition;
Forming a roller having a foamed layer and a non-foamed layer on the foamed layer by performing vulcanization and foaming together,
Forming a coating layer on the outer peripheral surface of the roller using a coating liquid in which insulating particles are dispersed;
Is a method of manufacturing a conductive roller having
  Further, the present invention provides a cylindrical molding die having lids at both ends for holding the cored bar on a concentric axis with the inner peripheral surface of the molding die.
(A) a cored bar,
(B) formed by extruding an unvulcanized unfoamed raw material composition in which a foam polymer raw material, a foaming agent and an additive are blended and kneaded, and the outer diameter is larger than the outer diameter of the cored bar. On the outer peripheral surface of a substantially cylindrical one that is smaller than the inner diameter of the cylindrical molding die, insulating particles are applied;
And forming a roller having a foam layer by performing vulcanization and foaming, and
Forming a coating layer on the outer peripheral surface of the roller using a coating liquid in which insulating particles are dispersed;
Is a method of manufacturing a conductive roller having
  The present invention also provides an electrophotographic apparatus having a photoconductor and a charging roller disposed in contact with the surface of the photoconductor for charging the surface of the photoconductor, wherein the charging roller is the conductive roller. An electrophotographic apparatus characterized by the above.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
  The first invention related to this application is,next toTwo guidesElectric layerWith insulating particles dispersed in bothLeadElectric roller.
[0025]
  FIG. 7 schematically shows a side view and a sectional view of the roller of the present invention.
[0026]
  FIG. 8 schematically shows an enlarged sectional view of the roller of the present invention.
[0027]
  Reference numeral 29 denotes a cored bar, which has a foam layer 31 on its outer peripheral surface and a non-foamed layer 30 on its outer peripheral surface. In the foam layer 31, the foam cells are 32, and 33 are insulating particles. The non-foamed layer 30 also includes insulating particles 34.
[0028]
  By providing a layer in which two adjacent insulating particles are dispersed, a conductive roller having a desired surface shape can be obtained by independently controlling the widths of the two types of waviness.
[0029]
  The insulating particles in the present invention are 10¹²It has a resistance value of Ω · cm or more.
[0030]
  Powder resistance is 100kg / cm for powder.²It measured about what was press-molded.
[0031]
  Furthermore, there may be other layers above and below the two adjacent conductive layers, and there may be a thin layer on the outer periphery as a protective layer when the elastic layer has a lower layer.
[0032]
  No. related to this application1InventionIn the conductive rollerIs,in frontOutsideConductivelayerDistributedThe average particle size of the insulating particles is 1 μm or more and less than 10 μm,AboveinsideConductivelayerDistributedThe average particle size of the insulating particles is 10 μm or more and 50 μm or less.The
[0033]
  By dispersing large particles in the base layer, a relatively large undulation is formed in the base layer, and fine undulation is provided on the base layer, whereby a roller with uniform and stable charging can be obtained.
[0034]
  Also,If the surface is too rough, image defects due to adhesion of toner, paper dust, and the like due to durability and image defects due to uneven contact occur, which is not preferable. To that end, the outsideConductiveThe average particle size of the insulating particles of the layer is 1 μm or more and less than 10 μm,ConductiveThe average particle diameter of the insulating particles in the layer is preferably 10 μm or more and 50 μm or less.
[0035]
  No. related to this application2The present invention relates to this application.WowFirst1'sinventionIn the conductive rollerA charging roller that is placed in contact with the surface of the photoreceptor to charge the surface of the photoreceptor.LeadElectric roller.
[0036]
  If a stable roller having a uniform charging property is used as a charging roller, the product can be used stably over a longer period than before.
[0037]
  No. related to this application3The invention provides a cylindrical molding die having lids at both ends for holding the cored bar on the concentric shaft with the inner peripheral surface of the molding die.Within,
(A) a cored bar,
(B)Foam polymer raw material,Blowing agent,Insulating particlesas well asAdditiveButFormulationIsExtruding the kneaded unvulcanized unfoamed raw material compositionFormed by,The inner diameter isLarger than the outer diameter of the cored barThe outer diameter isCylindricalMolding goldSubstantially cylindrical shape smaller than the inner diameter of the moldWith things
TheBothArrangedPlace,Vulcanize and foamthingAccordingHave a foam layerForming a roller;
Using a coating liquid in which insulating particles are dispersedOn the outer peripheral surface of the rollerStep of forming a coating layerWhen
TheHaveIt is a manufacturing method of a conductive roller.
[0038]
  Examples of a method for forming a lower layer having a desired surface in which particles are dispersed include polishing and in-mold molding. However, when a non-foamed cylindrical roller mixed with insulating particles is polished to adjust the outer diameter, there is a possibility that the particles may fall off during polishing. Moreover, when it is not foam molding, there are cases where the particles are completely buried and undulations cannot be formed on the surface. Therefore, more preferably, molding is performed by foaming in a mold.
[0039]
  Thus, it has been found that a desired surface can be formed by using foam molding in a mold and adjusting the amount of the raw material composition charged in the mold and mold so as to obtain an appropriate internal pressure and expansion ratio.
[0040]
  In FIG. 4, the outline | summary of the extruder used in order to shape | mold the said cylindrical unvulcanized raw material composition was shown typically. Reference numeral 18 denotes an extruder main body, an unvulcanized composition is introduced from a material supply hole 21, a core metal 19 is inserted from the back of the crosshead 17, and a cylindrical unvulcanized composition around the core metal Are formed and extruded.
[0041]
  Moreover, an example of a metal mold | die and a cover body is typically shown in FIG. A lid 11 capable of holding the cored bar 14 on the concentric shaft is provided at both ends of the mold body 10 so that the cylindrical unvulcanized composition is molded around the cored bar. The lid 11 for holding the metal core also plays a role of regulating the axial flow of the material, and further includes a hole 12 for extracting the foaming gas from the cavity.
[0042]
  Note that only a cylindrical unvulcanized raw material composition may be formed by extrusion and charged into a mold together with a core metal.
[0043]
  In order to uniformly form small waviness on the outer peripheral surface of a roller with a surface having large waviness with insulating particles, a liquid coating liquid in which insulating particles are dispersed is used to form the shape of the lower layer surface. Thus, a desired surface shape can be realized by forming the coating layer.
[0044]
  The method for forming the coating layer is not particularly limited, but a method of forming a coating film by preparing a paint containing each component and applying the paint by a dipping method or a spray method is preferably used. In this case, when the outer layer has a plurality of layers, dipping and spraying may be repeated using the paint forming each layer.
[0045]
  No. related to this application4The invention provides a cylindrical molding die having lids at both ends for holding the cored bar on the concentric shaft with the inner peripheral surface of the molding die.Within,
(A) a cored bar,
(B)Foam polymer raw material,Blowing agentas well asAdditiveButFormulationIsKneaded unvulcanized unfoamed raw material composition, And, Polymer raw material,Insulating particlesas well asAdditiveButFormulationIsKneaded unvulcanized unfoamed raw material composition,oneIs it physicalSameSometimes extrudingFormed by,The inner diameter isLarger than the outer diameter of the cored barThe outer diameter isCylindricalMolding goldSmaller than the inner diameter of the moldThe unvulcanized unfoamed raw material composition is outside the unvulcanized unfoamed raw material compositionSubstantially cylindrical laminateWhen
TheBothArrangedPlace,Vulcanize and foamthingAccordingHaving a foam layer and a non-foam layer on the foam layerForming a roller;
Using a coating liquid in which insulating particles are dispersedOn the outer peripheral surface of the rollerStep of forming a coating layerWhen
TheHaveIt is a manufacturing method of a conductive roller.
[0046]
  FIG. 9 schematically shows an enlarged sectional view of the roller of the present invention. In FIG. 9, 37 is a foamed layer and 36 is a non-foamed layer, which are molded integrally at the same time. Further, a coating layer 35 is provided on the outside thereof.
[0047]
  In FIG. 5, the outline | summary of the extruder used in order to shape | mold the said cylindrical laminated body was shown typically.
[0048]
  The unvulcanized unfoamed raw material composition and the unvulcanized non-foamed raw material composition are respectively fed using separate extruders 22 and 23, and the inner unvulcanized unfoamed inner foam is fed at the extrusion head 24. The raw material composition and the outer unvulcanized unfoamed raw material composition are combined, and the outer unvulcanized unfoamed layer is coated on the outer periphery of the inner unvulcanized unfoamed layer, and is cylindrical. Is formed.
[0049]
  When the inner layer is formed of a foam, the roller hardness increases depending on the amount of insulating particles mixed, which may not be preferable. In that case, a desired surface having a low hardness can be obtained by forming a non-foamed layer having a thickness of 100 μm to 2 mm mixed with insulating particles at the same time as forming a foamed layer in the lower layer. A roller can be formed.
[0050]
  No. related to this application5The invention provides a cylindrical molding die having lids at both ends for holding the cored bar on the concentric shaft with the inner peripheral surface of the molding die.Within,
(A) a cored bar,
(B)Foam polymer raw material,Blowing agentas well asAdditiveButFormulationIsExtruding the kneaded unvulcanized unfoamed raw material compositionFormed by,The inner diameter isLarger than the outer diameter of the cored barOuter diameter isCylindricalMolding goldSubstantially cylindrical shape smaller than the inner diameter of the moldInsulating particles are coated on the outer peripheral surface of
TheBothArrangedPlace,Vulcanize and foamthingAccordingHave a foam layerForming a roller;
Using a coating liquid in which insulating particles are dispersedOn the outer peripheral surface of the rollerStep of forming a coating layerWhen
TheHaveManufacturing method of conductive rollerIs.
[0051]
  FIG. 10 schematically shows an enlarged sectional view of the roller of the present invention.
[0052]
  When it is desired to control the roughness more or when it is not desired to increase the hardness by adding a large amount of insulating particles, it is preferable that the particles are concentrated in the vicinity of the interface between two adjacent layers having conductivity.
[0053]
  It consists of an unvulcanized cylindrical raw material composition coated with insulating particles while rotating them, vulcanized in a mold, and then formed a coating layer using a coating liquid in which the insulating particles are dispersed. By doing so, it is possible to obtain a roller in which insulating particles are concentrated on the interface and its outer periphery.
[0054]
  Therefore, there are no insulating particles inside the interface between the two layers, and low hardness can be realized.
[0055]
  It is more preferable to use a roller having low hardness because the photoreceptor is not damaged with use, and the pressure contact state is stabilized, so that a uniform and stable image can be obtained.
[0056]
  In addition, the method of applying insulating particles to the surface of the unvulcanized composition includes, in addition to the method of applying powder, a method of applying the particles by dispersing in a solvent or water and using dipping or spraying. It may be used.
[0057]
  As described above, in the present invention,,next toTwo guidesElectric layerWith insulating particles dispersed in boththingCan stably obtain a roller with good charging uniformity.thingCan do.
[0058]
  The heating of the unvulcanized composition may be any method such as a hot stove, vulcanized can, hot platen, far / near infrared, induction heating, etc., and the heating temperature is 130 to 250 ° C. for 5 to 120 minutes, preferably It is performed at 140 to 220 degrees in 10 to 40 minutes. Thereafter, secondary vulcanization may be performed as necessary.
[0059]
  Conductive lowLa'sThe polymers include natural rubber, butadiene rubber, styrene butadiene rubber (SBR), nitrile rubber, ethylene propylene rubber (EPDM), chloroprene rubber (CR), nitrile butadiene rubber (NBR), epichlorohydrin rubber, butyl rubber, silicone rubber, urethane rubber. Any of fluorine rubber and chlorine rubber may be used.
[0060]
  Examples of the conductive powder dispersed in the polymer include carbons such as carbon black and conductive carbon, graphite, and TiO. ₂ ・ SnO ₂ ・ Gold oxide such as ZnO, SnO ₂ And Sb ₂ O ₃ Individual solutions of ZnO and Al ₂ O ₃ And a metal oxide such as Cu · Ag, and 5 to 200 parts by weight is added to 100 parts by weight of the polymer raw material.
[0061]
  As foaming foaming agents, organic foaming agents include ADCA (azodicarbonamide), DPT (dinitrosopentamethylenetetraamine), TSH (P.toluenesulfonylhydrazide), OBSH (oxybisbenzenesulfenyl hydrazide), etc. May be used. The addition amount is 2 to 30 parts by weight with respect to 100 parts by weight of the polymer raw material. Examples of the inorganic foaming agent include sodium bicarbonate and ammonium carbonate. Further, the foaming agent, foaming aid and the like may be added as appropriate.
[0062]
  Examples of the vulcanizing agent include sulfur, metal oxide, and organic oxide. Examples of the inorganic filler include carbon black, talc, and clay. Other known vulcanization accelerators and process oils are appropriately added.
[0063]
  Specific examples of the material for the covering layer include polyester resin, acrylic resin, urethane resin, acrylic urethane resin, nylon resin, epoxy resin, polyvinyl acetal resin, vinylidene chloride resin, fluorine resin, and silicone resin. Any of aqueous systems can be used.
[0064]
  Furthermore, an appropriate amount of an additive such as a crosslinking agent can be added to the conductive resin layer as necessary. In this case, any crosslinking agent may be used as long as a desired crosslinking effect can be obtained. For example, epoxy-based, oxazoline-based, melamine-based, isocyanate-based, and phenol-based crosslinking agents can be exemplified.
[0065]
  In addition, a conductive agent can be added or adjusted to the coating layer by adding a conductive agent. In this case, the conductive agent is not particularly limited, but conductive properties such as ketjen black EC and acetylene black. Carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT, carbon for color (ink) subjected to oxidation treatment, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide Metals such as titanium oxide, zinc oxide, nickel, copper, silver, germanium, metal oxides, and the like can be used.
[0066]
  Further, when the conductive agent is used in an organic solvent, it is preferable to perform surface treatment such as silane coupling treatment on the surface of the conductive agent in consideration of dispersibility.
[0067]
  Insulating particles include calcium carbonate, clay, talc, silica, methylsiloxane network polymer and resin, metal oxides such as zinc oxide, acrylic acid and its ester, methacrylic acid and its ester, vinyl alcohol, its ester and its Ether, styrene and α-methylstyrene, SBR (styrene butadiene rubber), CR (chloroprene rubber), EPDM (ethylene propylene dienter rubber), IIR (butyl rubber), NBR (nitrile butadiene rubber), silicone rubber, urethane rubber, epichlorohydrin rubber, etc. Rubber, RB (butadiene resin), polystyrene resin such as SBS (styrene butadiene styrene elastomer), polyolefin resin, polyester resin, polyurethane, PVC (polyvinyl chloride), acrylic Le resins, styrene-vinyl acetate copolymer, among those made of butadiene-acrylonitrile copolymer, resistance 10 ¹² Any grade may be used as long as it is Ω · cm or higher.
[0068]
  The insulating particles may be subjected to a hydrophobic surface treatment so as to be easily dispersed in the paint. The amount of the particles added is in the range of 10 to 50 parts by weight with respect to 100 parts by weight of the resin.
[0069]
  The thickness of this coating layer is preferably 5 to 50 μm. In particular, the thickness is preferably 10 to 30 μm. If the thickness of the outer layer 13 exceeds 50 μm, the outer layer 13 may become hard and the flexibility may be impaired. If the thickness is 10 μm or less, the coating may not be stable.
[0070]
【Example】
  Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, “part” means “part by mass”.
[0071]
  Example 1
  The foamed conductive roller used in this example was manufactured by the following method.
[0072]
  As an unvulcanized raw material composition, 120 parts of ethylene-propylene-diene terpolymer (EPT9070E made by Mitsui Petrochemical Co., Ltd.) and Ketjen Black (Ketjen Black EC manufactured by Mitsubishi Chemical Corporation) as a conductive agent are used. ), 50 parts of SRF carbon black (Asahi # 35 Asahi Carbon Co., Ltd.), 50 parts of paraffin oil as a softener, 5 parts of zinc oxide as a vulcanization accelerator, 1 part of stearic acid, 2 parts of sulfur as a crosslinking agent , 2 parts of mercaptobenzothiazole (M) as vulcanization accelerator, 1 part of zinc dibutyldithiocarbamate (ZnBDC), 1 part of tetramethylthiuram disulfide (TMTD), 4 parts of ADCA and 8 parts of OBSH as foaming agent, average particle as insulating particles 20 parts of urethane particles (Art Pearl, Negami Kogyo) with a diameter of 30μm are kneaded and open roll It was mixed using.
[0073]
  In order to form the obtained raw material composition around the cored bar, a die having an inner diameter of 9.6 mm was set in an extruder schematically shown in FIG. 4, and the temperature of the head was adjusted to 50 degrees in advance. Next, a core metal having a diameter of 6 mm was prepared and extruded at the same time as the rubber to form an unfoamed roller. Then, the edge part cutting process of the excess unvulcanized composition part was performed so that the length of a raw material composition might become substantially the same length with respect to 232 mm of the length of the void | hole part in a metal mold | die.
[0074]
  Next, as schematically shown in FIG. 2, the obtained non-foamed roller was inserted into a mold cylinder and fixed with lids provided at both ends of the mold. Next, it is inserted into a heating plate heated in advance at 160 ° C. and heated for 15 minutes to vulcanize and foam, and the length of the rubber part is 232 mm and the diameter of the rubber part is φ12 on the core metal having a diameter of φ6 mm. A conductive roller having a thickness of 0.0 mm was obtained.
[0075]
  In addition, the schematic diagram of the heating board used in the present Example is shown in FIG.
[0076]
  The cylindrical mold has a hole portion 15 having an inner diameter substantially the same as the maximum outer diameter of the cylindrical mold and approximately the same length as the mold, and the axis of the cylindrical mold. It is an apparatus that is divided in parallel with the direction, and performs vulcanization and foaming simultaneously by heating a mold in which a raw material composition is disposed together with a cored bar.
[0077]
  Next, in order to provide a coating layer on the outer peripheral surface of the conductive roller, 137 parts by weight of a lactone-modified acrylic polyol (trade name “Placcel DC2009 (hydroxyl value 90 KOHmg / g)” manufactured by Daicel Chemical Industries, Ltd.) It was dissolved in 463 parts by weight of MIBK (methyl isobutyl ketone) to obtain a solution having a solid content of 15.94% by weight. With respect to 200 parts by weight of this acrylic polyol solution, 54.3 parts by weight of conductive tin oxide powder (trade name “SN-100P” manufactured by Ishihara Sangyo Co., Ltd.), silicone oil (trade name “SH-28PA”) : 0.01% by weight of Toray Dow Corning Silicone Co., Ltd.) and 1.46 parts by weight of acrylic particles (Chemisnow, Soken Science MX-180) having an average particle size of 1.6 μm as insulating particles. Glass beads were added to and dispersed using a paint shaker. 25.4 parts by weight of block type isocyanurate type trimer (IPDI) (trade name “Vestanat B1370” manufactured by Degussa Huls) of isophorone diisocyanate in 330 parts by weight of this dispersion and isocyanurate type of hexamethylene diisocyanate 16.2 parts by weight of a trimer (HDI) (trade name “Duranate TPA-B80E” manufactured by Asahi Kasei Kogyo Co., Ltd.) was mixed with stirring in a ball mill to obtain a paint.
[0078]
  The paint was applied to the surface of the conductive roller by dipping. After dipping, it was air-dried for 30 minutes and then dried in an oven at 160 ° C. for 1 hour. At this time, the film thickness was 15 μm. The electric resistance of the two-layer conductive roller is about 1.0 × 10⁶Ω. The hardness of the roller was 51 with Asker C (500 g load).
[0079]
  As shown schematically in FIG. 6, the roller resistance of the conductive roller is such that the roller 25 is brought into contact with the columnar aluminum drum 27 and rotated with a DC voltage of 100 V from the power supply 28 between the drum and the drum. The voltage was applied by applying a voltage and the voltage applied to the resistance was measured.
[0080]
  Using the conductive roller obtained as described above as a charging roller, the following image evaluation was performed.
[0081]
  The electrophotographic laser printer used in this test is an A4 vertical output machine, the output speed of the recording medium is 94 mm / sec, and the image resolution is 1200 dpi. The photoreceptor is a reversal development type photosensitive drum in which an aluminum cylinder is coated with an OPC layer having a film thickness of 18 μm, and the outermost layer is a charge transport layer using a modified polycarbonate as a binder resin. The toner was obtained by polymerizing a random copolymer of styrene and butyl acrylate containing a charge control agent, a pigment and the like centering on wax, and further polymerizing a thin polyester layer on the surface to externally add silica fine particles. This toner is a polymerized toner having a glass transition temperature of 63 ° C. and a volume average particle diameter of 6 μm.
[0082]
  All image evaluations were performed in a low-temperature and low-humidity environment (L / L: 15 ° C. × 10% Rh), and a halftone image (an image in which a horizontal line with a width of 1 dot and an interval of 2 dots was drawn in the direction perpendicular to the rotation direction of the photoreceptor) Was output, and 15000 sheets were subjected to continuous durability before endurance, and it was checked whether charging unevenness before and after endurance occurred. A sample in which charging unevenness did not occur was marked with ◎, a sample with slight occurrence was marked with ○, a sample with moderate occurrence was marked with Δ, and a sample with very large unevenness was marked with ×.
[0083]
  The results of image evaluation are shown in Table 1. The charging roller of this example was stable without image unevenness before and after durability as seen in the comparative example.
[0084]
  (Example 2)
  The foamed conductive roller used in this example was manufactured by the following method.
[0085]
  As an unvulcanized unfoamed raw material composition, 120 parts of an ethylene-propylene-diene terpolymer (EPT 7070E manufactured by Mitsui Petrochemical Co., Ltd.) is used as a conductive agent, and SRF carbon black (Asahi # 35 Asahi 60 parts of carbon), 50 parts of paraffin oil as a softening agent, 5 parts of zinc oxide as a vulcanization accelerator, 1 part of stearic acid, 2 parts of sulfur as a crosslinking agent, mercaptobenzothiazole (as a vulcanization accelerator) M) 2 parts, zinc dibutyldithiocarbamate (ZnBDC) 1 part, tetramethylthiuram disulfide (TMTD) 1 part, ADCA 4 parts and OBSH 8 parts as a foaming agent, urethane particles having an average particle diameter of 30 μm as insulating particles (Art Pearl, Negami (Industry) 20 parts were mixed using a kneader and an open roll.
[0086]
  As an unvulcanized unfoamed raw material composition, 100 parts of epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (CG102 manufactured by Daiso Corporation) is used as an ionic conductive agent, 1 part of tetrabutylammonium perchlorate, carbon 60 rolls of cal (silver W), 1 part of stearic acid as processing aid, 20 parts of adipic acid ester (W305ELS) as plasticizer, 0.5 part of sulfur as vulcanizing agent, 1.5 parts of TRA as crosslinking aid And mixed.
[0087]
  The obtained unvulcanized non-foamed raw material composition and unvulcanized unfoamed raw material composition had an inner diameter of φ10.0 mm on an extruder schematically shown in FIG. 5 and a crosshead capable of simultaneously extruding a cored bar. By setting a certain die and extruding it at the same time, a cylindrical laminated body integrated with the core metal is formed, and the rubber has a length substantially the same as the length of the hole part 224 mm in the mold. The part was cut and the cylindrical laminated body was created around the metal core. In addition, the thickness of a non-foamed layer and a foamed layer is performed by controlling the ratio of the rotation speed of each extruder. In this example, adjustment was performed so that the thickness of the non-foamed layer was about 500 μm.
[0088]
  Thereafter, using the above-mentioned cylindrical laminate, it was charged into a mold in the same manner as in Example 1, heated, and further insulating particles were acrylic particles having an average particle size of 1.6 μm (Chemisnow, Soken Science MX-180). ) By applying the coating layer in the same manner as in Example 1 except for changing to 1.46 parts, about 1.0 × 10⁶  An Ω double-layer roller was obtained. The roller hardness was 47 as measured in the same manner as in Example 1.
[0089]
  The results of image evaluation are shown in Table 1. There was no occurrence of image unevenness before and after durability as seen in the comparative example, and the image was stable.
[0090]
  (Example 3)
  In this example, 20 parts of urethane particles (Art Pearl, Negami Kogyo) having an average particle diameter of 30 μm were used as the insulating particles in the inner layer, and the insulating particles in the outer layer were made of silicone particles (Tospearl, A conductive roller was prepared in the same procedure as in Example 2 except that 1.46 parts of Toshiba Silicone was used.
[0091]
  The results of image evaluation are shown in Table 1. There was no occurrence of image unevenness before and after durability as seen in the comparative example, and the image was stable.
[0092]
  (Reference example 1)
  BookReference exampleThen, 20 parts of urethane particles (Art Pearl, Negami Industries) having an average particle size of 30 μm were used as the insulating particles in the inner layer, and acrylic particles (Chemisnow, MX-2000) having an average particle size of 19 μm were used as the insulating particles in the outer layer. ) A conductive roller was prepared in the same procedure as in Example 2 except that 1.46 parts were used.
[0093]
  The results of image evaluation are shown in Table 1. Although there was no defect as seen in Comparative Example 1, there was some unevenness even in the initial state, and after the endurance, the amount of image unevenness slightly increased and was Δ level.
[0094]
  (Reference example 2)
  BookReference exampleThen, 20 parts of silicone particles (Tospearl, Toshiba Silicone) with an average particle size of 5 μm are used as the insulating particles in the inner layer, and acrylic particles (Chemisnow, Soken Kagaku) with an average particle size of 1.6 μm as the insulating particles in the outer layer. MX-180) A conductive roller was prepared in the same manner as in Example 2 except that 1.46 parts were used.
[0095]
  The results of image evaluation are shown in Table 1. Although there was no occurrence of image unevenness before and after endurance as seen in Comparative Example 1, slight unevenness could be confirmed before and after endurance, and the level was good.
[0096]
  (Reference example 3)
  BookReference exampleThen, 20 parts of urethane particles (Art Pearl, Negami Industrial Co., Ltd.) having an average particle diameter of 30 μm are used as insulating particles in the inner layer, and 1.46 parts of silica having a primary particle diameter of 0.02 μm are used as insulating particles in the outer layer. A conductive roller was prepared in the same procedure as in Example 2 except that it was used.
[0097]
  The results of image evaluation are shown in Table 1. Although there was no image unevenness as seen in Comparative Example 1, image unevenness before and after durability could be confirmed, and the level was Δ level.
[0098]
  (Reference example 4)
  BookReference exampleThen, 20 parts of sandy calcium carbonate (G60 Sankyo Flour Milling) with an average particle size of 90 μm is used as the insulating particles in the inner layer, and acrylic particles (Chemisnow, Soken) with an average particle size of 1.6 μm are used as the insulating particles in the outer layer. (Scientific MX-180) A conductive roller was prepared in the same procedure as in Example 2 except that 1.46 parts were used.
[0099]
  The results of image evaluation are shown in Table 1. Although there was no occurrence of image unevenness as seen in Comparative Example 1 in the initial state, the occurrence of image unevenness was confirmed after endurance, and the level was x.
[0100]
  (Example4)
  In this example, a single-layer unfoamed roller was prepared in the same manner as in Example 1 except that the insulating particles in the inner layer were removed. Next, while rotating the non-foamed roller, it rotates in the reverse direction of the non-foamed roller and is applied to the entire surface of the non-foamed roller by pressing against the brush to which the insulating particles are supplied. The inside was charged and vulcanized and foamed.
[0101]
  Insulating particles used were urethane particles having an average particle diameter of 30 μm (Art Pearl, Negami Industries).
[0102]
  Further, a procedure similar to that in Example 2 was used except that 1.46 parts of acrylic particles having an average particle size of 1.6 μm (Chemisnow, Soken Science MX-180) were used as insulating particles in order to provide an outer coating layer. Then, a coating layer was formed to produce a conductive roller.
[0103]
  The roller hardness was measured in the same manner as in Example 1 and was 42. A roller having a lower hardness than Examples 1 and 2 could be produced.
The results of image evaluation are shown in Table 1. There was no occurrence of image unevenness before and after durability as seen in the comparative example, and the image was stable.
[0104]
  (Comparative Example 1)
  In this comparative example, a conductive roller was prepared by the following method.
[0105]
  100 parts of epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (CG102 manufactured by Daiso Corporation), 1 part of tetrabutylammonium perchlorate as an ionic conductive agent, 60 parts of charcoal (silver W), as a processing aid 1 part of stearic acid, 20 parts of adipic acid ester (W305ELS) as a plasticizer, 0.5 part of sulfur as a vulcanizing agent and 1.5 parts of TRA as a crosslinking aid were mixed in an open roll.
[0106]
  This was extruded into a cylindrical shape having an outer diameter of 15 mm and an inner diameter of 5.5 mm with a rubber extruder, cut into a length of 240 mm, and then vulcanized with steam at 160 ° C. for 30 minutes in a vulcanizing can to obtain a vulcanized tube. . Next, a core metal having a diameter of 6 mm to which an adhesive was applied in advance was inserted into the vulcanized tube, and then the adhesive was cured in a hot air oven at 160 ° C. for 30 minutes to obtain an unpolished product. Both ends of this unpolished rubber part were cut off to make the length of the rubber part 232 mm and then polished with a rotating grindstone to obtain a single-layer conductive roller having a diameter of φ12.0 mm.
[0107]
  Further, a coating layer was formed on the outer peripheral surface in the same manner as in Example 1 except that the insulating particles were removed to obtain a two-layer conductive roller.
[0108]
  As a result of the image evaluation, as shown in Table 1, it was confirmed that x-level image unevenness occurred before and after endurance.
[0109]
  (Comparative Example 2)
  In this comparative example, the same procedure as in Comparative Example 1 was performed except that 16.06 parts of acrylic particles (Chemisnow, Soken Science MX-180) having an average particle size of 1.6 μm were used as the insulating particles in the outer layer. A sex roller was created.
[0110]
  As a result of the image evaluation, as shown in Table 1, occurrence of image unevenness was confirmed both before and after the endurance, and the level was Δ level.
[0111]
  (Comparative Example 3)
  In this comparative example, as the insulating particles in the outer layer, 1.46 parts of an average particle size of 1.6 μm acrylic particles (Chemisnow, Soken Science MX-180) and urethane particles having an average particle size of 30 μm (Art Pearl, Negami Kogyo) A conductive roller was prepared in the same procedure as in Comparative Example 1 except that both 14.6 parts were used.
[0112]
  As shown in Table 1, the results of the image evaluation were good and the level was good although the occurrence of image unevenness could be confirmed before and after durability.
[0113]
  However, when a large number of samples were prepared in the same manner, when the sample was prepared after 4 hours, the sample was confirmed to have a change in roughness that was probably due to sedimentation of urethane particles, and the level of image unevenness was also Δ.
[0114]
  (Comparative Example 4)
  This comparative example is the same as Comparative Example 1 except that 20 parts of urethane particles (Art Pearl, Negami Industries) having an average particle diameter of 30 μm are used as insulating particles in the inner layer, and the inner layer is formed. A conductive roller was prepared according to the procedure described in 1.
[0115]
  As a result of the image evaluation, as shown in Table 1, Δ level image unevenness was confirmed before endurance, and x level image unevenness was confirmed after endurance.
[0116]
[Table 1]

[0117]
【The invention's effect】
  As described above, in the present invention, at least two adjacent guides are used.Electric layer, And by dispersing the insulating particles in both of them, it is possible to stably produce a roller with uniform and stable charging.
[0118]
  In addition, since it can be charged stably after durability, it has achieved stability and high image quality as a product.
[Brief description of the drawings]
FIG. 1 schematically shows a configuration of an electrophotographic apparatus using a contact charging / transfer member.
FIG. 2 schematically shows an example of a mold / lid used in Example 1 of the present invention, and schematically shows a cross-sectional view in a state in which a core metal and a raw material composition are charged. Is.
FIG. 3 schematically shows an example of a heating plate for carrying out the present invention.
FIG. 4 schematically shows an example of an extruder for carrying out the present invention.
FIG. 5 schematically shows an example of a two-layer extruder for carrying out the present invention.
FIG. 6 schematically shows a measuring apparatus for carrying out resistance measurement in the present invention.
FIG. 7 schematically shows an enlarged view of a three-layer conductive roller according to the present invention.
FIG. 8 schematically shows a two-layer conductive roller according to the present invention.
FIG. 9 schematically shows an enlarged view of a two-layer conductive roller according to the present invention.
FIG. 10 schematically shows an enlarged view of a conductive roller in the present invention.
[Explanation of symbols]
  1 Image carrier
  2 Charging roller
  3 Exposure means
  4 Development member
  5 Transfer roller
  6 Transfer material
  7 Fixing member
  8 Cleaning member
  9 Toner
  10 Mold body
  11 Lid (core metal holding member)
  12 Degassing hole
  13 Unvulcanized raw material composition
  14 Core
  15 Hole to insert mold
  16 Hot plate
  17 Crosshead
  18 Extruder
  19 Core
  20 Unvulcanized composition
  21 Material supply hole
  22 Extruder (for foam layer)
  23 Extruder (for non-foamed layer)
  24 Double-layer crosshead
  25 Conductive roller
  26 Core
  27 Aluminum drum
  28 Power supply
  29 Core
  30 Non-foamed layer
  31 Foam layer
  32 cells
  33 Insulating particles
  34 Insulating particles
  35 Coating layer
  36 Non-foamed layer
  37 Foam layer

Claims (8)

Includes a neighboring Ri suits two conductive layers, a conductive roller insulating particles that are dispersed in both, of the該隣Ri suits two conductive layers, are distributed on the outside of the conductive layer A conductive roller in which the average particle diameter of the insulating particles is 1 μm or more and less than 10 μm, and the average particle diameter of the insulating particles dispersed in the inner conductive layer is 10 μm or more and 50 μm or less . The conductive roller, is arranged in contact with the photosensitive member surface, the conductive roller according to 請 Motomeko 1 Ah Ru in charging roller for charging the photosensitive member surface. A cylindrical inside mold having a lid for holding the metal core in the molding die inner peripheral surface concentric shaft on both ends,
(A) a cored bar,
(B) the polymer material of the foam, a blowing agent, insulating particles and additives are formed by extruding the unvulcanized硫未foaming material compositions kneaded formulated, inner diameter larger than the outer diameter of the core metal and outer diameter is substantially cylindrical smaller than the inner diameter of the cylindrical mold
A step of then placed in co, to form a roller having a foamed layer I by the performing the foaming and vulcanizing a
Forming a coating layer on the outer peripheral surface of the roller using a coating liquid in which insulating particles are dispersed ;
Method for producing a conductive roller that have a. A cylindrical inside mold having a lid for holding the metal core in the molding die inner peripheral surface concentric shaft on both ends,
(A) a cored bar,
(B) the polymer material of the foam, unvulcanized硫未foaming material composition blowing agent and additives were kneaded formulated, as well as polymer material, unvulcanized硫非the insulating particles and the additive are kneaded formulated foaming a raw material composition, which is formed by extruding the same time one one body, the inner diameter rather smaller than the inner diameter larger outer diameter than the outer diameter of the cylindrical mold of the metal core, yet-pressurized a substantially cylindrical stack 硫非foaming material composition outside the yet-pressurized硫未foaming material composition
A step of then placed in co, to form a roller having a non-foamed layer on the vulcanized and foamed layer and foam layer I by the performing the foaming,
Forming a coating layer on the outer peripheral surface of the roller using a coating liquid in which insulating particles are dispersed ;
Method for producing a conductive roller that have a. A cylindrical inside mold having a lid for holding the metal core in the molding die inner peripheral surface concentric shaft on both ends,
(A) a cored bar,
(B) the polymer material of the foam, blowing agents and additives are formed by extruding the unvulcanized硫未foaming material compositions kneaded formulated, inner diameter larger outer diameter than the outer diameter of the core metal is the Insulating particles are coated on the outer peripheral surface of a substantially cylindrical one smaller than the inner diameter of the cylindrical mold.
A step of then placed in co, to form a roller having a foamed layer I by the performing the foaming and vulcanizing a
Forming a coating layer on the outer peripheral surface of the roller using a coating liquid in which insulating particles are dispersed ;
Method for producing a conductive roller that have a. The method for manufacturing a conductive roller according to claim 3, wherein the additive is a conductive agent. The method for producing a conductive roller according to claim 3, wherein a conductive agent is added to the coating liquid. An electrophotographic apparatus having a photoconductor and a charging roller disposed in contact with the surface of the photoconductor for charging the surface of the photoconductor, wherein the charging roller is the conductive roller according to claim 1. A feature of an electrophotographic apparatus.

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