WO2018061441A1 - Charging roll for electrographic device - Google Patents

Charging roll for electrographic device Download PDF

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Publication number
WO2018061441A1
WO2018061441A1 PCT/JP2017/027144 JP2017027144W WO2018061441A1 WO 2018061441 A1 WO2018061441 A1 WO 2018061441A1 JP 2017027144 W JP2017027144 W JP 2017027144W WO 2018061441 A1 WO2018061441 A1 WO 2018061441A1
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WIPO (PCT)
Prior art keywords
particles
diameter particles
small
surface layer
mass
Prior art date
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PCT/JP2017/027144
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French (fr)
Japanese (ja)
Inventor
佐藤　正則
泰秀 渡邊
政典 石田
鵜飼　浩
仁宏 齋藤
Original Assignee
住友理工株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Priority claimed from JP2017035833A external-priority patent/JP6722606B2/en
Application filed by 住友理工株式会社 filed Critical 住友理工株式会社
Priority to CN201780023630.2A priority Critical patent/CN109952540B/en
Publication of WO2018061441A1 publication Critical patent/WO2018061441A1/en
Priority to US15/990,707 priority patent/US20180275552A1/en

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/02—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices

Definitions

  • the present invention relates to a charging roll for an electrophotographic apparatus suitably used in an electrophotographic apparatus such as a copying machine, a printer, a facsimile, etc. which adopts an electrophotographic system.
  • an electrophotographic apparatus as a method of charging the surface of a photosensitive drum, there is known a contact charging method in which a charging roll is brought into direct contact with the surface of the photosensitive drum.
  • a contact charging method in which a charging roll is brought into direct contact with the surface of the photosensitive drum.
  • the contact charging method if the discharge area is narrow, the charge may be concentrated on a local portion, which may cause an image failure. For this reason, as described in, for example, Patent Document 1, particles are added to the surface layer of a charging roll to provide asperities on the surface, thereby securing a discharge region and maintaining a charge amount.
  • a direct current (DC) voltage application system As a system for charging the charging roll, a direct current (DC) voltage application system is known from the viewpoint of downsizing of the apparatus and cost reduction.
  • DC direct current
  • the direct current (DC) voltage application method is inferior in charging property to the alternating current / direct current (AC / DC) superimposed application method.
  • AC / DC alternating current / direct current
  • high-performance devices are required to have high image quality, so charging uniformity is required. For this reason, the prior art can not cope with it.
  • the problem to be solved by the present invention is to provide a charging roll for an electrophotographic apparatus which has high charging performance and satisfactory charging uniformity.
  • a charging roll for an electrophotographic apparatus comprises a shaft, an elastic layer formed on the outer periphery of the shaft, and a surface layer formed on the outer periphery of the elastic layer.
  • the surface layer contains a binder resin, large-diameter particles having an average particle diameter of 15 ⁇ m to 50 ⁇ m, and small-diameter particles having an average particle diameter of 3 ⁇ m to less than 15 ⁇ m, and the content of the small-diameter particles is the binder resin.
  • the gist is that the size of the aggregate of particles including the small diameter particles contained in the surface layer is 6 ⁇ m or more and 50 ⁇ m or less, with respect to 100 parts by mass with 5 to 50 parts by mass.
  • the surface layer preferably contains 0.1 to 10 parts by mass of an organic acid with respect to 100 parts by mass of the binder resin.
  • the organic acid is preferably an organic acid having a hydroxyl group. It is preferable that the difference of the average particle diameter of the said large diameter particle and the said small diameter particle is 10 micrometers or more.
  • the average distance between the small diameter particles is preferably 40 ⁇ m or less.
  • the average distance between the large diameter particles is preferably 60 ⁇ m or more.
  • the hardness of the large diameter particles is preferably smaller than the hardness of the small diameter particles.
  • the small diameter particles are preferably silica particles.
  • the surface layer contains the specific large-diameter particles and the specific small-diameter particles, the content of the small-diameter particles is a specific amount, and condensation of the particles containing the small-diameter particles Since the size of the aggregate is in the specific range, the gap between the photosensitive drum and the photosensitive drum can be sufficiently secured, and the discharge starting point can be uniformly secured. As a result, the charging performance can be enhanced and the uniformity of charging can be satisfied.
  • the surface layer further contains an organic acid
  • it is more excellent in the effect of suppressing the aggregation of large diameter particles.
  • small diameter particles can be efficiently arranged around large diameter particles. Thereby, the size of the aggregate of particles including small diameter particles can be reduced.
  • the organic acid is an organic acid having a hydroxyl group
  • abrasion resistance, discharge resistance and chargeability of the surface layer can be improved.
  • the difference between the average particle size of the large-diameter particles and the small-diameter particles is 10 ⁇ m or more, both the chargeability and the uniformity can be highly achieved. And when the average distance between small diameter particles is 40 ⁇ m or less, the uniformity of charging is further excellent.
  • the uniformity of charging is further excellent. And, when the hardness of the large diameter particles is smaller than the hardness of the small diameter particles, the contamination during the endurance will be further reduced. And when the small diameter particles are silica particles, the contamination during the endurance will be further reduced.
  • FIG. 2 is an enlarged schematic view of the vicinity of the surface of the charging roll for an electrophotographic apparatus shown in FIG.
  • FIG. 1 is a schematic view showing an appearance (a) of the charging roll for an electrophotographic apparatus according to an embodiment of the present invention, and a cross-sectional view along the line AA thereof (b).
  • FIG. 2 is an enlarged schematic view of the vicinity of the surface of the charging roll for an electrophotographic apparatus shown in FIG.
  • the charging roll 10 includes a shaft 12, an elastic layer 14 formed on the outer periphery of the shaft 12, and a surface layer 16 formed on the outer periphery of the elastic layer 14.
  • the elastic layer 14 is a layer to be a base of the charging roll 10.
  • the surface layer 16 is a layer appearing on the surface of the charging roll 10.
  • the surface layer 16 contains a binder resin 22, large diameter particles 18 and small diameter particles 20. Irregularities are formed on the surface of the surface layer 16 by the large diameter particles 18 and the small diameter particles 20.
  • the portion where the large diameter particles 18 are present is a relatively large convex portion, and the portion where the small diameter particles 20 are present is a relatively small convex portion.
  • the relatively small convex portion is disposed one or more or more between the relatively large convex portion and the relatively large convex portion.
  • a relatively large convex portion in which the large diameter particles 18 are present is a portion in contact with the photosensitive drum, and a relatively small convex portion in which the small diameter particles 20 are present is a portion not in contact with the photosensitive drum.
  • the shapes of the large diameter particles 18 and the small diameter particles 20 are not particularly limited, but spherical shapes, spherical shapes and the like are preferable.
  • the large diameter particles 18 are particles having an average particle diameter of 15 ⁇ m to 50 ⁇ m.
  • the large-diameter particles 18 By including such large-diameter particles 18, the surface irregularities of the surface layer 16 become sufficiently large, and the surface layer 16 can sufficiently secure a gap with the photosensitive drum. As a result, the discharge performance is improved, and high chargeability can be ensured.
  • the average particle diameter of the large-diameter particles 18 is less than 15 ⁇ m, the surface layer 16 can not sufficiently secure a gap with the photosensitive drum, and high chargeability can not be secured.
  • the average particle diameter of the large-diameter particles 18 is more than 50 ⁇ m, the charging uniformity can not be satisfied.
  • the average particle diameter of the large-diameter particles 18 is more preferably 20 ⁇ m or more, and further preferably 25 ⁇ m or more from the viewpoint that the gap between the large-diameter particles 18 and the photosensitive drum can be increased.
  • the average particle diameter of the large-diameter particles 18 is more preferably 45 ⁇ m or less, and still more preferably 40 ⁇ m or less, from the viewpoint of easily increasing the uniformity of charging.
  • the average particle diameter of the large diameter particles 18 is a median diameter measured by a laser diffraction / scattering particle diameter distribution measuring apparatus.
  • the large diameter particles 18 are not particularly limited, but resin particles are preferable from the viewpoint of easily securing the flexibility at the contact portion with the photosensitive drum.
  • resin particles acrylic particles, urethane particles, polyamide particles and the like can be mentioned.
  • the large diameter particles 18 may be composed of one of these resin particles, or may be composed of two or more kinds of resin particles.
  • acrylic particles are preferable from the viewpoint of low fixation and the like due to a low deformation rate.
  • polyamide particles nylon particles
  • the large-diameter particles 18 preferably have a small amount of deformation with respect to load, from the viewpoint of easily maintaining the gap between the large-diameter particles 18 and the photosensitive drum.
  • the deformation amount is preferably 80% or less. More preferably, it is 70% or less, more preferably 60% or less.
  • the amount of deformation is 10% or more from the viewpoint of securing flexibility and the like. More preferably, it is 20% or more.
  • the content of the large diameter particles 18 is not particularly limited, but from the viewpoint of appropriately securing the interparticle distance of the large diameter particles 18 and easily enhancing the uniformity of charging, 100 of the binder resin 22 It is preferably in the range of 5 to 40 parts by mass with respect to the parts by mass. More preferably, it is in the range of 5 to 35 parts by mass, more preferably in the range of 10 to 30 parts by mass.
  • the average distance between the large diameter particles 18 is preferably 60 ⁇ m or more.
  • the amount of the large diameter particles 18 is appropriate, and the uniformity of the charge can be easily improved.
  • the average distance between the large diameter particles 18 is more preferably 80 ⁇ m or more, and further preferably 100 ⁇ m or more.
  • the average distance between the large diameter particles 18 is preferably 300 ⁇ m or less from the viewpoint that the amount of the large diameter particles 18 becomes appropriate and the uniformity of charging can be easily improved. More preferably, it is 250 micrometers or less, More preferably, it is 200 micrometers or less.
  • the average distance between the large diameter particles 18 is obtained by taking a surface photograph of the surface layer 16 and measuring three distances between the large diameter particles 18 at any five points, and is represented by an average of 15 points in total.
  • the distance between the large diameter particles 18 is represented by the distance between the outer circumferences facing each other.
  • the large diameter particles 18 and the large diameter particles 18 be present without forming an aggregate from the viewpoint of easily maintaining the gap between the photosensitive member and the like uniformly.
  • the small diameter particles 20 are particles having an average particle diameter of 3 ⁇ m or more and less than 15 ⁇ m.
  • the convex part of the part in which the small diameter particle 20 exists becomes an origin of discharge.
  • the surface layer 16 secures the starting point of the discharge, and the uniformity of the charging can be satisfied by the small diameter particles 20 being dispersed. If the average particle diameter of the small-diameter particles 20 is less than 3 ⁇ m, the convex portion in the portion where the small-diameter particles 20 are present is too small to be a starting point of the discharge, and charging uniformity can not be satisfied.
  • the average particle diameter of the small diameter particles 20 is more than 15 ⁇ m, the convex portion of the portion where the small diameter particles 20 are present is too large to be a starting point of the discharge, and charging uniformity can not be satisfied.
  • the average particle diameter of the small-diameter particles 20 is more preferably 4 ⁇ m or more, and further preferably 5 ⁇ m or more from the viewpoint of improving the uniformity of charging. Moreover, More preferably, it is 10 micrometers or less, More preferably, it is 7 micrometers or less.
  • the average particle diameter of the small diameter particles 20 is a median diameter measured by a laser diffraction / scattering particle diameter distribution measuring apparatus.
  • the small-diameter particles 20 may be resin particles excellent in flexibility or relatively hard inorganic particles because they are disposed in the non-contact portion with the photosensitive drum.
  • relatively hard inorganic particles are preferable from the viewpoint of, for example, increasing the difference in hardness with the large-diameter particles 18 to easily reduce stains during durability.
  • silica particles are particularly preferable from the viewpoint of further reducing contamination during durability.
  • the content of the small diameter particles 20 is in the range of 5 to 50 parts by mass with respect to 100 parts by mass of the binder resin 22. If the content of the small-diameter particles 20 is less than 5 parts by mass, the starting point of the discharge is small, and the uniformity of charging can not be ensured. When the content of the small diameter particles 20 is more than 50 parts by mass, the small diameter particles 20 are too large to suppress aggregation of the particles including the small diameter particles 20, and the aggregates of the particles including the small diameter particles 20 become too large to be charged. Uniformity can not be ensured.
  • the content of the small diameter particles 20 is more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, with respect to 100 parts by mass of the binder resin 22 from the above viewpoint. Further, from the above viewpoint, the amount is more preferably 40 parts by mass or less, still more preferably 30 parts by mass or less with respect to 100 parts by mass of the binder resin 22.
  • the average distance between the small diameter particles 20 is preferably 40 ⁇ m or less.
  • the average distance between the small-diameter particles 20 is obtained by taking a surface photograph of the surface layer 16 and measuring three distances between the small-diameter particles 20 at any five points, and is represented by an average of a total of 15 points.
  • the distance between the small diameter particles 20 is represented by the distance between the outer circumferences facing each other.
  • aggregates of particles including the small diameter particles 20 there may be no aggregates of particles including the small diameter particles 20, but as shown in FIG. 2 (b), aggregates of particles including the small diameter particles 20. May be included.
  • an aggregate of particles including the small diameter particles 20 there are an aggregate of particles including both the small diameter particles 20 and the large diameter particles 18, and an aggregate of particles consisting of only the small diameter particles 20.
  • Each of the aggregate 24c of the particle which consists of one of the large diameter particle 18 is shown.
  • the aggregation of the small diameter particles 20 and the aggregation of the large diameter particles 18 are suppressed to appropriately disperse the small diameter particles 20 and the large diameter particles 18 Cheap. It is preferable in terms of discharge control that there is an aggregate of particles consisting of only the small diameter particles 20.
  • the size of the aggregate of particles including the small diameter particles 20 is 6 ⁇ m or more and 50 ⁇ m or less. Since the dispersibility of the particles is excellent, the uniformity of charging can be satisfied. If the size of the aggregate is more than 50 ⁇ m, the dispersibility of the particles is poor, and the uniformity of charging can not be satisfied. Further, from this viewpoint, the size of the aggregate is preferably 45 ⁇ m or less, more preferably 40 ⁇ m or less.
  • the aggregate of particles including the small diameter particles 20 is an aggregate of particles collected in a plane along the surface of the elastic layer 14, and there is little stacking in the thickness direction due to the amount and thickness of the binder resin 22 and the like.
  • the size of the aggregate of particles including the small diameter particles 20 is a photograph of the surface of the surface layer 16 and the maximum distance of three aggregates of the particles including the small diameter particles 20 is measured at any five points, and a total of 15 points Expressed by the average of
  • the difference in average particle size between the large diameter particles 18 and the small diameter particles 20 is preferably 10 ⁇ m or more. As the difference in average particle size is larger, the surface unevenness of the surface layer 16 becomes larger, and the surface layer 16 can easily secure a gap with the photosensitive drum. From this viewpoint, the difference in average particle size is more preferably 15 ⁇ m or more, and further preferably 20 ⁇ m or more.
  • the hardness of the large diameter particles 18 is preferably smaller than the hardness of the small diameter particles 20.
  • the relationship between the hardness a of the large diameter particles 18 and the hardness b of the small diameter particles 20 is preferably a / b ⁇ 1. More preferably, a / b ⁇ 0.7, still more preferably a / b ⁇ 0.6, and particularly preferably a / b ⁇ 0.5.
  • the height of the convex part in the part in which the large diameter particle 18 exists is 10 micrometers or more. More preferably, it is 15 micrometers or more, More preferably, it is 20 micrometers or more.
  • the height of the convex portion is 10 ⁇ m or more, it is easy to secure a gap between the convex portion and the photosensitive drum.
  • the height of the convex part in the part in which the small diameter particle 20 exists is 2.0 micrometers or more. More preferably, it is 2.5 micrometers or more, More preferably, it is 3.0 micrometers or more. It is easy to ensure the starting point of discharge as the height of this convex part is 2.0 micrometers or more.
  • the height of the convex portion is represented by the height from the surface of the surface layer 16 in a portion where no particle is present (for example, a portion between the small particle 20 and the small particle 20).
  • the height of the convex portion can be measured by observing the cross section using a laser microscope (for example, “VK-9510” manufactured by Keyence Corporation).
  • the heights of the projections can be measured at five positions at arbitrary positions, and the heights can be represented by the average thereof.
  • the binder resin 22 is not particularly limited, and a suitable material may be selected according to the required characteristics and the like.
  • the binder include acrylic resins, methacrylic resins, fluorine resins, silicone resins, polycarbonate resins, urethane resins, and polyamide resins. These may be used singly as the binder resin 22 of the surface layer 16 or may be used in combination of two or more. Among these, polyamide resins and acrylic resins are more preferable from the viewpoint of resistance control, flexibility and the like.
  • the binder resin 22 is preferably made of the same material as that of the particles from the viewpoint of adhesion to the particles and the like.
  • the surface layer 16 may contain an organic acid in addition to the binder resin 22, the large diameter particles 18, and the small diameter particles 20.
  • the organic acid is ionized in the composition for surface layer formation. The presence of the ionized organic acid around the particles allows the particles to have a negative charge that the organic acid has. Since the large diameter particles 18 having a larger surface area have more negative charges than the small diameter particles 20, the large diameter particles 18 are likely to cause electrostatic repulsion. For this reason, when the surface layer 16 further contains an organic acid, it is surmised that the surface layer 16 is more excellent in the effect of suppressing the aggregation of the large diameter particles 18 with each other.
  • the small diameter particle 20 has a smaller negative charge than the large diameter particle 18, the electrostatic repulsion between the large diameter particle 18 and the small diameter particle 20 is small, and the large diameter particle 18 and the small diameter particle 20 are Can aggregate.
  • the surface layer 16 further contains an organic acid, it is presumed that the small diameter particles 20 can be efficiently arranged around the large diameter particles 18. Further, the electrostatic repulsion between the small diameter particles 20 reduces the number of the small diameter particles 20 disposed around the large diameter particles 18.
  • the surface layer 16 further contains the organic acid, the size of the aggregate of particles including the small diameter particles 20 can be suppressed to a small size.
  • Examples of the organic acid include carboxylic acid and sulfonic acid.
  • Examples of carboxylic acids include citric acid, oxalic acid, acetic acid, formic acid and the like. These may be used alone as an organic acid to be added to the surface layer 16 or may be used in combination of two or more. Among these, carboxylic acids are preferable, and organic acids having a hydroxyl group such as citric acid and oxalic acid are particularly preferable.
  • the organic acid is an organic acid having a hydroxyl group, the abrasion resistance, the discharge resistance and the chargeability of the surface layer 16 can be improved.
  • the hydroxyl group of the organic acid is likely to form a hydrogen bond with the amide group of nylon as the binder resin, the carbonyl group of the acrylic resin, etc., and it is speculated that the abrasion resistance and discharge resistance of the surface layer 16 will be improved by the hydrogen bond interaction. Ru. Further, it is presumed that the chargeability is improved by the increase in the capacitance of the surface layer 16 due to the hydroxyl group of the organic acid.
  • the content of the organic acid is excellent in the effect of suppressing the cohesion of the large diameter particles 18, efficiently arranges the small diameter particles 20 around the large diameter particles 18, and reduces the size of the aggregate of particles including the small diameter particles 20. It is preferable that it is 0.1 mass part or more with respect to 100 mass parts of binder resin from a viewpoint of suppressing. More preferably, it is 0.5 parts by mass or more. In addition, the content of the organic acid is preferably 10 parts by mass or less with respect to 100 parts by mass of the binder resin from the viewpoint of the compatibility of the organic acid or the diluted solution of the organic acid in the composition for surface layer formation. More preferably, it is 7 parts by mass or less.
  • the surface layer 16 may or may not contain an additive in addition to the binder resin 22, the large diameter particles 18, and the small diameter particles 20.
  • the additive include a conductive agent, a stabilizer, an ultraviolet light absorber, a lubricant, a release agent, a dye, a pigment, a flame retardant and the like.
  • the conductive agent include ion conductive agents (quaternary ammonium salts and the like) and electron conductive agents (carbon black and the like).
  • the surface layer 16 can be adjusted to a predetermined volume resistivity by the type of material, the composition of the conductive agent, and the like.
  • the volume resistivity of the surface layer 16 may be appropriately set in the range of 10 5 to 10 11 ⁇ ⁇ cm, 10 8 to 10 10 ⁇ ⁇ cm, or the like depending on the application and the like.
  • the thickness of the surface layer 16 is represented by the thickness in the part where particles do not exist (for example, the part between the small diameter particles 20 and the small diameter particles 20).
  • the thickness of the surface layer 16 is preferably 1.0 ⁇ m or more from the viewpoint of easily fixing the large-diameter particles 18 and the small-diameter particles 20 in the surface layer. More preferably, it is 1.5 ⁇ m or more.
  • the diameter is preferably 3.0 ⁇ m or less from the viewpoint of securing the size of the convex portion in the portion where the small diameter particles 20 are present and easily securing the starting point of the discharge. More preferably, it is 2.5 ⁇ m or less.
  • the thickness of the surface layer 16 can be measured by observing the cross section using a laser microscope (for example, "VK-9510" manufactured by Keyence Corporation). For example, the distance from the surface of the elastic layer 14 to the surface of the surface layer 16 can be measured at five positions in any position, and can be represented by the average.
  • the surface layer 16 is formed by applying the composition for forming a surface layer including the binder resin 22, the large diameter particles 18, and the small diameter particles 20 to the outer peripheral surface of the elastic layer 14 and performing drying treatment etc. as appropriate. be able to.
  • the binder resin 22, the large diameter particles 18, and the small diameter particles 20 can be prepared as a dispersion using a dispersion medium.
  • ketone solvents such as methyl ethyl ketone (MEK) and methyl isobutyl ketone
  • alcohol solvents such as isopropyl alcohol (IPA), methanol and ethanol
  • hydrocarbon solvents such as hexane and toluene, ethyl acetate, butyl acetate and the like
  • ether solvents such as diethyl ether and tetrahydrofuran, water and the like.
  • the composition for surface layer formation fully disperses particles before coating.
  • the particles can be sufficiently dispersed before coating by irradiating the composition for forming a surface layer with ultrasonic waves.
  • the composition for surface layer formation containing an organic acid can fully disperse
  • the composition for surface layer formation containing an organic acid can reduce or reduce the process of irradiating ultrasonic waves.
  • the elastic layer 14 contains a crosslinked rubber.
  • the elastic layer 14 is formed of a conductive rubber composition containing uncrosslinked rubber.
  • Crosslinked rubber is obtained by crosslinking uncrosslinked rubber.
  • the uncrosslinked rubber may be a polar rubber or a nonpolar rubber. From the viewpoint of excellent conductivity etc., the non-crosslinked rubber is more preferably a polar rubber.
  • the polar rubber is a rubber having a polar group, and examples of the polar group include chloro group, nitrile group, carboxyl group and epoxy group.
  • Specific examples of polar rubbers include hydrin rubber, nitrile rubber (NBR), urethane rubber (U), acrylic rubber (copolymer of acrylic ester and 2-chloroethyl vinyl ether, ACM), chloroprene rubber (CR) And epoxidized natural rubber (ENR).
  • NBR nitrile rubber
  • U urethane rubber
  • acrylic rubber copolymer of acrylic ester and 2-chloroethyl vinyl ether, ACM
  • chloroprene rubber CR
  • EMR epoxidized natural rubber
  • a hydrin rubber and a nitrile rubber (NBR) are more preferable from the viewpoint that the volume resistivity tends to be particularly low.
  • hydrin rubbers examples include epichlorohydrin homopolymer (CO), epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-allyl glycidyl ether binary copolymer (GCO), epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary A copolymer (GECO) etc. can be mentioned.
  • CO epichlorohydrin homopolymer
  • ECO epichlorohydrin-ethylene oxide binary copolymer
  • GCO epichlorohydrin-allyl glycidyl ether binary copolymer
  • GECO epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary A copolymer
  • the polyether-type urethane rubber which has an ether bond in a molecule
  • numerator can be mentioned.
  • the polyether type urethane rubber can be produced by the reaction of a polyether having a hydroxyl group at both ends with a diisocyanate.
  • the polyether is not particularly limited, and polyethylene glycol, polypropylene glycol and the like can be mentioned. Although it does not specifically limit as diisocyanate, Tolylene diisocyanate, diphenylmethane diisocyanate etc. can be mentioned.
  • nonpolar rubbers examples include isoprene rubber (IR), natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR) and the like.
  • crosslinking agent a sulfur crosslinking agent, a peroxide crosslinking agent, and a dechlorination crosslinking agent can be mentioned. These crosslinking agents may be used alone or in combination of two or more.
  • sulfur crosslinking agents include conventionally known sulfur crosslinking agents such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, sulfur chloride, thiuram vulcanization accelerator, and polymeric polysulfides. it can.
  • peroxide crosslinking agents include conventionally known peroxide crosslinking agents such as peroxy ketals, dialkyl peroxides, peroxy esters, ketone peroxides, peroxy dicarbonates, diacyl peroxides and hydroperoxides. Can.
  • a dithiocarbonate compound As a dechlorination crosslinking agent, a dithiocarbonate compound can be mentioned. More specifically, quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-dithiocarbonate, 6-isopropylquinoxaline-2,3-dithiocarbonate, 5,8-dimethylquinoxaline-2,3- A dithio carbonate etc. can be mentioned.
  • the compounding amount of the crosslinking agent is preferably in the range of 0.1 to 2 parts by mass, more preferably 0.3 to 1.8 parts by mass with respect to 100 parts by mass of the non-crosslinked rubber from the viewpoint of hardly bleeding or the like. Within the range of part, more preferably within the range of 0.5 to 1.5 parts by mass.
  • a dechlorination crosslinking accelerator may be used in combination.
  • a dechlorination crosslinking accelerator 1,8-diazabicyclo (5,4,0) undecen-7 (hereinafter abbreviated as DBU) or a weak acid salt thereof can be mentioned.
  • DBU 1,8-diazabicyclo (5,4,0) undecen-7
  • the dechlorination crosslinking accelerator may be used in the form of DBU, it is preferably used in the form of its weak acid salt from the viewpoint of its handling.
  • the content of the dechlorination crosslinking accelerator is preferably in the range of 0.1 to 2 parts by mass with respect to 100 parts by mass of the uncrosslinked rubber, from the viewpoint of hardly bleeding. More preferably, it is in the range of 0.3 to 1.8 parts by mass, still more preferably in the range of 0.5 to 1.5 parts by mass.
  • the elastic layer 14 is made of carbon black, graphite, c-TiO 2 , c-ZnO, c-SnO 2 (c-means conductivity), an ion conductive agent (quaternary) to impart conductivity.
  • Conventionally known conductive agents such as ammonium salts, borates, surfactants and the like can be added as appropriate.
  • various additives may be added as appropriate.
  • additives lubricants, vulcanization accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, foaming agents, fillers, dispersants, antifoam agents, pigments, release agents Examples include molds and the like.
  • the elastic layer 14 can be adjusted to a predetermined volume resistivity by the type of crosslinked rubber, the compounding amount of the ion conductive agent, the compounding of the electron conductive agent, and the like.
  • the volume resistivity of the elastic layer 14 may be appropriately set in the range of 10 2 to 10 10 ⁇ ⁇ cm, 10 3 to 10 9 ⁇ ⁇ cm, 10 4 to 10 8 ⁇ ⁇ cm, etc. depending on the application etc. .
  • the thickness of the elastic layer 14 is not particularly limited, and may be appropriately set in the range of 0.1 to 10 mm according to the application and the like.
  • the elastic layer 14 can be manufactured, for example, as follows. First, the shaft 12 is coaxially installed in the hollow portion of the roll forming mold, and the uncrosslinked conductive rubber composition is injected, heated and cured (crosslinked), and then removed or The elastic layer 14 is formed on the outer periphery of the shaft 12 by extruding an uncrosslinked conductive rubber composition on the surface of the shaft 12 or the like.
  • the shaft 12 is not particularly limited as long as it has conductivity. Specifically, a solid body made of metal such as iron, stainless steel, or aluminum, a cored bar made of a hollow body, and the like can be exemplified. An adhesive, a primer or the like may be applied to the surface of the shaft 12 as necessary. That is, the elastic layer 14 may be bonded to the shaft 12 via the adhesive layer (primer layer). The adhesive, the primer, etc. may be made conductive as required.
  • the surface layer 16 contains the specific large-diameter particles 18 and the specific small-diameter particles 20, and the content of the small-diameter particles 20 is a specific amount. Since the size of the aggregate is within the specific range, the gap between the aggregate and the photosensitive drum can be sufficiently secured, and the discharge starting point can be uniformly secured. As a result, the charging performance can be enhanced and the uniformity of charging can be satisfied.
  • the configuration of the charging roll according to the present invention is not limited to the configuration shown in FIG.
  • another elastic layer may be provided between the shaft 12 and the elastic layer 14.
  • the other elastic layer is a layer to be a base of the charging roll, and the elastic layer 14 functions as a resistance adjusting layer or the like for adjusting the resistance of the charging roll.
  • the other elastic layer can be made of, for example, any of the materials mentioned as the material of the elastic layer 14.
  • another elastic layer may be provided between the elastic layer 14 and the surface layer 16.
  • the elastic layer 14 is a layer to be a base of the charging roll, and the other elastic layers function as a resistance adjusting layer or the like for adjusting the resistance of the charging roll.
  • Examples 1 to 11, Comparative Examples 1 to 8) ⁇ Preparation of Conductive Rubber Composition> Based on 100 parts by mass of isoprene rubber, 30 parts by mass of carbon black, 6 parts by mass of zinc oxide, 2 parts by mass of stearic acid, 1 part by mass of sulfur, 0.5 parts by mass of thiazole based vulcanization accelerator, 0 thiraum based vulcanization accelerator A conductive rubber composition was prepared by blending 5 parts by mass and 50 parts by mass of ground calcium carbonate, and kneading for 10 minutes using a closed-type mixer whose temperature was adjusted to 50 ° C.
  • -Rubber component Isoprene rubber (IR) [manufactured by JSR Corp., "JSR IR 2200”] ⁇ Conductive agent carbon black (electronic conductive agent) [Cabot Japan KK, “Show Black N762”] ⁇ Zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., “Zinc oxide 2”) ⁇ Stearic acid (manufactured by NOF Corp., “Stearic Acid Sakura”) ⁇ Sulfur [made by Tsurumi Chemical Industries, Ltd., “powdered sulfur”] ⁇ Vulcanization accelerator Thiazole-based vulcanization accelerator [Ouchi Shinko Chemical Co., Ltd.
  • the prepared conductive rubber composition was extruded into a crown shape around the periphery of a core metal made of free-cutting steel (SUM) with a diameter of 6 mm.
  • the conductive rubber composition is supplied to the gap between the die and the cored bar while passing the cored bar to the circular opening of the die of the extrusion molding apparatus, whereby the outer periphery of the cored bar is made elastic.
  • the body layer was extruded.
  • the shape of the elastic layer precursor is made into a crown shape by changing the passing speed of the core metal and controlling the adhesion amount of the conductive rubber composition in the longitudinal direction of the core metal. It was then heat treated at 180 ° C. for 30 minutes. Thereby, a predetermined elastic layer (thickness 1.5 mm) was formed on the outer periphery of the cored bar.
  • ⁇ Preparation of surface> The particles and the binder resin are blended so that the blending amounts (mass parts) described in Tables 1 and 2 are added, 200 parts by mass of methyl ethyl ketone (MEK) is added, and ultrasonic waves are applied for a predetermined time to mix and stir.
  • a liquid composition for formation was prepared. Next, the liquid composition was roll-coated on the outer peripheral surface of the elastic layer, and heat treatment was performed to form a surface layer on the outer periphery of the elastic layer. Thereby, a charging roll was produced.
  • Example 12 to 18 The particles, the binder resin and the organic acid solution are blended so as to be the blending amount (mass part) described in Table 3, 200 parts by mass of methyl ethyl ketone (MEK) is added, and the surface layer is mixed and stirred for a predetermined time (10 minutes). A liquid composition for formation was prepared. At this time, ultrasound was not applied. A charge roll was produced in the same manner as in the other examples except that the obtained composition for surface layer formation was used.
  • MEK methyl ethyl ketone
  • each measurement was performed about the used particle. Moreover, each measurement was performed about the surface layer of each produced charging roll. And the image evaluation related to chargeability was performed about each produced charging roll. In addition, the durability was also evaluated. In Examples 1, 7 and 12 to 18, the number of aggregates of large diameter particles was examined, and image evaluation after durability was performed. The evaluation results and the composition of the surface layer forming composition are shown in the following table.
  • the hardness ratio of particles Using a "Fisherscope HM2000LT” manufactured by Fischer Co. or an equivalent measuring instrument, using a planar indenter, the universal hardness (HU) when 1 mN was pressed into the particles was taken as the measured value.
  • Deformation amount of particle It measured with the universal hardness tester. The particle size was calculated from the particle size when a pressing load of 50 mN was applied and the particle size before the load was applied.
  • Size of particle aggregates The size of the aggregate of particles containing small-diameter particles, take a picture of the surface of the surface layer, measure the maximum distance of three aggregates of particles containing small-diameter particles at any five locations, and average the total of 15 points expressed.
  • the average distance between the large diameter particles was obtained by taking a surface photograph of the surface layer, measuring the distance between three large diameter particles at any five points, and expressing the average of a total of 15 points. The average distance between small particles and the average distance between other particles were also measured.
  • the height of the convex portion of the large diameter particle portion was represented by the height from the surface of the surface layer in the portion where no particle is present to the surface of the surface portion of the top in the portion where the large diameter particle is present.
  • the heights of the convex portions of the large diameter particle portions were measured at five positions at arbitrary positions, and the heights were expressed by the average.
  • the heights of the protrusions of the small diameter particles and the heights of the protrusions of the other particles were also measured.
  • Comparative Examples 1 and 2 contain predetermined large-diameter particles but do not contain predetermined small-diameter particles, and therefore the charging uniformity is insufficient and the image uniformity is inferior.
  • Comparative Example 3 contains predetermined small-diameter particles but does not contain predetermined large-diameter particles, so the gap between the photosensitive drum and the photosensitive drum is insufficient, and a lateral streak occurs in the image.
  • Comparative Example 4 contains predetermined large-diameter particles and predetermined small-diameter particles, but since the content of predetermined small-diameter particles is too small, charging uniformity is insufficient and image uniformity is poor.
  • Comparative Example 5 contains predetermined large-sized particles and particles having a diameter larger than that of the large-sized particles, but does not contain predetermined small-sized particles, so charging uniformity is insufficient and image uniformity is inferior.
  • Comparative Example 6 includes particles having a diameter smaller than a predetermined small particle and predetermined large particles but does not contain a predetermined small particle, so charging uniformity is insufficient and image uniformity is inferior.
  • Comparative Example 7 although the content of the predetermined small diameter particles is too large although the predetermined large diameter particles and the predetermined small diameter particles are included, the size of the aggregate including the small diameter particles is too large and the charging uniformity is insufficient. Is inferior to the uniformity of the image.
  • Comparative Example 8 contains predetermined large-diameter particles and predetermined small-diameter particles, but the dispersion by ultrasonic waves is insufficient. Therefore, the size of the aggregate including small-diameter particles is too large, and charging uniformity is insufficient. Poor in image uniformity.
  • the content of the predetermined small diameter particles is within the predetermined range, and the size of the aggregate of the particles including the small diameter particles is within the predetermined range. Therefore, the gap between the photosensitive drum and the photosensitive drum was sufficiently secured and the charging uniformity was also satisfactory, and no lateral streaks occurred in the image, and the uniformity of the image was also excellent. Also, the durability was excellent. And in comparison of Examples, when the hardness ratio of a large diameter particle and a small diameter particle is 0.5 or less, the dirt at the time of endurance decreases further, and it turns out that it is excellent in especially endurance.
  • Example 1 From the comparison of Example 1 with Examples 12 to 17, Example 7 with Example 18 and Comparative Example 8, when the surface layer further contains an organic acid, an aggregate of particles including small diameter particles even without applying ultrasonic waves.
  • the size can be kept small. Moreover, aggregation of large diameter particles can be suppressed. In addition, the distance between the large diameter particles can be further increased. As a result, improvement in image quality and reduction in roll contamination were confirmed.

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Abstract

Provided is a charging roll for an electrographic device in which charge capability is increased and uniformity of charging is satisfied. A charging roll 10 for an electrographic device, the charging roll being provided with a shaft body 12, an elastic body layer 14 formed on the outer periphery of the shaft body 12, and a surface layer 16 formed on the outer periphery of the elastic body layer 14, the surface layer 16 containing a binder resin, large-diameter particles 18 having an average particle diameter of 15-50 μm, and small-diameter particles 20 having an average particle diameter of 3 μm or more and less than 15 μm, the content of the small-diameter particles 20 being within the range of 5-50 mass parts to 100 mass parts of the binder resin, and the size of the aggregates of particles including the small-diameter particles 20 contained in the surface layer 16 being 6-50 μm.

Description

電子写真機器用帯電ロールCharging roller for electrophotographic equipment
　本発明は、電子写真方式を採用する複写機、プリンター、ファクシミリなどの電子写真機器において好適に用いられる電子写真機器用帯電ロールに関するものである。 The present invention relates to a charging roll for an electrophotographic apparatus suitably used in an electrophotographic apparatus such as a copying machine, a printer, a facsimile, etc. which adopts an electrophotographic system.
　電子写真機器において、感光ドラムの表面を帯電させる方式としては、帯電ロールを感光ドラムの表面に直接接触させる接触帯電方式が知られている。接触帯電方式においては、放電領域が狭いと局部に帯電が集中して画像不具合が生じるおそれがある。このため、例えば特許文献１に記載されるように、帯電ロールの表層に粒子を添加して表面に凹凸を設けることで放電領域を確保し、帯電量を維持することが行われている。 In an electrophotographic apparatus, as a method of charging the surface of a photosensitive drum, there is known a contact charging method in which a charging roll is brought into direct contact with the surface of the photosensitive drum. In the contact charging method, if the discharge area is narrow, the charge may be concentrated on a local portion, which may cause an image failure. For this reason, as described in, for example, Patent Document 1, particles are added to the surface layer of a charging roll to provide asperities on the surface, thereby securing a discharge region and maintaining a charge amount.
特開２００９－１７５４２７号公報JP, 2009-175427, A
　帯電ロールを帯電させる方式としては、装置のコンパクト化、低コスト化などから、直流（ＤＣ）電圧印加方式が知られている。近年、高速機や高機能機にも直流（ＤＣ）電圧印加方式を採用する試みがなされている。しかし、直流（ＤＣ）電圧印加方式は、交流／直流（ＡＣ／ＤＣ）重畳印加方式に比べて帯電性が劣る。高速機は帯電ロールと感光ドラムの接地時間が短くなるため、帯電性が悪化する。また、高機能機は高画質が要求されるため、帯電の均一性が求められる。このため、従来の技術では対応できなくなってきている。 As a system for charging the charging roll, a direct current (DC) voltage application system is known from the viewpoint of downsizing of the apparatus and cost reduction. In recent years, attempts have been made to adopt a direct current (DC) voltage application method to high-speed machines and high-performance machines. However, the direct current (DC) voltage application method is inferior in charging property to the alternating current / direct current (AC / DC) superimposed application method. In the high-speed machine, the contact time between the charging roll and the photosensitive drum is shortened, so the chargeability is deteriorated. In addition, high-performance devices are required to have high image quality, so charging uniformity is required. For this reason, the prior art can not cope with it.
　本発明が解決しようとする課題は、帯電性能を高くするとともに帯電の均一性も満足する電子写真機器用帯電ロールを提供することにある。 The problem to be solved by the present invention is to provide a charging roll for an electrophotographic apparatus which has high charging performance and satisfactory charging uniformity.
　上記課題を解決するため本発明に係る電子写真機器用帯電ロールは、軸体と、前記軸体の外周に形成された弾性体層と、前記弾性体層の外周に形成された表層と、を備え、前記表層は、バインダー樹脂と、平均粒子径１５μｍ以上５０μｍ以下の大径粒子と、平均粒子径３μｍ以上１５μｍ未満の小径粒子と、を含有し、前記小径粒子の含有量が、前記バインダー樹脂１００質量部に対し、５～５０質量部の範囲内であり、前記表層に含まれる前記小径粒子を含む粒子の凝集体の大きさが６μｍ以上５０μｍ以下であることを要旨とするものである。 In order to solve the above problems, a charging roll for an electrophotographic apparatus according to the present invention comprises a shaft, an elastic layer formed on the outer periphery of the shaft, and a surface layer formed on the outer periphery of the elastic layer. The surface layer contains a binder resin, large-diameter particles having an average particle diameter of 15 μm to 50 μm, and small-diameter particles having an average particle diameter of 3 μm to less than 15 μm, and the content of the small-diameter particles is the binder resin. The gist is that the size of the aggregate of particles including the small diameter particles contained in the surface layer is 6 μm or more and 50 μm or less, with respect to 100 parts by mass with 5 to 50 parts by mass.
　前記表層は、前記バインダー樹脂１００質量部に対し、有機酸を０．１～１０質量部含有することが好ましい。前記有機酸は、水酸基を有する有機酸であることが好ましい。前記大径粒子と前記小径粒子の平均粒子径の差は、１０μｍ以上であることが好ましい。前記小径粒子間の平均距離は、４０μｍ以下であることが好ましい。前記大径粒子間の平均距離は、６０μｍ以上であることが好ましい。前記大径粒子の硬度は、前記小径粒子の硬度よりも小さいことが好ましい。前記小径粒子は、シリカ粒子であることが好ましい。 The surface layer preferably contains 0.1 to 10 parts by mass of an organic acid with respect to 100 parts by mass of the binder resin. The organic acid is preferably an organic acid having a hydroxyl group. It is preferable that the difference of the average particle diameter of the said large diameter particle and the said small diameter particle is 10 micrometers or more. The average distance between the small diameter particles is preferably 40 μm or less. The average distance between the large diameter particles is preferably 60 μm or more. The hardness of the large diameter particles is preferably smaller than the hardness of the small diameter particles. The small diameter particles are preferably silica particles.
　本発明に係る電子写真機器用帯電ロールによれば、表層が、特定の大径粒子と特定の小径粒子とを含有し、小径粒子の含有量が特定量であり、小径粒子を含む粒子の凝集体の大きさが特定範囲とされていることから、感光ドラムとの間のギャップを十分に確保することができるとともに、放電の起点を均一に確保することができる。これにより、帯電性能を高くすることができるとともに帯電の均一性も満足することができる。 According to the charging roll for an electrophotographic apparatus according to the present invention, the surface layer contains the specific large-diameter particles and the specific small-diameter particles, the content of the small-diameter particles is a specific amount, and condensation of the particles containing the small-diameter particles Since the size of the aggregate is in the specific range, the gap between the photosensitive drum and the photosensitive drum can be sufficiently secured, and the discharge starting point can be uniformly secured. As a result, the charging performance can be enhanced and the uniformity of charging can be satisfied.
　表層がさらに有機酸を含有すると、大径粒子同士の凝集を抑える効果により優れる。また、効率良く大径粒子の周りに小径粒子を配置することができる。これにより、小径粒子を含む粒子の凝集体の大きさを小さく抑えることができる。有機酸が水酸基を有する有機酸であると、表層の耐摩耗性、耐放電性、荷電性を向上することができる。大径粒子と小径粒子の平均粒子径の差が１０μｍ以上であると、帯電性と均一性を高度に両立することができる。そして、小径粒子間の平均距離が４０μｍ以下であると、帯電の均一性に一層優れる。そして、大径粒子間の平均距離が６０μｍ以上であると、帯電の均一性に一層優れる。そして、大径粒子の硬度が小径粒子の硬度よりも小さいと、耐久時の汚れが一層低減する。そして、小径粒子がシリカ粒子であると、耐久時の汚れが一層低減する。 When the surface layer further contains an organic acid, it is more excellent in the effect of suppressing the aggregation of large diameter particles. In addition, small diameter particles can be efficiently arranged around large diameter particles. Thereby, the size of the aggregate of particles including small diameter particles can be reduced. When the organic acid is an organic acid having a hydroxyl group, abrasion resistance, discharge resistance and chargeability of the surface layer can be improved. When the difference between the average particle size of the large-diameter particles and the small-diameter particles is 10 μm or more, both the chargeability and the uniformity can be highly achieved. And when the average distance between small diameter particles is 40 μm or less, the uniformity of charging is further excellent. And when the average distance between large diameter particles is 60 μm or more, the uniformity of charging is further excellent. And, when the hardness of the large diameter particles is smaller than the hardness of the small diameter particles, the contamination during the endurance will be further reduced. And when the small diameter particles are silica particles, the contamination during the endurance will be further reduced.
本発明の一実施形態に係る電子写真機器用帯電ロールの外観模式図（ａ）と、そのＡ－Ａ線断面図（ｂ）である。BRIEF DESCRIPTION OF THE DRAWINGS They are an external appearance schematic diagram (a) of the charging roll for electrophotographic apparatuses which concerns on one Embodiment of this invention, and its AA sectional drawing (b). 図１に示す電子写真機器用帯電ロールの表面近傍の拡大模式図である。FIG. 2 is an enlarged schematic view of the vicinity of the surface of the charging roll for an electrophotographic apparatus shown in FIG.
　本発明に係る電子写真機器用帯電ロール（以下、単に帯電ロールということがある。）について詳細に説明する。図１は、本発明の一実施形態に係る電子写真機器用帯電ロールの外観模式図（ａ）と、そのＡ－Ａ線断面図（ｂ）である。図２は、図１に示す電子写真機器用帯電ロールの表面近傍の拡大模式図である。 The charging roll for an electrophotographic apparatus (hereinafter, may be simply referred to as charging roll) according to the present invention will be described in detail. FIG. 1 is a schematic view showing an appearance (a) of the charging roll for an electrophotographic apparatus according to an embodiment of the present invention, and a cross-sectional view along the line AA thereof (b). FIG. 2 is an enlarged schematic view of the vicinity of the surface of the charging roll for an electrophotographic apparatus shown in FIG.
　帯電ロール１０は、軸体１２と、軸体１２の外周に形成された弾性体層１４と、弾性体層１４の外周に形成された表層１６と、を備える。弾性体層１４は、帯電ロール１０のベースとなる層である。表層１６は、帯電ロール１０の表面に現れる層となっている。 The charging roll 10 includes a shaft 12, an elastic layer 14 formed on the outer periphery of the shaft 12, and a surface layer 16 formed on the outer periphery of the elastic layer 14. The elastic layer 14 is a layer to be a base of the charging roll 10. The surface layer 16 is a layer appearing on the surface of the charging roll 10.
　表層１６は、バインダー樹脂２２と、大径粒子１８と、小径粒子２０と、を含有する。大径粒子１８および小径粒子２０により、表層１６の表面には凹凸が形成されている。大径粒子１８が存在する部分は比較的大きい凸部であり、小径粒子２０が存在する部分は比較的小さい凸部である。比較的小さい凸部は、比較的大きい凸部と比較的大きい凸部との間に１または２以上配置されている。大径粒子１８が存在する比較的大きい凸部が感光ドラムに接触する部分であり、小径粒子２０が存在する比較的小さい凸部は感光ドラムに接触しない部分である。大径粒子１８と小径粒子２０の形状は、特に限定されるものではないが、球状、真球状などが好ましい。 The surface layer 16 contains a binder resin 22, large diameter particles 18 and small diameter particles 20. Irregularities are formed on the surface of the surface layer 16 by the large diameter particles 18 and the small diameter particles 20. The portion where the large diameter particles 18 are present is a relatively large convex portion, and the portion where the small diameter particles 20 are present is a relatively small convex portion. The relatively small convex portion is disposed one or more or more between the relatively large convex portion and the relatively large convex portion. A relatively large convex portion in which the large diameter particles 18 are present is a portion in contact with the photosensitive drum, and a relatively small convex portion in which the small diameter particles 20 are present is a portion not in contact with the photosensitive drum. The shapes of the large diameter particles 18 and the small diameter particles 20 are not particularly limited, but spherical shapes, spherical shapes and the like are preferable.
　大径粒子１８は、平均粒子径１５μｍ以上５０μｍ以下の粒子である。このような大径粒子１８を含むことにより、表層１６の表面凹凸が十分に大きくなり、表層１６は感光ドラムとの間のギャップを十分に確保することができる。これにより、放電性能が向上するため、高い帯電性を確保することができる。大径粒子１８の平均粒子径が１５μｍ未満であると、表層１６は感光ドラムとの間のギャップを十分に確保することができず、高い帯電性を確保することができない。また、大径粒子１８の平均粒子径が５０μｍ超であると、帯電の均一性を満足することができない。大径粒子１８の平均粒子径は、感光ドラムとの間のギャップを大きくすることができるなどの観点から、より好ましくは２０μｍ以上、さらに好ましくは２５μｍ以上である。また、大径粒子１８の平均粒子径は、帯電の均一性を高めやすいなどの観点から、より好ましくは４５μｍ以下、さらに好ましくは４０μｍ以下である。大径粒子１８の平均粒子径は、レーザー回折・散乱式粒子径分布測定装置により測定されるメジアン径である。 The large diameter particles 18 are particles having an average particle diameter of 15 μm to 50 μm. By including such large-diameter particles 18, the surface irregularities of the surface layer 16 become sufficiently large, and the surface layer 16 can sufficiently secure a gap with the photosensitive drum. As a result, the discharge performance is improved, and high chargeability can be ensured. When the average particle diameter of the large-diameter particles 18 is less than 15 μm, the surface layer 16 can not sufficiently secure a gap with the photosensitive drum, and high chargeability can not be secured. In addition, when the average particle diameter of the large-diameter particles 18 is more than 50 μm, the charging uniformity can not be satisfied. The average particle diameter of the large-diameter particles 18 is more preferably 20 μm or more, and further preferably 25 μm or more from the viewpoint that the gap between the large-diameter particles 18 and the photosensitive drum can be increased. The average particle diameter of the large-diameter particles 18 is more preferably 45 μm or less, and still more preferably 40 μm or less, from the viewpoint of easily increasing the uniformity of charging. The average particle diameter of the large diameter particles 18 is a median diameter measured by a laser diffraction / scattering particle diameter distribution measuring apparatus.
　大径粒子１８は、特に限定されるものではないが、感光ドラムとの接触部における柔軟性を確保しやすいなどの観点から、樹脂粒子が好ましい。樹脂粒子としては、アクリル粒子、ウレタン粒子、ポリアミド粒子などが挙げられる。大径粒子１８は、これらのうちの１種の樹脂粒子で構成されていてもよいし、２種以上の樹脂粒子で構成されていてもよい。これらのうちでは、低変形率による低ヘタリ性などの観点から、アクリル粒子が好ましい。また、抵抗への影響度が小さいなどの観点から、ポリアミド粒子（ナイロン粒子）が好ましい。 The large diameter particles 18 are not particularly limited, but resin particles are preferable from the viewpoint of easily securing the flexibility at the contact portion with the photosensitive drum. As resin particles, acrylic particles, urethane particles, polyamide particles and the like can be mentioned. The large diameter particles 18 may be composed of one of these resin particles, or may be composed of two or more kinds of resin particles. Among these, acrylic particles are preferable from the viewpoint of low fixation and the like due to a low deformation rate. In addition, polyamide particles (nylon particles) are preferable from the viewpoint that the degree of influence on resistance is small.
　大径粒子１８は、感光ドラムとの間のギャップを維持しやすいなどの観点から、荷重に対する変形量が小さいことが好ましい。例えば、５０ｍＮの荷重がかかったときにその変形量が８０％以下であることが好ましい。より好ましくは７０％以下、さらに好ましくは６０％以下である。一方、柔軟性を確保するなどの観点から、その変形量は１０％以上であることが好ましい。より好ましくは２０％以上である。 The large-diameter particles 18 preferably have a small amount of deformation with respect to load, from the viewpoint of easily maintaining the gap between the large-diameter particles 18 and the photosensitive drum. For example, when a load of 50 mN is applied, the deformation amount is preferably 80% or less. More preferably, it is 70% or less, more preferably 60% or less. On the other hand, it is preferable that the amount of deformation is 10% or more from the viewpoint of securing flexibility and the like. More preferably, it is 20% or more.
　大径粒子１８の含有量は、特に限定されるものではないが、大径粒子１８の粒子間距離を適度に確保しやすい、帯電の均一性を高めやすいなどの観点から、バインダー樹脂２２の１００質量部に対し、５～４０質量部の範囲内であることが好ましい。より好ましくは５～３５質量部の範囲内、さら好ましくは１０～３０質量部の範囲内である。 The content of the large diameter particles 18 is not particularly limited, but from the viewpoint of appropriately securing the interparticle distance of the large diameter particles 18 and easily enhancing the uniformity of charging, 100 of the binder resin 22 It is preferably in the range of 5 to 40 parts by mass with respect to the parts by mass. More preferably, it is in the range of 5 to 35 parts by mass, more preferably in the range of 10 to 30 parts by mass.
　大径粒子１８間の平均距離は、６０μｍ以上であることが好ましい。大径粒子１８の量が適度となり、帯電の均一性を高めやすい。また、この観点から、大径粒子１８間の平均距離は、より好ましくは８０μｍ以上、さらに好ましくは１００μｍ以上である。また、大径粒子１８の量が適度となり、帯電の均一性を高めやすいなどの観点から、大径粒子１８間の平均距離は、３００μｍ以下であることが好ましい。より好ましくは２５０μｍ以下、さらに好ましくは２００μｍ以下である。大径粒子１８間の平均距離は、表層１６の表面写真を撮影し、任意の５箇所においてそれぞれ大径粒子１８間の距離を３つ測定し、合計１５点の平均により表す。大径粒子１８間の距離は、互いに向かい合う外周間距離で表す。 The average distance between the large diameter particles 18 is preferably 60 μm or more. The amount of the large diameter particles 18 is appropriate, and the uniformity of the charge can be easily improved. Moreover, from this viewpoint, the average distance between the large diameter particles 18 is more preferably 80 μm or more, and further preferably 100 μm or more. In addition, the average distance between the large diameter particles 18 is preferably 300 μm or less from the viewpoint that the amount of the large diameter particles 18 becomes appropriate and the uniformity of charging can be easily improved. More preferably, it is 250 micrometers or less, More preferably, it is 200 micrometers or less. The average distance between the large diameter particles 18 is obtained by taking a surface photograph of the surface layer 16 and measuring three distances between the large diameter particles 18 at any five points, and is represented by an average of 15 points in total. The distance between the large diameter particles 18 is represented by the distance between the outer circumferences facing each other.
　感光体との間のギャップを均一に維持しやすいなどの観点から、大径粒子１８と大径粒子１８は凝集体を形成しないで存在することが好ましい。 It is preferable that the large diameter particles 18 and the large diameter particles 18 be present without forming an aggregate from the viewpoint of easily maintaining the gap between the photosensitive member and the like uniformly.
　小径粒子２０は、平均粒子径３μｍ以上１５μｍ未満の粒子である。小径粒子２０が存在する部分の凸部は放電の起点となる。小径粒子２０を含むことにより、表層１６は放電の起点を確保し、小径粒子２０が分散することで帯電の均一性を満足することができる。小径粒子２０の平均粒子径が３μｍ未満であると、小径粒子２０が存在する部分の凸部が小さすぎて放電の起点となりにくく、帯電の均一性を満足することができない。また、小径粒子２０の平均粒子径が１５μｍ超であると、小径粒子２０が存在する部分の凸部が大きすぎて放電の起点となりにくく、帯電の均一性を満足することができない。小径粒子２０の平均粒子径は、帯電の均一性を向上させるなどの観点から、より好ましくは４μｍ以上、さらに好ましくは５μｍ以上である。また、より好ましくは１０μｍ以下、さらに好ましくは７μｍ以下である。小径粒子２０の平均粒子径は、レーザー回折・散乱式粒子径分布測定装置により測定されるメジアン径である。 The small diameter particles 20 are particles having an average particle diameter of 3 μm or more and less than 15 μm. The convex part of the part in which the small diameter particle 20 exists becomes an origin of discharge. By including the small diameter particles 20, the surface layer 16 secures the starting point of the discharge, and the uniformity of the charging can be satisfied by the small diameter particles 20 being dispersed. If the average particle diameter of the small-diameter particles 20 is less than 3 μm, the convex portion in the portion where the small-diameter particles 20 are present is too small to be a starting point of the discharge, and charging uniformity can not be satisfied. In addition, when the average particle diameter of the small diameter particles 20 is more than 15 μm, the convex portion of the portion where the small diameter particles 20 are present is too large to be a starting point of the discharge, and charging uniformity can not be satisfied. The average particle diameter of the small-diameter particles 20 is more preferably 4 μm or more, and further preferably 5 μm or more from the viewpoint of improving the uniformity of charging. Moreover, More preferably, it is 10 micrometers or less, More preferably, it is 7 micrometers or less. The average particle diameter of the small diameter particles 20 is a median diameter measured by a laser diffraction / scattering particle diameter distribution measuring apparatus.
　小径粒子２０は、感光ドラムとの非接触部に配置されることから、柔軟性に優れる樹脂粒子であってもよいし、比較的硬い無機粒子であってもよい。これらのうちでは、大径粒子１８との硬度差を大きくして耐久時の汚れを低減しやすいなどの観点から、比較的硬い無機粒子が好ましい。無機粒子のうちでは、耐久時の汚れが一層低減するなどの観点から、シリカ粒子が特に好ましい。 The small-diameter particles 20 may be resin particles excellent in flexibility or relatively hard inorganic particles because they are disposed in the non-contact portion with the photosensitive drum. Among these, relatively hard inorganic particles are preferable from the viewpoint of, for example, increasing the difference in hardness with the large-diameter particles 18 to easily reduce stains during durability. Among the inorganic particles, silica particles are particularly preferable from the viewpoint of further reducing contamination during durability.
　小径粒子２０の含有量は、バインダー樹脂２２の１００質量部に対し、５～５０質量部の範囲内である。小径粒子２０の含有量が５質量部未満であると、放電の起点が少なく帯電の均一性が確保できない。小径粒子２０の含有量が５０質量部超であると、小径粒子２０が多すぎて小径粒子２０を含む粒子の凝集が抑えられず、小径粒子２０を含む粒子の凝集体が大きくなりすぎて帯電の均一性が確保できない。小径粒子２０の含有量は、上記観点から、バインダー樹脂２２の１００質量部に対し、より好ましくは１０質量部以上、さらに好ましくは１５質量部以上である。また、上記観点から、バインダー樹脂２２の１００質量部に対し、より好ましくは４０質量部以下、さらに好ましくは３０質量部以下である。 The content of the small diameter particles 20 is in the range of 5 to 50 parts by mass with respect to 100 parts by mass of the binder resin 22. If the content of the small-diameter particles 20 is less than 5 parts by mass, the starting point of the discharge is small, and the uniformity of charging can not be ensured. When the content of the small diameter particles 20 is more than 50 parts by mass, the small diameter particles 20 are too large to suppress aggregation of the particles including the small diameter particles 20, and the aggregates of the particles including the small diameter particles 20 become too large to be charged. Uniformity can not be ensured. The content of the small diameter particles 20 is more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, with respect to 100 parts by mass of the binder resin 22 from the above viewpoint. Further, from the above viewpoint, the amount is more preferably 40 parts by mass or less, still more preferably 30 parts by mass or less with respect to 100 parts by mass of the binder resin 22.
　小径粒子２０間の平均距離は、４０μｍ以下であることが好ましい。小径粒子２０間の平均距離が小さいほど、帯電の均一性を高めやすい。この観点から、小径粒子２０間の平均距離は、より好ましくは３０μｍ以下、さらに好ましくは２０μｍ以下である。小径粒子２０間の平均距離は、表層１６の表面写真を撮影し、任意の５箇所においてそれぞれ小径粒子２０間の距離を３つ測定し、合計１５点の平均により表す。小径粒子２０間の距離は、互いに向かい合う外周間距離で表す。 The average distance between the small diameter particles 20 is preferably 40 μm or less. The smaller the average distance between the small diameter particles 20, the easier it is to improve the uniformity of charging. From this viewpoint, the average distance between the small diameter particles 20 is more preferably 30 μm or less, still more preferably 20 μm or less. The average distance between the small-diameter particles 20 is obtained by taking a surface photograph of the surface layer 16 and measuring three distances between the small-diameter particles 20 at any five points, and is represented by an average of a total of 15 points. The distance between the small diameter particles 20 is represented by the distance between the outer circumferences facing each other.
　表層１６においては、図２（ａ）に示すように、小径粒子２０を含む粒子の凝集体がないことでもよいが、図２（ｂ）に示すように、小径粒子２０を含む粒子の凝集体を有していてもよい。小径粒子２０を含む粒子の凝集体としては、小径粒子２０と大径粒子１８の両方を含む粒子の凝集体や、小径粒子２０のみからなる粒子の凝集体がある。例えば図２（ｂ）には、小径粒子２０の２つと大径粒子１８の１つからなる粒子の凝集体２４ａ、小径粒子２０の２つからなる粒子の凝集体２４ｂ、小径粒子２０の１つと大径粒子１８の１つからなる粒子の凝集体２４ｃのそれぞれを示している。小径粒子２０と大径粒子１８の両方を含む粒子の凝集体があると、小径粒子２０同士の凝集や大径粒子１８同士の凝集を抑えて小径粒子２０および大径粒子１８を適度に分散させやすい。小径粒子２０のみからなる粒子の凝集体があると、放電制御の点で好ましい。 In the surface layer 16, as shown in FIG. 2 (a), there may be no aggregates of particles including the small diameter particles 20, but as shown in FIG. 2 (b), aggregates of particles including the small diameter particles 20. May be included. As an aggregate of particles including the small diameter particles 20, there are an aggregate of particles including both the small diameter particles 20 and the large diameter particles 18, and an aggregate of particles consisting of only the small diameter particles 20. For example, in FIG. 2 (b), an aggregate 24a of particles consisting of two small diameter particles 20 and one large diameter particle 18, an aggregate 24b of particles consisting of two small diameter particles 20, and one of the small diameter particles 20 Each of the aggregate 24c of the particle which consists of one of the large diameter particle 18 is shown. When there is an aggregate of particles including both the small diameter particles 20 and the large diameter particles 18, the aggregation of the small diameter particles 20 and the aggregation of the large diameter particles 18 are suppressed to appropriately disperse the small diameter particles 20 and the large diameter particles 18 Cheap. It is preferable in terms of discharge control that there is an aggregate of particles consisting of only the small diameter particles 20.
　小径粒子２０を含む粒子の凝集体の大きさは、６μｍ以上５０μｍ以下である。粒子の分散性に優れるため、帯電の均一性を満足することができる。凝集体の大きさが５０μｍ超であると、粒子の分散性が悪く、帯電の均一性を満足することができない。また、この観点から、凝集体の大きさは、好ましくは４５μｍ以下、さらに好ましくは４０μｍ以下である。小径粒子２０を含む粒子の凝集体は、弾性体層１４の表面に沿った面内に集まる粒子の集合体であり、バインダー樹脂２２の量や厚みなどから、厚さ方向への積み重なりは少ない。小径粒子２０を含む粒子の凝集体の大きさは、表層１６の表面写真を撮影し、任意の５箇所においてそれぞれ小径粒子２０を含む粒子の凝集体の最大距離を３つ測定し、合計１５点の平均により表す。 The size of the aggregate of particles including the small diameter particles 20 is 6 μm or more and 50 μm or less. Since the dispersibility of the particles is excellent, the uniformity of charging can be satisfied. If the size of the aggregate is more than 50 μm, the dispersibility of the particles is poor, and the uniformity of charging can not be satisfied. Further, from this viewpoint, the size of the aggregate is preferably 45 μm or less, more preferably 40 μm or less. The aggregate of particles including the small diameter particles 20 is an aggregate of particles collected in a plane along the surface of the elastic layer 14, and there is little stacking in the thickness direction due to the amount and thickness of the binder resin 22 and the like. The size of the aggregate of particles including the small diameter particles 20 is a photograph of the surface of the surface layer 16 and the maximum distance of three aggregates of the particles including the small diameter particles 20 is measured at any five points, and a total of 15 points Expressed by the average of
　大径粒子１８と小径粒子２０の平均粒子径の差は、１０μｍ以上であることが好ましい。平均粒子径の差が大きいほど、表層１６の表面凹凸が大きくなり、表層１６は感光ドラムとの間のギャップを確保しやすい。この観点から、平均粒子径の差は、より好ましくは１５μｍ以上、さらに好ましくは２０μｍ以上である。 The difference in average particle size between the large diameter particles 18 and the small diameter particles 20 is preferably 10 μm or more. As the difference in average particle size is larger, the surface unevenness of the surface layer 16 becomes larger, and the surface layer 16 can easily secure a gap with the photosensitive drum. From this viewpoint, the difference in average particle size is more preferably 15 μm or more, and further preferably 20 μm or more.
　大径粒子１８の硬度は、小径粒子２０の硬度よりも小さいことが好ましい。硬度差が大きいほど、耐久時の汚れを低減しやすい。この観点から、大径粒子１８の硬度ａと小径粒子２０の硬度ｂの関係は、ａ／ｂ＜１であることが好ましい。より好ましくはａ／ｂ≦０．７、さらに好ましくはａ／ｂ≦０．６、特に好ましくはａ／ｂ≦０．５である。 The hardness of the large diameter particles 18 is preferably smaller than the hardness of the small diameter particles 20. The larger the hardness difference, the easier it is to reduce the stain during endurance. From this viewpoint, the relationship between the hardness a of the large diameter particles 18 and the hardness b of the small diameter particles 20 is preferably a / b <1. More preferably, a / b ≦ 0.7, still more preferably a / b ≦ 0.6, and particularly preferably a / b ≦ 0.5.
　表層１６において、大径粒子１８が存在する部分における凸部の高さは、１０μｍ以上であることが好ましい。より好ましくは１５μｍ以上、さらに好ましくは２０μｍ以上である。この凸部の高さが１０μｍ以上であると、感光ドラムとの間のギャップを確保しやすい。また、小径粒子２０が存在する部分における凸部の高さは、２．０μｍ以上であることが好ましい。より好ましくは２．５μｍ以上、さらに好ましくは３．０μｍ以上である。この凸部の高さが２．０μｍ以上であると、放電の起点を確保しやすい。凸部の高さは、粒子が存在していない部分（例えば小径粒子２０と小径粒子２０の間の部分など）における表層１６の表面からの高さで表される。凸部の高さは、レーザー顕微鏡（例えばキーエンス製、「ＶＫ－９５１０」など）を用いて断面を観察することにより測定することができる。例えば任意の位置の５か所について凸部の高さをそれぞれ測定し、その平均によって表すことができる。 In the surface layer 16, it is preferable that the height of the convex part in the part in which the large diameter particle 18 exists is 10 micrometers or more. More preferably, it is 15 micrometers or more, More preferably, it is 20 micrometers or more. When the height of the convex portion is 10 μm or more, it is easy to secure a gap between the convex portion and the photosensitive drum. Moreover, it is preferable that the height of the convex part in the part in which the small diameter particle 20 exists is 2.0 micrometers or more. More preferably, it is 2.5 micrometers or more, More preferably, it is 3.0 micrometers or more. It is easy to ensure the starting point of discharge as the height of this convex part is 2.0 micrometers or more. The height of the convex portion is represented by the height from the surface of the surface layer 16 in a portion where no particle is present (for example, a portion between the small particle 20 and the small particle 20). The height of the convex portion can be measured by observing the cross section using a laser microscope (for example, “VK-9510” manufactured by Keyence Corporation). For example, the heights of the projections can be measured at five positions at arbitrary positions, and the heights can be represented by the average thereof.
　バインダー樹脂２２は、特に限定されるものではなく、要求特性などに応じて好適な材料を選択すればよい。バインダーとしては、アクリル系樹脂、メタクリル系樹脂、フッ素系樹脂、シリコーン系樹脂、ポリカーボネート系樹脂、ウレタン系樹脂、ポリアミド系樹脂などが挙げられる。これらは、表層１６のバインダー樹脂２２として１種単独で用いてもよいし、２種以上組み合わせて用いてもよい。これらのうちでは、抵抗制御・柔軟性などの観点から、ポリアミド系樹脂、アクリル系樹脂がより好ましい。また、バインダー樹脂２２は、粒子との密着性などの観点から、粒子と同じ材質のものが好ましい。 The binder resin 22 is not particularly limited, and a suitable material may be selected according to the required characteristics and the like. Examples of the binder include acrylic resins, methacrylic resins, fluorine resins, silicone resins, polycarbonate resins, urethane resins, and polyamide resins. These may be used singly as the binder resin 22 of the surface layer 16 or may be used in combination of two or more. Among these, polyamide resins and acrylic resins are more preferable from the viewpoint of resistance control, flexibility and the like. The binder resin 22 is preferably made of the same material as that of the particles from the viewpoint of adhesion to the particles and the like.
　表層１６は、バインダー樹脂２２、大径粒子１８、小径粒子２０に加えて、有機酸を含んでいてもよい。表層形成用組成物中では有機酸はイオン化する。イオン化した有機酸が粒子の周りに存在することで有機酸が持つ負電荷を粒子に持たせることができる。表面積のより大きい大径粒子１８は小径粒子２０よりも多くの負電荷を持つため、大径粒子１８同士は静電反発を起こしやすい。このために、表層１６がさらに有機酸を含有すると、大径粒子１８同士の凝集を抑える効果により優れるものと推察される。一方、小径粒子２０は、大径粒子１８に比べ負電荷が小さいため、大径粒子１８と小径粒子２０の間の静電反発は小さく、ファンデルワールス力差によって大径粒子１８と小径粒子２０は凝集することができる。このために、表層１６がさらに有機酸を含有すると、効率良く大径粒子１８の周りに小径粒子２０を配置することができるものと推察される。また、小径粒子２０同士の間の静電反発により、大径粒子１８の周りに配される小径粒子２０の数は少なくなる。以上により、表層１６がさらに有機酸を含有すると、小径粒子２０を含む粒子の凝集体の大きさを小さく抑えることができる。 The surface layer 16 may contain an organic acid in addition to the binder resin 22, the large diameter particles 18, and the small diameter particles 20. The organic acid is ionized in the composition for surface layer formation. The presence of the ionized organic acid around the particles allows the particles to have a negative charge that the organic acid has. Since the large diameter particles 18 having a larger surface area have more negative charges than the small diameter particles 20, the large diameter particles 18 are likely to cause electrostatic repulsion. For this reason, when the surface layer 16 further contains an organic acid, it is surmised that the surface layer 16 is more excellent in the effect of suppressing the aggregation of the large diameter particles 18 with each other. On the other hand, since the small diameter particle 20 has a smaller negative charge than the large diameter particle 18, the electrostatic repulsion between the large diameter particle 18 and the small diameter particle 20 is small, and the large diameter particle 18 and the small diameter particle 20 are Can aggregate. For this reason, when the surface layer 16 further contains an organic acid, it is presumed that the small diameter particles 20 can be efficiently arranged around the large diameter particles 18. Further, the electrostatic repulsion between the small diameter particles 20 reduces the number of the small diameter particles 20 disposed around the large diameter particles 18. As described above, when the surface layer 16 further contains the organic acid, the size of the aggregate of particles including the small diameter particles 20 can be suppressed to a small size.
　有機酸としては、カルボン酸、スルホン酸などを挙げることができる。カルボン酸としては、クエン酸、シュウ酸、酢酸、ギ酸などを挙げることができる。これらは、表層１６に添加する有機酸として１種単独で用いてもよいし、２種以上を組み合わせて用いてもよい。これらのうちでは、カルボン酸が好ましく、また、クエン酸、シュウ酸などの水酸基を有する有機酸が特に好ましい。有機酸が水酸基を有する有機酸であると、表層１６の耐摩耗性、耐放電性、荷電性を向上することができる。有機酸の水酸基は、バインダー樹脂であるナイロンのアミド基やアクリル樹脂のカルボニル基などと水素結合しやすく、水素結合による相互作用によって表層１６の耐摩耗性、耐放電性が向上するためと推察される。また、有機酸の水酸基によって表層１６の静電容量が大きくなることで、荷電性が向上するためと推察される。 Examples of the organic acid include carboxylic acid and sulfonic acid. Examples of carboxylic acids include citric acid, oxalic acid, acetic acid, formic acid and the like. These may be used alone as an organic acid to be added to the surface layer 16 or may be used in combination of two or more. Among these, carboxylic acids are preferable, and organic acids having a hydroxyl group such as citric acid and oxalic acid are particularly preferable. When the organic acid is an organic acid having a hydroxyl group, the abrasion resistance, the discharge resistance and the chargeability of the surface layer 16 can be improved. The hydroxyl group of the organic acid is likely to form a hydrogen bond with the amide group of nylon as the binder resin, the carbonyl group of the acrylic resin, etc., and it is speculated that the abrasion resistance and discharge resistance of the surface layer 16 will be improved by the hydrogen bond interaction. Ru. Further, it is presumed that the chargeability is improved by the increase in the capacitance of the surface layer 16 due to the hydroxyl group of the organic acid.
　有機酸の含有量は、大径粒子１８同士の凝集を抑える効果に優れる、効率良く大径粒子１８の周りに小径粒子２０を配置する、小径粒子２０を含む粒子の凝集体の大きさを小さく抑えるなどの観点から、バインダー樹脂１００質量部に対し、０．１質量部以上であることが好ましい。より好ましくは０．５質量部以上である。また、有機酸の含有量は、表層形成用組成物における有機酸あるいは有機酸の希釈液の相溶性の観点から、バインダー樹脂１００質量部に対し、１０質量部以下であることが好ましい。より好ましくは７質量部以下である。 The content of the organic acid is excellent in the effect of suppressing the cohesion of the large diameter particles 18, efficiently arranges the small diameter particles 20 around the large diameter particles 18, and reduces the size of the aggregate of particles including the small diameter particles 20. It is preferable that it is 0.1 mass part or more with respect to 100 mass parts of binder resin from a viewpoint of suppressing. More preferably, it is 0.5 parts by mass or more. In addition, the content of the organic acid is preferably 10 parts by mass or less with respect to 100 parts by mass of the binder resin from the viewpoint of the compatibility of the organic acid or the diluted solution of the organic acid in the composition for surface layer formation. More preferably, it is 7 parts by mass or less.
　表層１６は、バインダー樹脂２２、大径粒子１８、小径粒子２０に加えて、添加剤を含んでいてもよいし、含んでいなくてもよい。添加剤としては、導電剤、安定剤、紫外線吸収剤、滑剤、離形剤、染料、顔料、難燃剤などが挙げられる。導電剤としては、イオン導電剤（第４級アンモニウム塩など）や電子導電剤（カーボンブラックなど）などが挙げられる。 The surface layer 16 may or may not contain an additive in addition to the binder resin 22, the large diameter particles 18, and the small diameter particles 20. Examples of the additive include a conductive agent, a stabilizer, an ultraviolet light absorber, a lubricant, a release agent, a dye, a pigment, a flame retardant and the like. Examples of the conductive agent include ion conductive agents (quaternary ammonium salts and the like) and electron conductive agents (carbon black and the like).
　表層１６は、材料種、導電剤の配合などにより、所定の体積抵抗率に調整することができる。表層１６の体積抵抗率は、用途などに応じて１０５～１０１１Ω・ｃｍ、１０８～１０１０Ω・ｃｍの範囲などに適宜設定すればよい。 The surface layer 16 can be adjusted to a predetermined volume resistivity by the type of material, the composition of the conductive agent, and the like. The volume resistivity of the surface layer 16 may be appropriately set in the range of 10 5 to 10 11 Ω · cm, 10 8 to 10 10 Ω · cm, or the like depending on the application and the like.
　表層１６の厚みは、粒子が存在していない部分（例えば小径粒子２０と小径粒子２０の間の部分など）における厚みで表される。表層１６の厚みは、大径粒子１８や小径粒子２０を表層中に十分に固定しやすいなどの観点から、１．０μｍ以上であることが好ましい。より好ましくは１．５μｍ以上である。一方、小径粒子２０が存在する部分における凸部の大きさを確保して放電の起点を確保しやすいなどの観点から、３．０μｍ以下であることが好ましい。より好ましくは２．５μｍ以下である。表層１６の厚みは、レーザー顕微鏡（例えばキーエンス製、「ＶＫ－９５１０」など）を用いて断面を観察することにより測定することができる。例えば任意の位置の５か所について、弾性体層１４の表面から表層１６の表面までの距離をそれぞれ測定し、その平均によって表すことができる。 The thickness of the surface layer 16 is represented by the thickness in the part where particles do not exist (for example, the part between the small diameter particles 20 and the small diameter particles 20). The thickness of the surface layer 16 is preferably 1.0 μm or more from the viewpoint of easily fixing the large-diameter particles 18 and the small-diameter particles 20 in the surface layer. More preferably, it is 1.5 μm or more. On the other hand, the diameter is preferably 3.0 μm or less from the viewpoint of securing the size of the convex portion in the portion where the small diameter particles 20 are present and easily securing the starting point of the discharge. More preferably, it is 2.5 μm or less. The thickness of the surface layer 16 can be measured by observing the cross section using a laser microscope (for example, "VK-9510" manufactured by Keyence Corporation). For example, the distance from the surface of the elastic layer 14 to the surface of the surface layer 16 can be measured at five positions in any position, and can be represented by the average.
　表層１６は、バインダー樹脂２２、大径粒子１８、小径粒子２０を含む表層形成用組成物を用い、これを弾性体層１４の外周面に塗工し、乾燥処理などを適宜行うことにより形成することができる。表層形成用組成物において、バインダー樹脂２２、大径粒子１８、小径粒子２０は、分散媒を用いて分散液として調製することができる。分散媒としては、メチルエチルケトン（ＭＥＫ），メチルイソブチルケトンなどのケトン系溶媒、イソプロピルアルコール（ＩＰＡ），メタノール，エタノールなどのアルコール系溶媒、ヘキサン，トルエンなどの炭化水素系溶媒、酢酸エチル，酢酸ブチルなどの酢酸系溶媒、ジエチルエーテル，テトラヒドロフラン等のエーテル系溶媒、水などが挙げられる。 The surface layer 16 is formed by applying the composition for forming a surface layer including the binder resin 22, the large diameter particles 18, and the small diameter particles 20 to the outer peripheral surface of the elastic layer 14 and performing drying treatment etc. as appropriate. be able to. In the composition for forming a surface layer, the binder resin 22, the large diameter particles 18, and the small diameter particles 20 can be prepared as a dispersion using a dispersion medium. As the dispersion medium, ketone solvents such as methyl ethyl ketone (MEK) and methyl isobutyl ketone, alcohol solvents such as isopropyl alcohol (IPA), methanol and ethanol, hydrocarbon solvents such as hexane and toluene, ethyl acetate, butyl acetate and the like Acetic acid solvents of the above, ether solvents such as diethyl ether and tetrahydrofuran, water and the like.
　表層形成用組成物は、塗工前に粒子を十分に分散させることが好ましい。例えば表層形成用組成物に対し超音波を照射することで、塗工前に粒子を十分に分散させることができる。また、有機酸を含む表層形成用組成物は、その静電相互作用によって塗工前に粒子を十分に分散させることができる。有機酸を含む表層形成用組成物は、超音波を照射する工程を削減あるいは低減することができる。 It is preferable that the composition for surface layer formation fully disperses particles before coating. For example, the particles can be sufficiently dispersed before coating by irradiating the composition for forming a surface layer with ultrasonic waves. Moreover, the composition for surface layer formation containing an organic acid can fully disperse | distribute particle | grains before coating by the electrostatic interaction. The composition for surface layer formation containing an organic acid can reduce or reduce the process of irradiating ultrasonic waves.
　弾性体層１４は、架橋ゴムを含有する。弾性体層１４は、未架橋ゴムを含有する導電性ゴム組成物により形成される。架橋ゴムは、未架橋ゴムを架橋することにより得られる。未架橋ゴムは、極性ゴムであってもよいし、非極性ゴムであってもよい。導電性に優れるなどの観点から、未架橋ゴムは極性ゴムがより好ましい。 The elastic layer 14 contains a crosslinked rubber. The elastic layer 14 is formed of a conductive rubber composition containing uncrosslinked rubber. Crosslinked rubber is obtained by crosslinking uncrosslinked rubber. The uncrosslinked rubber may be a polar rubber or a nonpolar rubber. From the viewpoint of excellent conductivity etc., the non-crosslinked rubber is more preferably a polar rubber.
　極性ゴムは、極性基を有するゴムであり、極性基としては、クロロ基、ニトリル基、カルボキシル基、エポキシ基などを挙げることができる。極性ゴムとしては、具体的には、ヒドリンゴム、ニトリルゴム（ＮＢＲ）、ウレタンゴム（Ｕ）、アクリルゴム（アクリル酸エステルと２－クロロエチルビニルエーテルとの共重合体、ＡＣＭ）、クロロプレンゴム（ＣＲ）、エポキシ化天然ゴム（ＥＮＲ）などを挙げることができる。極性ゴムのうちでは、体積抵抗率が特に低くなりやすいなどの観点から、ヒドリンゴム、ニトリルゴム（ＮＢＲ）がより好ましい。 The polar rubber is a rubber having a polar group, and examples of the polar group include chloro group, nitrile group, carboxyl group and epoxy group. Specific examples of polar rubbers include hydrin rubber, nitrile rubber (NBR), urethane rubber (U), acrylic rubber (copolymer of acrylic ester and 2-chloroethyl vinyl ether, ACM), chloroprene rubber (CR) And epoxidized natural rubber (ENR). Among polar rubbers, a hydrin rubber and a nitrile rubber (NBR) are more preferable from the viewpoint that the volume resistivity tends to be particularly low.
　ヒドリンゴムとしては、エピクロルヒドリンの単独重合体（ＣＯ）、エピクロルヒドリン－エチレンオキサイド二元共重合体（ＥＣＯ）、エピクロルヒドリン－アリルグリシジルエーテル二元共重合体（ＧＣＯ）、エピクロルヒドリン－エチレンオキサイド－アリルグリシジルエーテル三元共重合体（ＧＥＣＯ）などを挙げることができる。 Examples of hydrin rubbers include epichlorohydrin homopolymer (CO), epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-allyl glycidyl ether binary copolymer (GCO), epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary A copolymer (GECO) etc. can be mentioned.
　ウレタンゴムとしては、分子内にエーテル結合を有するポリエーテル型のウレタンゴムを挙げることができる。ポリエーテル型のウレタンゴムは、両末端にヒドロキシル基を有するポリエーテルとジイソシアネートとの反応により製造できる。ポリエーテルとしては、特に限定されるものではないが、ポリエチレングリコール、ポリプロピレングリコールなどを挙げることができる。ジイソシアネートとしては、特に限定されるものではないが、トリレンジイソシアネート、ジフェニルメタンジイソシアネートなどを挙げることができる。 As a urethane rubber, the polyether-type urethane rubber which has an ether bond in a molecule | numerator can be mentioned. The polyether type urethane rubber can be produced by the reaction of a polyether having a hydroxyl group at both ends with a diisocyanate. The polyether is not particularly limited, and polyethylene glycol, polypropylene glycol and the like can be mentioned. Although it does not specifically limit as diisocyanate, Tolylene diisocyanate, diphenylmethane diisocyanate etc. can be mentioned.
　非極性ゴムとしては、イソプレンゴム（ＩＲ）、天然ゴム（ＮＲ）、スチレンブタジエンゴム（ＳＢＲ）、ブタジエンゴム（ＢＲ）などが挙げられる。 Examples of nonpolar rubbers include isoprene rubber (IR), natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR) and the like.
　架橋剤としては、硫黄架橋剤、過酸化物架橋剤、脱塩素架橋剤を挙げることができる。これらの架橋剤は、単独で用いても良いし、２種以上組み合わせて用いても良い。 As a crosslinking agent, a sulfur crosslinking agent, a peroxide crosslinking agent, and a dechlorination crosslinking agent can be mentioned. These crosslinking agents may be used alone or in combination of two or more.
　硫黄架橋剤としては、粉末硫黄、沈降硫黄、コロイド硫黄、表面処理硫黄、不溶性硫黄、塩化硫黄、チウラム系加硫促進剤、高分子多硫化物などの従来より公知の硫黄架橋剤を挙げることができる。 Examples of sulfur crosslinking agents include conventionally known sulfur crosslinking agents such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, sulfur chloride, thiuram vulcanization accelerator, and polymeric polysulfides. it can.
　過酸化物架橋剤としては、パーオキシケタール、ジアルキルパーオキサイド、パーオキシエステル、ケトンパーオキサイド、パーオキシジカーボネート、ジアシルパーオキサイド、ハイドロパーオキサイドなどの従来より公知の過酸化物架橋剤を挙げることができる。 Examples of peroxide crosslinking agents include conventionally known peroxide crosslinking agents such as peroxy ketals, dialkyl peroxides, peroxy esters, ketone peroxides, peroxy dicarbonates, diacyl peroxides and hydroperoxides. Can.
　脱塩素架橋剤としては、ジチオカーボネート化合物を挙げることができる。より具体的には、キノキサリン－２，３－ジチオカーボネート、６－メチルキノキサリン－２，３－ジチオカーボネート、６－イソプロピルキノキサリン－２，３－ジチオカーボネート、５，８－ジメチルキノキサリン－２，３－ジチオカーボネートなどを挙げることができる。 As a dechlorination crosslinking agent, a dithiocarbonate compound can be mentioned. More specifically, quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-dithiocarbonate, 6-isopropylquinoxaline-2,3-dithiocarbonate, 5,8-dimethylquinoxaline-2,3- A dithio carbonate etc. can be mentioned.
　架橋剤の配合量としては、ブリードしにくいなどの観点から、未架橋ゴム１００質量部に対して、好ましくは０．１～２質量部の範囲内、より好ましくは０．３～１．８質量部の範囲内、さらに好ましくは０．５～１．５質量部の範囲内である。 The compounding amount of the crosslinking agent is preferably in the range of 0.1 to 2 parts by mass, more preferably 0.3 to 1.8 parts by mass with respect to 100 parts by mass of the non-crosslinked rubber from the viewpoint of hardly bleeding or the like. Within the range of part, more preferably within the range of 0.5 to 1.5 parts by mass.
　架橋剤として脱塩素架橋剤を用いる場合には、脱塩素架橋促進剤を併用しても良い。脱塩素架橋促進剤としては、１，８－ジアザビシクロ（５，４，０）ウンデセン－７（以下、ＤＢＵと略称する。）もしくはその弱酸塩を挙げることができる。脱塩素架橋促進剤は、ＤＢＵの形態として用いても良いが、その取り扱い面から、その弱酸塩の形態として用いることが好ましい。ＤＢＵの弱酸塩としては、炭酸塩、ステアリン酸塩、２－エチルヘキシル酸塩、安息香酸塩、サリチル酸塩、３－ヒドロキシ－２－ナフトエ酸塩、フェノール樹脂塩、２－メルカプトベンゾチアゾール塩、２－メルカプトベンズイミダゾール塩などを挙げることができる。 When a dechlorination crosslinking agent is used as the crosslinking agent, a dechlorination crosslinking accelerator may be used in combination. As a dechlorination crosslinking accelerator, 1,8-diazabicyclo (5,4,0) undecen-7 (hereinafter abbreviated as DBU) or a weak acid salt thereof can be mentioned. Although the dechlorination crosslinking accelerator may be used in the form of DBU, it is preferably used in the form of its weak acid salt from the viewpoint of its handling. As weak acid salts of DBU, carbonates, stearates, 2-ethylhexyl salts, benzoates, salicylates, 3-hydroxy-2-naphthoates, phenolic resin salts, 2-mercaptobenzothiazole salts, 2- Mercapto benzimidazole salts and the like can be mentioned.
　脱塩素架橋促進剤の含有量としては、ブリードしにくいなどの観点から、未架橋ゴム１００質量部に対して、０．１～２質量部の範囲内であることが好ましい。より好ましくは０．３～１．８質量部の範囲内、さらに好ましくは０．５～１．５質量部の範囲内である。 The content of the dechlorination crosslinking accelerator is preferably in the range of 0.1 to 2 parts by mass with respect to 100 parts by mass of the uncrosslinked rubber, from the viewpoint of hardly bleeding. More preferably, it is in the range of 0.3 to 1.8 parts by mass, still more preferably in the range of 0.5 to 1.5 parts by mass.
　弾性体層１４には、導電性付与のため、カーボンブラック、グラファイト、ｃ－ＴｉＯ２、ｃ－ＺｎＯ、ｃ－ＳｎＯ２（ｃ－は、導電性を意味する。）、イオン導電剤（４級アンモニウム塩、ホウ酸塩、界面活性剤など）などの従来より公知の導電剤を適宜添加することができる。また、必要に応じて、各種添加剤を適宜添加しても良い。添加剤としては、滑剤、加硫促進剤、老化防止剤、光安定剤、粘度調整剤、加工助剤、難燃剤、可塑剤、発泡剤、充填剤、分散剤、消泡剤、顔料、離型剤などを挙げることができる。 The elastic layer 14 is made of carbon black, graphite, c-TiO 2 , c-ZnO, c-SnO 2 (c-means conductivity), an ion conductive agent (quaternary) to impart conductivity. Conventionally known conductive agents such as ammonium salts, borates, surfactants and the like can be added as appropriate. In addition, various additives may be added as appropriate. As additives, lubricants, vulcanization accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, foaming agents, fillers, dispersants, antifoam agents, pigments, release agents Examples include molds and the like.
　弾性体層１４は、架橋ゴムの種類、イオン導電剤の配合量、電子導電剤の配合などにより、所定の体積抵抗率に調整することができる。弾性体層１４の体積抵抗率は、用途などに応じて１０２～１０１０Ω・ｃｍ、１０３～１０９Ω・ｃｍ、１０４～１０８Ω・ｃｍの範囲などに適宜設定すればよい。 The elastic layer 14 can be adjusted to a predetermined volume resistivity by the type of crosslinked rubber, the compounding amount of the ion conductive agent, the compounding of the electron conductive agent, and the like. The volume resistivity of the elastic layer 14 may be appropriately set in the range of 10 2 to 10 10 Ω · cm, 10 3 to 10 9 Ω · cm, 10 4 to 10 8 Ω · cm, etc. depending on the application etc. .
　弾性体層１４の厚みは、特に限定されるものではなく、用途などに応じて０．１～１０ｍｍの範囲内などで適宜設定すればよい。 The thickness of the elastic layer 14 is not particularly limited, and may be appropriately set in the range of 0.1 to 10 mm according to the application and the like.
　弾性体層１４は、例えば、次のようにして製造することができる。まず、軸体１２をロール成形金型の中空部に同軸的に設置し、未架橋の導電性ゴム組成物を注入して、加熱・硬化（架橋）させた後、脱型するか、あるいは、軸体１２の表面に未架橋の導電性ゴム組成物を押出成形するなどにより、軸体１２の外周に弾性体層１４を形成する。 The elastic layer 14 can be manufactured, for example, as follows. First, the shaft 12 is coaxially installed in the hollow portion of the roll forming mold, and the uncrosslinked conductive rubber composition is injected, heated and cured (crosslinked), and then removed or The elastic layer 14 is formed on the outer periphery of the shaft 12 by extruding an uncrosslinked conductive rubber composition on the surface of the shaft 12 or the like.
　軸体１２は、導電性を有するものであれば特に限定されない。具体的には、鉄、ステンレス、アルミニウムなどの金属製の中実体、中空体からなる芯金などを例示することができる。軸体１２の表面には、必要に応じて、接着剤、プライマーなどを塗布しても良い。つまり、弾性体層１４は、接着剤層（プライマー層）を介して軸体１２に接着されていてもよい。接着剤、プライマーなどには、必要に応じて導電化を行なっても良い。 The shaft 12 is not particularly limited as long as it has conductivity. Specifically, a solid body made of metal such as iron, stainless steel, or aluminum, a cored bar made of a hollow body, and the like can be exemplified. An adhesive, a primer or the like may be applied to the surface of the shaft 12 as necessary. That is, the elastic layer 14 may be bonded to the shaft 12 via the adhesive layer (primer layer). The adhesive, the primer, etc. may be made conductive as required.
　以上の構成の帯電ロール１０によれば、表層１６が、特定の大径粒子１８と特定の小径粒子２０とを含有し、小径粒子２０の含有量が特定量であり、小径粒子２０を含む粒子の凝集体の大きさが特定範囲とされていることから、感光ドラムとの間のギャップを十分に確保することができるとともに、放電の起点を均一に確保することができる。これにより、帯電性能を高くすることができるとともに帯電の均一性も満足することができる。 According to the charging roll 10 having the above configuration, the surface layer 16 contains the specific large-diameter particles 18 and the specific small-diameter particles 20, and the content of the small-diameter particles 20 is a specific amount. Since the size of the aggregate is within the specific range, the gap between the aggregate and the photosensitive drum can be sufficiently secured, and the discharge starting point can be uniformly secured. As a result, the charging performance can be enhanced and the uniformity of charging can be satisfied.
　本発明に係る帯電ロールの構成としては、図１に示す構成に限定されるものではない。例えば、図１に示す帯電ロール１０において、軸体１２と弾性体層１４との間に他の弾性体層を備えた構成であってもよい。この場合、他の弾性体層は、帯電ロールのベースとなる層であり、弾性体層１４が帯電ロールの抵抗調整を行う抵抗調整層などとして機能する。他の弾性体層は、例えば、弾性体層１４を構成する材料として挙げられた材料のいずれかにより構成することができる。また、例えば、図１に示す帯電ロール１０において、弾性体層１４と表層１６との間に他の弾性体層を備えた構成であってもよい。この場合、弾性体層１４が帯電ロールのベースとなる層であり、他の弾性体層は、帯電ロールの抵抗調整を行う抵抗調整層などとして機能する。 The configuration of the charging roll according to the present invention is not limited to the configuration shown in FIG. For example, in the charging roll 10 shown in FIG. 1, another elastic layer may be provided between the shaft 12 and the elastic layer 14. In this case, the other elastic layer is a layer to be a base of the charging roll, and the elastic layer 14 functions as a resistance adjusting layer or the like for adjusting the resistance of the charging roll. The other elastic layer can be made of, for example, any of the materials mentioned as the material of the elastic layer 14. Also, for example, in the charging roll 10 shown in FIG. 1, another elastic layer may be provided between the elastic layer 14 and the surface layer 16. In this case, the elastic layer 14 is a layer to be a base of the charging roll, and the other elastic layers function as a resistance adjusting layer or the like for adjusting the resistance of the charging roll.
　以下、実施例および比較例を用いて本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail using examples and comparative examples.
（実施例１～１１、比較例１～８）
＜導電性ゴム組成物の調製＞
　イソプレンゴム１００質量部に対し、カーボンブラック３０質量部、酸化亜鉛６質量部、ステアリン酸２質量部、硫黄１質量部、チアゾール系加硫促進剤０．５質量部、チラウム系加硫促進剤０．５質量部、重質炭酸カルシウム５０質量部を配合し、５０℃に温度調節した密閉型ミキサーを用いて１０分間混練し、導電性ゴム組成物を調製した。 (Examples 1 to 11, Comparative Examples 1 to 8)
<Preparation of Conductive Rubber Composition>
Based on 100 parts by mass of isoprene rubber, 30 parts by mass of carbon black, 6 parts by mass of zinc oxide, 2 parts by mass of stearic acid, 1 part by mass of sulfur, 0.5 parts by mass of thiazole based vulcanization accelerator, 0 thiraum based vulcanization accelerator A conductive rubber composition was prepared by blending 5 parts by mass and 50 parts by mass of ground calcium carbonate, and kneading for 10 minutes using a closed-type mixer whose temperature was adjusted to 50 ° C.
　導電性ゴム組成物の材料として、以下の材料を準備した。
・ゴム成分
　イソプレンゴム（ＩＲ）［ＪＳＲ（株）製、「ＪＳＲ　ＩＲ２２００」］
・導電剤
　カーボンブラック（電子導電剤）［キャボットジャパン（株）製、「ショウブラックＮ７６２」］
・酸化亜鉛［堺化学工業（株）製、「酸化亜鉛２種」］
・ステアリン酸［日本油脂（株）製、「ステアリン酸さくら」］
・硫黄［鶴見化学工業（株）製、「粉末硫黄」］
・加硫促進剤
　チアゾール系加硫促進剤［大内新興化学工業（株）製、「ノクセラーＤＭ」］
　チラウム系加硫促進剤［大内新興化学工業（株）製、「ノクセラーＴＲＡ」］
・無機フィラー粒子
　重質炭酸カルシウム［白石カルシウム（株）製、「ホワイトンＢ」、平均粒径３．６μｍ］ The following materials were prepared as materials for the conductive rubber composition.
-Rubber component Isoprene rubber (IR) [manufactured by JSR Corp., "JSR IR 2200"]
・ Conductive agent carbon black (electronic conductive agent) [Cabot Japan KK, "Show Black N762"]
・ Zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., “Zinc oxide 2”)
・ Stearic acid (manufactured by NOF Corp., "Stearic Acid Sakura")
・ Sulfur [made by Tsurumi Chemical Industries, Ltd., "powdered sulfur"]
・ Vulcanization accelerator Thiazole-based vulcanization accelerator [Ouchi Shinko Chemical Co., Ltd. product, "Noxceller DM"]
Thiraum-based vulcanization accelerator [Ouchi Shinko Chemical Co., Ltd. product, "Nocceller TRA"]
· Inorganic filler particles Heavy calcium carbonate [Shiroishi Calcium Co., Ltd., "Whiteton B", average particle size 3.6 μm]
＜弾性体層の作製＞
　直径６ｍｍ、快削鋼（ＳＵＭ）製の芯金の外周に、押出成形装置を用いて、調製した導電性ゴム組成物をクラウン形状に押出成形した。具体的には、押出成形装置のダイスの円形口部に対して上記芯金を通過させながら、ダイスと芯金との隙間に導電性ゴム組成物を供給することにより、芯金の外周に弾性体層を押出成形した。この押出成形の際、芯金の通過速度を変化させ、芯金の長手方向に対する導電性ゴム組成物の付着量を制御することにより、弾性体層前駆体の形状をクラウン形状とした。次いで、これを１８０℃で３０分間加熱処理した。これにより芯金の外周に所定の弾性体層（厚み１．５ｍｍ）を形成した。 <Production of elastic layer>
Using an extrusion molding apparatus, the prepared conductive rubber composition was extruded into a crown shape around the periphery of a core metal made of free-cutting steel (SUM) with a diameter of 6 mm. Specifically, the conductive rubber composition is supplied to the gap between the die and the cored bar while passing the cored bar to the circular opening of the die of the extrusion molding apparatus, whereby the outer periphery of the cored bar is made elastic. The body layer was extruded. At the time of this extrusion molding, the shape of the elastic layer precursor is made into a crown shape by changing the passing speed of the core metal and controlling the adhesion amount of the conductive rubber composition in the longitudinal direction of the core metal. It was then heat treated at 180 ° C. for 30 minutes. Thereby, a predetermined elastic layer (thickness 1.5 mm) was formed on the outer periphery of the cored bar.
＜表層の作製＞
　表１、２に記載の配合量（質量部）となるように粒子とバインダー樹脂を配合し、メチルエチルケトン（ＭＥＫ）２００質量部を加え、所定時間、超音波をかけて混合攪拌することにより、表層形成用の液状組成物を調製した。次いで、この液状組成物を弾性体層の外周面にロールコートし、熱処理を施すことにより、弾性体層の外周に表層を形成した。これにより、帯電ロールを作製した。 <Preparation of surface>
The particles and the binder resin are blended so that the blending amounts (mass parts) described in Tables 1 and 2 are added, 200 parts by mass of methyl ethyl ketone (MEK) is added, and ultrasonic waves are applied for a predetermined time to mix and stir. A liquid composition for formation was prepared. Next, the liquid composition was roll-coated on the outer peripheral surface of the elastic layer, and heat treatment was performed to form a surface layer on the outer periphery of the elastic layer. Thereby, a charging roll was produced.
（実施例１２～１８）
　表３に記載の配合量（質量部）となるように粒子とバインダー樹脂と有機酸溶液を配合し、メチルエチルケトン（ＭＥＫ）２００質量部を加え、所定時間（１０分）混合攪拌することにより、表層形成用の液状組成物を調製した。この際、超音波をかけなかった。得られた表層形成用組成物を用いた以外は他の実施例と同様にして、帯電ロールを作製した。 (Examples 12 to 18)
The particles, the binder resin and the organic acid solution are blended so as to be the blending amount (mass part) described in Table 3, 200 parts by mass of methyl ethyl ketone (MEK) is added, and the surface layer is mixed and stirred for a predetermined time (10 minutes). A liquid composition for formation was prepared. At this time, ultrasound was not applied. A charge roll was produced in the same manner as in the other examples except that the obtained composition for surface layer formation was used.
　表層材料として用いた材料は以下の通りである。
・バインダー樹脂（ナイロン）：鉛市製「ファインレジンＦＲ－１０４」
・バインダー樹脂（アクリル）：根上工業製「パラクロンＷ１９７Ｃ」
・ナイロン粒子＜１＞：平均粒子径３０μｍ、ダイセル・ヒュルス製「ダイアミド１１１８」
・ナイロン粒子＜２＞：平均粒子径２０μｍ、ダイセル・ヒュルス製「ダイアミド２１５８」
・ナイロン粒子＜３＞：平均粒子径５０μｍ、アルケマ製「オルガソール２００２ＥＳ５ＮＡＴ１」
・ナイロン粒子＜４＞：平均粒子径５．０μｍ、ダイセル・ヒュルス製「ダイアミド２０７０」
・ナイロン粒子＜５＞：平均粒子径１０μｍ、ダイセル・ヒュルス製「ダイアミド２１５９」
・ナイロン粒子＜６＞：平均粒子径６０μｍ、アルケマ製「オルガソール２００２ＥＳ６ＮＡＴ１」
・シリカ粒子＜１＞：平均粒子径５．０μｍ、富士シリシア製「サイリシア４５０」
・シリカ粒子＜２＞：平均粒子径３．０μｍ、ＡＧＣエスアイテック製「サンスフェアＬ－３１」
・シリカ粒子＜３＞：平均粒子径１２μｍ、ＡＧＣエスアイテック製「サンスフェアＨ－１２２」
・シリカ粒子＜４＞：平均粒子径２．０μｍ、富士シリシア製「サイリシア４３６」
・有機酸＜１＞：クエン酸、５質量％クエン酸水溶液使用
・有機酸＜２＞：シュウ酸、５質量％シュウ酸水溶液使用
・有機酸＜３＞：ギ酸、５質量％ギ酸水溶液使用
・有機酸＜４＞：酢酸、５質量％酢酸水溶液使用
ただし、表の配合量は、水を除いた量である。 The materials used as the surface layer material are as follows.
・ Binder resin (nylon): "FINE RESIN FR-104" made by Lead City
・ Binder resin (acrylic): "Parakron W197C" made by Negami Industrial
Nylon particles <1>: average particle size 30 μm, manufactured by Daicel-Huls "Diamide 1118"
Nylon particles <2>: average particle diameter 20 μm, manufactured by Daicel-Huls "Diamide 2158"
-Nylon particles <3>: average particle diameter 50 μm, manufactured by Arkema "Orgasol 2002 ES 5 NAT 1"
Nylon particles <4>: average particle diameter 5.0 μm, manufactured by Daicel-Huls "Diamide 2070"
Nylon particles <5>: average particle diameter 10 μm, manufactured by Daicel-Huls "Diamide 2159"
-Nylon particles <6>: average particle diameter 60 μm, manufactured by Arkema "Orgasol 2002 ES 6 NAT 1"
Silica particles <1>: average particle diameter 5.0 μm, “Silysia 450” manufactured by Fuji Silysia
Silica particles <2>: average particle diameter 3.0 μm, manufactured by AGC S-ITECH “Sunsphere L-31”
Silica particles <3>: average particle diameter 12 μm, manufactured by AGC S-ITECH "Sunsphere H-122"
Silica particles <4>: average particle diameter 2.0 μm, “Silysia 436” manufactured by Fuji Silysia
・ Organic acid <1>: Citric acid, 5 mass% citric acid aqueous solution use ・ Organic acid <2>: Oxal acid, 5 mass% oxalic acid aqueous solution use ・ Organic acid <3>: Formic acid, 5 mass% formic acid aqueous solution use Organic acid <4>: acetic acid, 5 mass% acetic acid aqueous solution However, the compounding quantity of a table | surface is the quantity except water.
　使用した粒子について、各測定を行った。また、作製した各帯電ロールの表層について、各測定を行った。そして、作製した各帯電ロールについて、帯電性に関係する画像評価を行った。また、耐久性を併せて評価した。実施例１，７，１２～１８については、大径粒子同士の凝集体の個数を調べ、さらに耐久後の画像評価を行った。評価結果および表層形成用組成物の配合組成を以下の表に示す。 Each measurement was performed about the used particle. Moreover, each measurement was performed about the surface layer of each produced charging roll. And the image evaluation related to chargeability was performed about each produced charging roll. In addition, the durability was also evaluated. In Examples 1, 7 and 12 to 18, the number of aggregates of large diameter particles was examined, and image evaluation after durability was performed. The evaluation results and the composition of the surface layer forming composition are shown in the following table.
（粒子の硬度比）
　Ｆｉｓｃｈｅｒ社製「フィッシャースコープＨＭ２０００ＬＴ」もしくは相当の測定器を用い、触芯は平面圧子を用い、粒子に対して１ｍＮを押し込んだ時のユニバーサル硬さ（ＨＵ）を測定値とした。 (The hardness ratio of particles)
Using a "Fisherscope HM2000LT" manufactured by Fischer Co. or an equivalent measuring instrument, using a planar indenter, the universal hardness (HU) when 1 mN was pressed into the particles was taken as the measured value.
（粒子の変形量）
　ユニバーサル硬度計で測定した。押し込み荷重５０ｍＮをかけた時の粒子径と荷重をかける前の粒子径より算出した。 (Deformation amount of particle)
It measured with the universal hardness tester. The particle size was calculated from the particle size when a pressing load of 50 mN was applied and the particle size before the load was applied.
（粒子の凝集体の大きさ）
　小径粒子を含む粒子の凝集体の大きさは、表層の表面写真を撮影し、任意の５箇所においてそれぞれ小径粒子を含む粒子の凝集体の最大距離を３つ測定し、合計１５点の平均により表した。 (Size of particle aggregates)
The size of the aggregate of particles containing small-diameter particles, take a picture of the surface of the surface layer, measure the maximum distance of three aggregates of particles containing small-diameter particles at any five locations, and average the total of 15 points expressed.
（粒子間の平均距離）
　大径粒子間の平均距離は、表層の表面写真を撮影し、任意の５箇所においてそれぞれ大径粒子間の距離を３つ測定し、合計１５点の平均により表した。小径粒子間の平均距離および他の粒子間の平均距離も同様に測定した。 (Average distance between particles)
The average distance between the large diameter particles was obtained by taking a surface photograph of the surface layer, measuring the distance between three large diameter particles at any five points, and expressing the average of a total of 15 points. The average distance between small particles and the average distance between other particles were also measured.
（粒子部の凸部高さ）
　レーザー顕微鏡（キーエンス製「ＶＫ－９５１０」）を用いて断面を観察することにより測定した。大径粒子部の凸部高さは、粒子が存在していない部分における表層の表面から大径粒子が存在している部分における頂部の表層の表面までの高さで表した。任意の位置の５か所について大径粒子部の凸部高さをそれぞれ測定し、その平均によって表した。小径粒子部の凸部高さおよび他の粒子部の凸部高さも同様に測定した。 (Height of convex part of particle part)
It measured by observing a cross section using a laser microscope ("VK-9510" made from Keyence). The height of the convex portion of the large diameter particle portion was represented by the height from the surface of the surface layer in the portion where no particle is present to the surface of the surface portion of the top in the portion where the large diameter particle is present. The heights of the convex portions of the large diameter particle portions were measured at five positions at arbitrary positions, and the heights were expressed by the average. The heights of the protrusions of the small diameter particles and the heights of the protrusions of the other particles were also measured.
（画像評価：横スジ）
　作製した帯電ロールを実機（ＨＰ製「ＣＬＪ４５２５ｄｎ」）のカートリッジ（ブラック）に取り付け、１５℃×１０％ＲＨ環境下にて２５％濃度ハーフトーンにて画出しを行った。初期または２万枚耐久後の評価を行った。画像に横スジがなかったものを特に良好「◎」、画像に横スジがほとんどなかったものを良好「○」、画像に横スジが現れ、トナー付着による画像の影響が大きかったものを不良「×」とした。 (Image evaluation: Horizontal streaks)
The produced charging roll was attached to a cartridge (black) of a real machine ("CLJ4525dn" manufactured by HP), and image formation was performed with a 25% density halftone under an environment of 15 ° C x 10% RH. Evaluation was made after the initial or 20,000 sheets endurance. Images with no lateral streaks are particularly good "◎", those with few lateral streaks in the image are good "○", lateral streaks appear in the image, and those with large toner effects are poor. X.
（画像評価：均一性）
　作製した帯電ロールを実機（ＨＰ製「ＣＬＪ４５２５ｄｎ」）のカートリッジ（ブラック）に取り付け、１５℃×１０％ＲＨ環境下にて２５％濃度ハーフトーンにて画出しを行った。初期または２万枚耐久後の評価を行った。画像にムラがなかったものを良好「○」、画像にムラが生じたものを不良「×」とした。 (Image evaluation: uniformity)
The produced charging roll was attached to a cartridge (black) of a real machine ("CLJ4525dn" manufactured by HP), and image formation was performed with a 25% density halftone under an environment of 15 ° C x 10% RH. Evaluation was made after the initial or 20,000 sheets endurance. Those with no unevenness in the image are regarded as good "○", and those with unevenness in the image are regarded as bad "×".
（耐久性評価：ロール汚れ）
　作製した帯電ロールを実機（ＨＰ製「ＣＬＪ４５２５ｄｎ」）のカートリッジ（ブラック）に取り付け、１５℃×１０％ＲＨ環境下にて２万枚耐久後に、ロール外観を目視にて観察した。この際、白い外添剤の汚れがロール全面に付着しており、明らかに画像不良が生じる量である場合を不良「×」、スジ状の汚れがロール表面に微量付着しているが、白い外添剤が軽微に付着している汚れであり画像不良が生じない量である場合を良好「○」、スジ状の汚れがロール表面に発生していない場合を最も良好「◎」とした。 (Durability evaluation: Roll dirt)
The manufactured charging roll was attached to a cartridge (black) of a real machine (“CLJ 4525 dn” manufactured by HP), and after appearance of 20,000 sheets under a 15 ° C. × 10% RH environment, the roll appearance was visually observed. Under the present circumstances, the stain of a white external additive has adhered to the roll whole surface, and when it is the quantity which an image defect produces clearly, it is a defect "x" and a trace of stain adheres to the roll surface in a small amount. The case in which the external additive was a slight stain and was an amount that would not cause an image defect was regarded as good "○", and the case where no streaky stain occurred on the roll surface was regarded as the best "◎".
（大径粒子同士の凝集体の個数）
　表層の表面写真を撮影し、任意の５箇所においてそれぞれ大径粒子同士の凝集体の個数（個／ｍｍ２）を計測し、平均により表した。 (Number of agglomerates of large diameter particles)
The surface photograph of the surface layer was taken, and the number (aggregation / mm 2 ) of aggregates of large-diameter particles was measured at any five places, and the average was shown.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　比較例１、２は、所定の大径粒子を含むが所定の小径粒子を含んでいないため、帯電均一性が不十分で画像の均一性に劣っている。比較例３は、所定の小径粒子を含むが所定の大径粒子を含んでいないため、感光ドラムとのギャップが不十分で画像に横スジが発生した。比較例４は、所定の大径粒子および所定の小径粒子を含むが所定の小径粒子の含有量が少なすぎるため、帯電均一性が不十分で画像の均一性に劣っている。比較例５は、所定の大径粒子とその大径粒子よりもさらに大径の粒子を含むが所定の小径粒子を含んでいないため、帯電均一性が不十分で画像の均一性に劣っている。比較例６は、所定の小径粒子よりも小径の粒子と所定の大径粒子を含むが所定の小径粒子を含んでいないため、帯電均一性が不十分で画像の均一性に劣っている。比較例７は、所定の大径粒子および所定の小径粒子を含むが所定の小径粒子の含有量が多すぎるため、小径粒子を含む凝集体の大きさが大きすぎて、帯電均一性が不十分で画像の均一性に劣っている。比較例８は、所定の大径粒子および所定の小径粒子を含むが超音波による分散が不十分であるため、小径粒子を含む凝集体の大きさが大きすぎて、帯電均一性が不十分で画像の均一性に劣っている。 Comparative Examples 1 and 2 contain predetermined large-diameter particles but do not contain predetermined small-diameter particles, and therefore the charging uniformity is insufficient and the image uniformity is inferior. Comparative Example 3 contains predetermined small-diameter particles but does not contain predetermined large-diameter particles, so the gap between the photosensitive drum and the photosensitive drum is insufficient, and a lateral streak occurs in the image. Comparative Example 4 contains predetermined large-diameter particles and predetermined small-diameter particles, but since the content of predetermined small-diameter particles is too small, charging uniformity is insufficient and image uniformity is poor. Comparative Example 5 contains predetermined large-sized particles and particles having a diameter larger than that of the large-sized particles, but does not contain predetermined small-sized particles, so charging uniformity is insufficient and image uniformity is inferior. . Comparative Example 6 includes particles having a diameter smaller than a predetermined small particle and predetermined large particles but does not contain a predetermined small particle, so charging uniformity is insufficient and image uniformity is inferior. In Comparative Example 7, although the content of the predetermined small diameter particles is too large although the predetermined large diameter particles and the predetermined small diameter particles are included, the size of the aggregate including the small diameter particles is too large and the charging uniformity is insufficient. Is inferior to the uniformity of the image. Comparative Example 8 contains predetermined large-diameter particles and predetermined small-diameter particles, but the dispersion by ultrasonic waves is insufficient. Therefore, the size of the aggregate including small-diameter particles is too large, and charging uniformity is insufficient. Poor in image uniformity.
　これに対し、実施例は、所定の大径粒子および所定の小径粒子を含み、所定の小径粒子の含有量が所定範囲内であり、小径粒子を含む粒子の凝集体の大きさが所定範囲内であるため、感光ドラムとの間のギャップが十分に確保されているとともに帯電均一性も満足するものとなり、画像に横スジが発生せず、画像の均一性にも優れていた。また、耐久性にも優れていた。そして、実施例同士の比較では、大径粒子と小径粒子の硬度比が０．５以下であると、耐久時の汚れが一層低減し、特に耐久性に優れることがわかる。 On the other hand, in the embodiment, the content of the predetermined small diameter particles is within the predetermined range, and the size of the aggregate of the particles including the small diameter particles is within the predetermined range. Therefore, the gap between the photosensitive drum and the photosensitive drum was sufficiently secured and the charging uniformity was also satisfactory, and no lateral streaks occurred in the image, and the uniformity of the image was also excellent. Also, the durability was excellent. And in comparison of Examples, when the hardness ratio of a large diameter particle and a small diameter particle is 0.5 or less, the dirt at the time of endurance decreases further, and it turns out that it is excellent in especially endurance.
　実施例１と実施例１２～１７、実施例７と実施例１８、比較例８の比較から、表層がさらに有機酸を含有すると、超音波をかけなくても小径粒子を含む粒子の凝集体の大きさを小さく抑えることができる。また、大径粒子同士の凝集を抑えることができる。また、大径粒子間の距離をより大きくすることができる。そして、これらにより、画質の向上およびロール汚れの低減が確認された。 From the comparison of Example 1 with Examples 12 to 17, Example 7 with Example 18 and Comparative Example 8, when the surface layer further contains an organic acid, an aggregate of particles including small diameter particles even without applying ultrasonic waves. The size can be kept small. Moreover, aggregation of large diameter particles can be suppressed. In addition, the distance between the large diameter particles can be further increased. As a result, improvement in image quality and reduction in roll contamination were confirmed.
　以上、本発明の実施形態・実施例について説明したが、本発明は上記実施形態・実施例に何ら限定されるものではなく、本発明の趣旨を逸脱しない範囲内で種々の改変が可能である。 As mentioned above, although embodiment and Example of this invention were described, this invention is not limited at all to the said embodiment and Example, A various change is possible within the range which does not deviate from the meaning of this invention .

Claims (8)

  1. 　軸体と、前記軸体の外周に形成された弾性体層と、前記弾性体層の外周に形成された表層と、を備え、
    　前記表層は、バインダー樹脂と、平均粒子径１５μｍ以上５０μｍ以下の大径粒子と、平均粒子径３μｍ以上１５μｍ未満の小径粒子と、を含有し、
    　前記小径粒子の含有量が、前記バインダー樹脂１００質量部に対し、５～５０質量部の範囲内であり、
    　前記表層に含まれる前記小径粒子を含む粒子の凝集体の大きさが６μｍ以上５０μｍ以下であることを特徴とする電子写真機器用帯電ロール。     A shaft, an elastic layer formed on the outer periphery of the shaft, and a surface layer formed on the outer periphery of the elastic layer;
    The surface layer contains a binder resin, large-diameter particles having an average particle diameter of 15 μm to 50 μm, and small-diameter particles having an average particle diameter of 3 μm to less than 15 μm.
    The content of the small diameter particles is in the range of 5 to 50 parts by mass with respect to 100 parts by mass of the binder resin,
    What is claimed is: 1. A charging roll for an electrophotographic apparatus, wherein the size of an aggregate of particles including the small diameter particles contained in the surface layer is 6 μm or more and 50 μm or less.
  2. 　前記表層が、前記バインダー樹脂１００質量部に対し、有機酸を０．１～１０質量部含有することを特徴とする請求項１に記載の電子写真機器用帯電ロール。 The charging roll for an electrophotographic apparatus according to claim 1, wherein the surface layer contains 0.1 to 10 parts by mass of an organic acid with respect to 100 parts by mass of the binder resin.
  3. 　前記有機酸が、水酸基を有する有機酸であることを特徴とする請求項２に記載の電子写真機器用帯電ロール。 The charging roll for an electrophotographic apparatus according to claim 2, wherein the organic acid is an organic acid having a hydroxyl group.
  4. 　前記大径粒子と前記小径粒子の平均粒子径の差が、１０μｍ以上であることを特徴とする請求項１から３のいずれか１項に記載の電子写真機器用帯電ロール。 The charging roll for an electrophotographic apparatus according to any one of claims 1 to 3, wherein a difference between an average particle diameter of the large-diameter particles and an average particle diameter of the small-diameter particles is 10 μm or more.
  5. 　前記小径粒子間の平均距離が、４０μｍ以下であることを特徴とする請求項１から４のいずれか１項に記載の電子写真機器用帯電ロール。 The charging roll for electrophotographic equipment according to any one of claims 1 to 4, wherein an average distance between the small diameter particles is 40 μm or less.
  6. 　前記大径粒子間の平均距離が、６０μｍ以上であることを特徴とする請求項１から５のいずれか1項に記載の電子写真機器用帯電ロール。 The charging roll for an electrophotographic apparatus according to any one of claims 1 to 5, wherein an average distance between the large diameter particles is 60 μm or more.
  7. 　前記大径粒子の硬度が、前記小径粒子の硬度よりも小さいことを特徴とする請求項１から６のいずれか1項に記載の電子写真機器用帯電ロール。 The charging roll for an electrophotographic apparatus according to any one of claims 1 to 6, wherein the hardness of the large diameter particles is smaller than the hardness of the small diameter particles.
  8. 　前記小径粒子が、シリカ粒子であることを特徴とする請求項１から７のいずれか1項に記載の電子写真機器用帯電ロール。 The charging roller according to any one of claims 1 to 7, wherein the small diameter particles are silica particles.
PCT/JP2017/027144 2016-09-30 2017-07-27 Charging roll for electrographic device WO2018061441A1 (en)

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JP2019003171A (en) * 2017-06-15 2019-01-10 キヤノン株式会社 Image formation apparatus, electrification member, cartridge and manufacturing method of electrification member
WO2020158550A1 (en) * 2019-01-30 2020-08-06 住友理工株式会社 Charging roll for electrophotographic equipment

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JP2017032821A (en) * 2015-08-03 2017-02-09 株式会社ブリヂストン Charging roller
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JP2019003171A (en) * 2017-06-15 2019-01-10 キヤノン株式会社 Image formation apparatus, electrification member, cartridge and manufacturing method of electrification member
JP7034813B2 (en) 2017-06-15 2022-03-14 キヤノン株式会社 Image forming device, charging member, cartridge, manufacturing method of charging member
WO2020158550A1 (en) * 2019-01-30 2020-08-06 住友理工株式会社 Charging roll for electrophotographic equipment
JP2020122867A (en) * 2019-01-30 2020-08-13 住友理工株式会社 Charging roll for electrophotographic apparatus
JP7079741B2 (en) 2019-01-30 2022-06-02 住友理工株式会社 Charging roll for electrophotographic equipment

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