JP2017015948A - Element for charging, manufacturing method of element for charging, charger, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charger using an element for charging that discharges electrons through an action of an electric field to charge a charging target body, and make it possible to uniformly charge a surface of the charging target body while suppressing the generation of a corona product, such as ozone, by reducing a voltage to be applied to the element for charging, and make it possible to reduce a manufacturing cost of the element for charging.SOLUTION: An element for charging 21 is used in a charger 20, in which an element layer 21b having a carbon nanotube dispersed in a resin is provided on a surface of a conductive substrate 21a facing an image carrier 11. In the charger 20, a drawing electrode 22 is provided between the element for charging 21 and image carrier 11; a voltage is applied to the drawing electrode 22; and electrons are discharged from the element for charging 21 through an action of an electric field to charge the image carrier 11.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a charging element used for charging an object to be charged, a method for manufacturing a charging element for manufacturing a charging element, a charging device using the charging element, and a surface of an image carrier by the charging device. The present invention relates to an image forming apparatus that is charged. In particular, in order to charge an object to be charged such as an image carrier in an image forming apparatus by a charging device using a charging element, the voltage applied to the charging element is lowered to generate discharge products such as ozone. The present invention is characterized in that the surface of an object to be charged such as an image carrier can be uniformly charged while suppressing the manufacturing cost and the like of the charging element.

  Conventionally, in an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a composite machine of these, the surface of a charged body made of an image carrier is charged by a charging device, and the surface of the image carrier thus charged is charged. An image is formed by forming an electrostatic latent image.

  In such an image forming apparatus, in order to charge the surface of the image carrier with the charging device, conventionally, the charging electrode is generally arranged so as to face the surface of the image carrier with a predetermined interval. , A non-contact type charging device in which the surface of the image carrier is charged by corona discharge between the charging electrode and the surface of the image carrier, a charging roller such as a conductive rubber roller, or a conductive material. A charging brush such as a brush roller is brought into contact with the surface of the image carrier, and a discharge is caused in a minute gap between the charging roller or the charging brush and the image carrier to charge the surface of the image carrier. Proposed.

  Here, in the case of a non-contact type charging device, generally a wire of about 50 μm or a saw blade is used for the charging electrode, and a high voltage is applied between the charging electrode and the image carrier to charge the charging. In order to cause corona discharge between the electrode for use and the surface of the image carrier, a high-voltage power supply is required, and the amount of discharge products such as ozone increases, resulting in various problems in terms of environment, cost, and energy saving. It was. Further, although a scorotron type in which a mesh-like grid electrode for adjusting the amount of discharge electrons is provided between the charging electrode and the image carrier is also used, the above-described problems still exist.

  On the other hand, when the surface of the image carrier is charged by bringing a charging roller or brush into contact with the surface of the image carrier and causing a discharge in a minute gap between the charging roller or brush and the image carrier, As compared with the case of corona discharge, discharge can be performed at a lower voltage, and generation of discharge products such as ozone can be reduced.

  However, when the charging roller or charging brush is brought into contact with the surface of the image carrier, uneven charging occurs on the surface of the image carrier due to uneven contact with the surface of the image carrier or the charging roller due to contact with the image carrier. In addition, there is a problem that the charging brush and the charging brush become dirty, and it is necessary to use a high-functional material for the charging roller and charging brush, and a relatively advanced production technology is also required to ensure quality. However, there is a problem that the cost of the charging roller and the charging brush is high.

  Further, in recent years, as shown in Patent Documents 1 and 2, a charging element that emits electrons by the action of an electric field has been proposed for charging a charged object such as an image carrier. ing.

  Here, as a charging element that emits electrons by the action of an electric field, an electron emitting material such as a carbon nanotube having a relatively large number of unpaired electrons in a molecule on a conductive substrate such as an emitter electrode. The one that has been proposed is proposed.

  However, since carbon nanotubes with high electron emission performance are strong in self-aggregation due to van der Waals force between molecules, they are provided in an aggregated state on a conductive substrate, and the carbon nanotubes are in an aggregated state in this way. Even if an electric field is applied to the charging element, electrons are not properly emitted from the carbon nanotubes toward the charged object such as the image carrier, and the charged object such as the image carrier cannot be appropriately charged. There was a problem.

  Here, in Patent Document 1, as a charging element, a long portion of each carbon nanotube is directed to a member to be charged in a state in which the carbon nanotube itself is individually dispersed on a conductive substrate made of an emitter electrode. The orientation is shown as follows.

  However, as in Patent Document 1, in a state in which the carbon nanotubes are individually dispersed on the conductive substrate made of the emitter electrode, the long portions of the carbon nanotubes are oriented so as to face the charged body. However, there is a problem that it is very troublesome and difficult, and it takes time to manufacture the charging element and the manufacturing cost is high.

Japanese Patent Application Laid-Open No. 2002-279885 JP 2006-323366 A

  An object of the present invention is to solve the above-described various problems in charging a charged object such as an image carrier in an image forming apparatus by a charging device using a charging element.

  In the present invention, a charging element that discharges electrons by the action of an electric field to charge an object to be charged is used, and the voltage applied to the charging element is lowered to suppress the generation of discharge products such as ozone. However, it is an object of the present invention to make it possible to uniformly charge the surface of an object to be charged such as an image carrier and to reduce the manufacturing cost of the charging element.

  In the charging element according to the present invention, in order to solve the above-described problems, the surface of the conductive substrate facing the charged body in the charging element that discharges electrons by the action of an electric field to charge the charged body. In addition, an element layer in which carbon nanotubes are dispersed in a resin is provided.

  In this charging element, when the carbon nanotubes are dispersed in the resin in the element layer, it is preferable to align the long part of the carbon nanotubes toward the member to be charged. In this way, when the carbon nanotubes are oriented in such a way that the long portions of the carbon nanotubes are directed toward the object to be charged, and the carbon nanotubes are dispersed in the resin, the amount of the carbon nanotubes to be dispersed in the resin is reduced. The number of ends of the carbon nanotubes that emit electrons facing each other increases, and even when the voltage applied to the charging element is lowered, the charged object can be uniformly and appropriately charged.

  Further, in this charging element, when the end of the long part of the carbon nanotube is exposed on the surface of the element layer facing the charged body, the end of the long part of the exposed carbon nanotube is removed. Electrons are easily emitted, and even if the voltage applied to the charging element is lowered, the member to be charged is appropriately charged.

  In manufacturing the charging element according to the present invention, a resin in which carbon nanotubes are dispersed is applied to the surface of the conductive substrate, the resin is cured while applying an electric field, and the carbon nanotubes are dispersed in the resin. An element layer can be provided.

  Further, in curing the resin in which the carbon nanotubes are dispersed while applying the electric field as described above, the electric field is applied so that the long part of the carbon nanotube is directed toward the member to be charged. It can be oriented so as to be directed to the member to be charged.

  In addition, after curing the resin in which the carbon nanotubes are dispersed as described above, the surface of the element layer facing the charged body is surface-treated so that the long part of the carbon nanotube facing the charged body is The end can be exposed.

  In manufacturing the charging element as described above, a thermosetting epoxy resin can be used as the resin, and an imidazolium salt can be contained in the thermosetting epoxy resin. Here, when an imidazolium salt is contained in the thermosetting epoxy resin as described above, the imidazolium salt disperses the carbon nanotubes in the curing agent and the thermosetting epoxy resin that cure the thermosetting epoxy resin. This thermosetting epoxy resin can be cured at a relatively low temperature in a short time with the carbon nanotubes dispersed in the thermosetting epoxy resin.

  In the charging device of the present invention, an extraction electrode is provided between the charging element and the member to be charged, and a voltage is applied to the extraction electrode so that electrons are emitted from the charging element by the action of an electric field. In this way, the charged body is charged by being led to the discharged charged body.

  Further, when the extraction electrode is provided between the charging element and the charged body as described above, the distance d1 between the charging element and the extraction electrode and the distance d2 between the extraction electrode and the charged body. Preferably satisfy the relationship of d1 ≦ d2. This is because when the distance d1 between the charging element and the extraction electrode is longer than the distance d2 between the extraction electrode and the charged body, electrons are emitted from the charging element toward the charged body by the action of the electric field. Therefore, it is necessary to increase the voltage applied to the extraction electrode, a high-voltage power supply is required, the amount of discharge products such as ozone increases, and the extraction electrode, the object to be charged, This is because leakage may occur between the two.

  In the image forming apparatus according to the present invention, the surface of the image carrier is charged using the charging device as described above.

  In the present invention, as described above, a charging element in which an element layer in which carbon nanotubes are dispersed in a resin is provided on the surface of a conductive substrate facing a member to be charged, and an electric field is applied to the charging element. As a result, electrons are discharged from the charging element to charge the object to be charged. Therefore, compared to the case of corona discharge, the voltage applied to the charging element is lowered to reduce the discharge product such as ozone. It becomes possible to uniformly charge the surface of an object to be charged such as an image carrier while suppressing the generation.

  Further, in the present invention, since the carbon nanotubes are dispersed in the resin as described above, the carbon nanotubes themselves are individually dispersed on the surface of the conductive substrate, and each carbon nanotube is individually directed to the object to be charged. In comparison with the case where the carbon nanotubes are dispersed on the surface of the conductive substrate, it is possible to easily align the long portions of the carbon nanotubes toward the charged body, It is possible to reduce the time for manufacturing the charging element as described above and to reduce the manufacturing cost.

1 is a schematic explanatory diagram of an image forming apparatus using a charging device according to an embodiment of the present invention. In the charging device according to the above-described embodiment, a charging element in which an element layer is provided on the surface of a conductive substrate is shown, (A) is a schematic plan view viewed from a surface facing an image carrier, and (B) is a schematic diagram. It is sectional drawing. In the charging device according to the above-described embodiment, an extraction electrode is provided between the charging element and the image carrier, and an electric field is applied between the extraction electrode and the charging element, so that the electron from the charging element. FIG. 3 is a schematic explanatory view showing a state in which the image carrier is charged by discharging

  Next, a charging element, a charging element manufacturing method, a charging device, and an image forming apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Note that the charging element, the method for manufacturing the charging element, the charging device, and the image forming apparatus according to the present invention are not limited to those shown in the following embodiments, and may be changed as appropriate without departing from the scope of the invention. It can be implemented.

  Here, in the image forming apparatus 10 in the embodiment shown in FIG. 1, an image carrier 11 made of a rotating photosensitive drum is used as a member to be charged, and charging provided along the axial direction of the image carrier 11 is performed. The surface of the rotating image carrier 11 is charged by the device 20.

  The surface of the image carrier 11 thus charged is exposed according to image information by a latent image forming apparatus 12 using a laser or the like, and an electrostatic latent image is formed on the surface of the image carrier 11. I am doing so.

  Next, toner is supplied from the developing device 13 to the portion of the electrostatic latent image formed on the surface of the image carrier 11 in this way, and a toner image corresponding to the electrostatic latent image is formed on the surface of the image carrier 11. Like to do.

  Then, the toner image formed on the surface of the image carrier 11 in this manner is guided to a position facing the roller-like transfer device 14, and a recording sheet is provided between the image carrier 11 and the transfer device 14. The toner image formed on the surface of the image carrier 11 is transferred to the recording sheet S from the transfer device 14, and the recording sheet S to which the toner image is transferred in this way is guided to the fixing device 15. In 15, the toner image is fixed on the recording sheet S.

  Further, the toner remaining on the surface of the image carrier 11 without being transferred to the recording sheet S is removed from the surface of the image carrier 11 by the cleaning device 16, and then the surface of the image carrier 11 is changed as described above. The charging device 20 is charged.

  Here, in the charging device 20 in this embodiment, as shown in FIGS. 1 and 2A and 2B, the carbon nanotubes in the resin are formed on the surface of the conductive substrate 21a facing the image carrier 11. An element layer 21b oriented and dispersed so that the long part of the carbon nanotube is directed toward the image carrier 11 is provided, and the end of the long part of the carbon nanotube is provided on the surface of the element layer 21b facing the image carrier 11. The charging element 21 with the exposed portion is used. In this embodiment, as the charging element 21, in the element layer 21b as described above, the long portion of the carbon nanotube is oriented and dispersed in the resin so as to face the image carrier 11, and the image is also obtained. Although the end of the long part of the carbon nanotube is exposed on the surface of the element layer 21b facing the carrier 11, the charging element 21 used in the charging device 20 does not necessarily include each carbon nanotube. The orientation is not limited to the above.

  In the charging device 20 in this embodiment, as shown in FIGS. 1 and 3, an extraction electrode 22 is provided between the charging element 21 and the image carrier 11, and the extraction electrode 22 A charging bias voltage is applied from the charging power source 23 to the conductive substrate 21 a in the charging element 21 to cause an electric field to act on the charging element 21, thereby causing the carbon nanotubes in the charging element 21 to Electrons are extracted, and the electrons thus extracted are guided to the image carrier 11 through the extraction electrode 22 so that the surface of the image carrier 11 is charged.

  Here, in the charging device 20, as the carbon nanotubes in the charging element 21, those obtained by general-purpose manufacturing methods such as an arc method, a laser ablation method, and a CVD method can be used. A material having a diameter of 95% or more, a diameter of 10 to 40 nm, and a length of 1 to 10 μm is used.

  As the resin for dispersing such carbon nanotubes, thermosetting resins such as epoxy resins, phenol resins, unsaturated polyester resins, urea resins, melamine resins, diallyl phthalate resins can be used. It is preferable to use an imidazole compound having good dispersibility with respect to the nanotube and a thermosetting epoxy resin that can be cured at a relatively low temperature in a short time. In addition, even if it is a thermosetting resin that does not undergo a curing reaction with the imidazole compound, any resin that can dissolve and / or disperse the imidazole compound and retain the carbon nanotubes in a dispersed state in the resin after thermosetting is used. can do.

  Moreover, the kind of thermosetting epoxy resin used as the resin for dispersing the carbon nanotube is not particularly limited, and bisphenol A type, bisphenol F type, polyfunctional type, flexible type, bromine, which are general-purpose epoxy resins. Bisphenol A type epoxy resin synthesized by condensation reaction of bisphenol A and epichlorohydrin can be used from the viewpoint of reaction temperature, reaction time, pot life, etc. preferable.

  The epoxy resin curing agent includes amines such as aliphatic amines, aromatic amines, and modified amines, polymercaptan curing agents such as polyamide resins, imidazoles, liquid polymercaptans, polysulfide resins, and acid anhydrides. There are latent curing agents such as boron trifluoride-amine complex, dicyandiamide, organic acid hydrazide, and light / ultraviolet curing agents, but as described above, an imidazole compound having good dispersibility to carbon nanotubes is used. It is preferable.

  Then, in the charging device 20 in this embodiment, as in the above-described charging element 21, in obtaining the element layer 21b in which the long portions of the carbon nanotubes are oriented and dispersed so as to face the image carrier 11, In curing the resin in which the carbon nanotubes are dispersed, an electric field is applied so that the long portion of the carbon nanotubes is directed from the surface of the conductive substrate 21a to the opposite surface, so that the long portion of the carbon nanotubes is an element. Orientation is directed toward the surface of the layer 21b.

  Further, as described above, in order to expose the end of the long portion of the carbon nanotube on the surface of the element layer 21b facing the image carrier 11 as in the charging element 21, the carbon nanotube as described above is used. The surface of the element layer 21b in which the long portions are oriented is uniformly scraped to a thickness of several microns, and the tips of the carbon nanotubes dispersed and oriented as described above are disposed on the surface of the element layer 21b. Try to expose.

  In the charging element 21, the width of the element layer 21 b formed on the surface of the conductive substrate 21 a is not particularly limited. However, the density of electrons emitted from the charging element 21 is increased to increase the image carrier 11. In order to uniformly charge the surface, the width of the element layer 21b is preferably 1 mm or more.

  Further, the extraction electrode 22 applies a charging bias voltage from the charging power source 23 as described above to apply an electric field to the charging element 21, and draws electrons from the carbon nanotubes in the charging element 21, Thus, it is necessary to guide the extracted electrons to the image carrier 11, and for this reason, as the extraction electrode 22, one having a shape having a gap such as a mesh shape or a grid shape is used. To.

  Then, as described above, a charging bias voltage is applied from the charging power source 23 between the extraction electrode 22 and the conductive substrate 21a in the charging element 21 to cause an electric field to act on the charging element 21, thereby In extracting the electrons from the carbon nanotubes in the charging element 21 and charging the surface of the image carrier 11, in this embodiment, as shown in FIG. 3, the conductive substrate 21 a and the extraction electrode 22 in the charging element 21 are provided. And the distance d2 between the extraction electrode 22 and the surface of the image carrier 11 satisfy the relationship d1 ≦ d2. In this case, even if the charging bias voltage applied between the extraction electrode 22 and the conductive substrate 21a in the charging element 21 is lowered from the charging power source 23, electrons are emitted from the carbon nanotubes in the charging element 21. The surface of the image carrier 11 can be appropriately extracted and appropriately charged, the amount of discharge products such as ozone can be reduced, and between the extraction electrode 22 and the image carrier 11. There is no longer a leak.

  In the charging device 20, a casing (not shown) for holding the charging element 21 and the extraction electrode 22 can be provided. A general-purpose material such as metal or plastic can be used for the casing. . Further, for the purpose of lowering the electron emission start voltage in the charging element 21, it is preferable to provide a substance that functions to enhance electron conductivity in the atmosphere of ions, electrons, etc. inside the casing. By coating the inner surface and using ultraviolet light, which is generally said to occur when electrons are emitted, by photocatalysis, ions and electrons are emitted to increase the electron carrier content in the atmosphere, thereby increasing electron conductivity. The emission start voltage can be lowered to reduce the amount of ozone generated. In addition, an electrolyte such as NaCl or sodium acetate or an aqueous electrolyte solution in which these electrolytes are dissolved in water is applied to the inner surface of the casing, and the aqueous solution is volatilized by electromagnetic waves, thermal energy, etc. during electron emission to generate ionic mist. Alternatively, it is conceivable to use a method such as applying submicron ionic powder particles to the inner surface of the casing to generate aerosol to increase the content of ions and electron carriers in the atmosphere.

  Next, when the charging device of the embodiment using the charging element as described above is used, the voltage applied to the charging element is lowered to charge the image carrier to a predetermined surface potential. A comparative example will clarify that ozone generation can be suppressed.

  Here, in the charging device of the example, a charging element manufactured as follows was used.

(Charging elements A1a to A1c)
In manufacturing the charging elements A1a to A1c,
1 part by weight of a commercially available multi-walled carbon nanotube (Sigma-Aldrich: SMW200) manufactured by CVD method, having a diameter of 4 to 11 nm, a length of 3 to 6 μm, and a carbon purity exceeding 98% ,
10 parts by weight of 1-ethyl-3-methylimidazolium hexafluorophosphate (hereinafter abbreviated as EMIPF6),
A commercially available epoxy resin (manufactured by Mitsubishi Chemical Corporation: Epicoat 828) was used at a ratio of 89 parts by weight.

  Then, after adding 1 part by weight of the multi-walled carbon nanotubes to the 10 parts by weight of EMIPF 6 over a period of 1 hour while stirring with a pestle, and further cooling to 15 ° C. with a bead mill for 1 hour, Stirring was performed to obtain a carbon nanotube dispersion. Next, 89 parts by weight of the epoxy resin was added to the carbon nanotube dispersion, and these were mixed and stirred at 25 ° C. for 15 minutes by an emulsifier to obtain an element layer coating solution A.

  The obtained device layer coating liquid A was applied onto a conductive substrate made of SUS304 having a length of 330 mm, a width of 11 mm, and a thickness of 0.1 mm.

  Here, in applying the element layer coating liquid A onto the conductive substrate, the charging element A1a is applied so that the length is 320 mm, the width is 1 mm, and the thickness is 0.1 mm. The charging element A1b is applied so that the length is 320 mm, the width is 5 mm, and the thickness is 0.1 mm. The charging element A1c is 320 mm in length, the width is 10 mm, and the thickness is 0.1 mm. It applied so that it might become.

  And after apply | coating the coating liquid A for element layers on an electroconductive board | substrate as mentioned above, applying the voltage of 100V between the said electroconductive board | substrate and the charging element, and acting an electric field, Curing was performed at 130 ° C. for 3 hours, and the surface of each of the element layers thus cured was uniformly shaved in a range of several microns with a microtome to produce charging elements A1a to A1c.

  Here, as described above, when the coating liquid for the device layer is cured while applying an electric field between the conductive substrate and the charging device, the elongated portion of the carbon nanotube is dispersed in the device layer. Is oriented from the conductive substrate toward the surface of the element layer opposite to the conductive substrate. Further, when the surface of the element layer cured as described above is evenly scraped within a range of several microns, the element layer is oriented toward the surface of the element layer on the side opposite to the conductive substrate in a dispersed state as described above. The ends of the long portions of the carbon nanotubes were exposed on the surface of the element layer, and the resin and the carbon nanotubes became microdomains on the surface of the element layer.

(Charging element A2)
In manufacturing the charging element A2, as in the case of manufacturing the charging elements A1a to A1c, the element layer coating liquid A is used, and the element layer coating liquid A is 330 mm in length. On a conductive substrate made of SUS304 having a width of 11 mm and a thickness of 0.1 mm, coating was performed so that the length was 320 mm, the width was 5 mm, and the thickness was 0.1 mm. Thereafter, the device layer coating liquid A is cured at 130 ° C. for 3 hours while applying an electric field by applying a voltage of 100 V between the conductive substrate and the charging device to charge the charging device. A2 was produced. In the charging element A2, the surface of the element layer was scraped off so that the end of the long part of the carbon nanotube was not exposed.

(Charging element A3)
In producing the charging element A3, as in the case of producing the charging elements A1a to A1c, using the element layer coating liquid A, the element layer coating liquid A has a length of 330 mm, On a conductive substrate made of SUS304 having a width of 11 mm and a thickness of 0.1 mm, coating was performed so that the length was 320 mm, the width was 5 mm, and the thickness was 0.1 mm. Then, the element layer coating liquid A was cured at 130 ° C. for 3 hours without applying an electric field between the conductive substrate and the charging element, and then cured in this way. The surface of the element layer was uniformly shaved in the range of several microns with a microtome to produce a charging element A3.

(Charging element A4)
In manufacturing the charging element A4, similarly to the case of manufacturing the charging elements A1a to A1c, using the element layer coating liquid A, the element layer coating liquid A has a length of 330 mm, The element layer coating liquid A is applied to a length of 320 mm, a width of 2 mm, and a thickness of 0.1 mm on a conductive substrate made of SUS304 having a width of 11 mm and a thickness of 0.1 mm. did. Then, the element layer coating liquid A was cured at 130 ° C. for 3 hours so that an electric field was not applied between the conductive substrate and the charging element, thereby producing a charging element A4. Further, in this charging element A4, the operation of scraping the surface of the element layer to expose the end of the long part of the carbon nanotube was not performed.

(Charging element B)
In manufacturing the charging element B, a multi-walled carbon nanotube having a diameter of 10 to 40 nm, a length of a long portion of 1 to 10 μm, and a carbon purity of more than 95% is used. % Of multi-walled CNT high content dispersion Epicoat 828 paste (manufactured by Meijo Nanocarbon Co., Ltd .: MWNT M-10H) was added to 95 parts by weight of 2-ethyl-4-methylimidazole (2E4MZ), This was mixed and stirred at 60 ° C. for 15 minutes by an emulsifier to obtain a coating liquid B for element layer.

  On the conductive substrate made of SUS304 having a length of 330 mm, a width of 11 mm, and a thickness of 0.1 mm, the element layer coating liquid B is 320 mm in length, 5 mm in width, and 0 mm in thickness. It was applied so as to be 1 mm.

  Next, without applying an electric field between the conductive substrate and the charging element, the element layer coating liquid B was cured at 110 ° C. for 1 hour to produce a charging element B. In the charging element B as well, the operation of scraping the surface of the element layer to expose the ends of the long portions of the carbon nanotubes was not performed.

  Here, in the charging elements A1a to A1c, the charging elements A2 to A4, and the charging element B manufactured as described above, the carbon nanotube (CNT) content (wt%) in the element layer is As shown in Table 1 below, the charging elements A1a to A1c and the charging elements A2 to A4 were 1 wt%, and the charging element B was 9.5 wt%.

  For the charging elements A1a to A1c, charging elements A2 to A4 and charging element B manufactured as described above, each element layer was cut with a microtome, and a field emission transmission electron microscope (Hitachi High-Technologies Corporation). Based on a TEM image using HF-3300), the dispersibility and orientation of the carbon nanotubes were examined, and the results are shown in Table 1 below. Here, with respect to dispersibility, the case where no aggregates of carbon nanotubes were confirmed in 10 TEM images was 1, and the case where there were 3 or less aggregates of carbon nanotubes confirmed in 10 TEM images. Was evaluated as 3 when the number of aggregates of carbon nanotubes confirmed in 2 or 10 TEM images was 10 or less, and the orientation of carbon nanotubes was evaluated for the presence or absence of orientation.

  For the charging elements A1a to A1c, charging elements A2 to A4, and charging element B manufactured as described above, the surface of the element layer on the side opposite to the conductive substrate was subjected to a field emission scanning electron microscope (Hitachi Observed by Technologies, Inc .: SU8020), it was examined whether the end of the long part of the carbon nanotube was exposed on the surface of the element layer, and the results are shown in Table 1 below.

  As a result, the charging element B having a high carbon nanotube content of 9.5 wt% in the element layer is different from the charging elements A1a to A1c and charging elements A2 to A4 in which the carbon nanotube content is 1 wt%. In comparison, the aggregation of carbon nanotubes increased and the dispersibility deteriorated.

  Further, when the charging elements A1a to A1c and the charging elements A2 to A4 are compared, the element layer coating liquid is cured while applying an electric field between the conductive substrate and the charging element to obtain the element layer. The elements A1a to A1c and the charging element A2 have a carbon nanotube dispersibility and orientation compared to the charging elements A3 and A4 obtained by curing the element layer coating liquid without applying an electric field. It was even better.

  Further, in the charging elements A1a to A1c and the charging element A3 in which the surface of the cured element layer is uniformly scraped within a range of several microns, the end portion of the long part of the carbon nanotube is formed on the surface of the element layer. In the charging elements A2 and A4 and the charging element B in which the surface of the element layer was not removed, the end portions of the long portions of the carbon nanotubes were not exposed on the surface of the element layer. It was.

  Next, a drum cartridge used in a commercially available copying machine (manufactured by Konica Minolta: Bizhub 554e) is remodeled, and the charging characteristics in the image carrier and the generation state of ozone are determined using the charging device in the embodiment of the present invention. I tried to check.

  Here, in each of the charging devices of Examples 1 to 7, as shown in Table 2 below, the charging elements A1a to A1c, the charging elements A2 to A4, and the charging element B are used, and the extraction electrode is used. For example, a grid electrode made of SUS304 having a mesh wire diameter of 0.1 mm and a mesh wire distance of 1 mm used in the copying machine is used.

  In the charging devices of Examples 1 to 7, the distance d1 (mm) between the conductive substrate and the extraction electrode in each of the charging elements, and the distance d2 between the extraction electrode and the surface of the image carrier ( mm) is set as shown in Table 2 below, and charging is performed so that the surface potential Vo of the image carrier becomes −500 V ± 5 V in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 60 ± 5%. The extraction voltage (Vex) to be applied to the extraction electrode and the charging element current (Iem) in each charging element were determined, and the results are shown in Table 2 below.

  Further, each of the charging devices of Examples 1 to 7 was used in the copying machine, and a halftone image having a B / W ratio of 10% was obtained in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 60 ± 5%. Continuous printing was performed, and the average concentration of ozone for 10 minutes after 30 minutes from the start of operation was measured with an ozone densitometer (manufactured by Direc Co., Ltd .: MODEL-1200). The ozone generation amount (ppm) is shown in Table 2 below.

  In Comparative Example 1, the charging element in the above-described embodiment is not provided, and a charging device using only the grid electrode in the copying machine used as the extraction electrode is used.

  Further, as the charging device of Comparative Example 2, the scorotron type charging device used in the copying machine is used as it is.

  Further, as the charging device of Comparative Example 3, a charging roller used in a commercially available copying machine (manufactured by Konica Minolta, Inc .: Bizhub C3850) was used.

  Then, using the charging device of Comparative Examples 1 to 3, charging is performed so that the surface potential Vo of the image carrier becomes −500 V ± 5 V in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 60 ± 5%. In Comparative Example 1, the grid voltage (Vg) applied to the grid electrode is obtained, and in Comparative Example 2, the grid voltage (Vg) applied to the grid electrode and the charging applied to the sawtooth charging electrode. The voltage (Vc) and the charging current (Ic) flowing through the charging electrode were determined. In Comparative Example 3, the charging voltage (Vc) applied to the charging roller was determined. The results are shown in Table 3 below.

  For each of the charging devices of Comparative Examples 1 to 3, the ozone generation amount (ppm) was measured in the same manner as in the charging devices of Examples 1 to 7, and the results are shown in the following table. 3 shown.

  As is apparent from the results of Tables 2 and 3, Example 1 using a charging element in which an element layer in which carbon nanotubes are dispersed in a resin is provided on the surface of a conductive substrate facing the image carrier. Compared with the charging device of Comparative Example 1 using only the grid electrode, the charging device of Comparative Example 2 of the scorotron type, and the charging device of Comparative Example 3 using the charging roller in the charging devices of ˜7. In order to charge the body to a predetermined surface potential, the voltage applied to each of the charging elements can be lowered, and the amount of ozone generated can be reduced.

  Further, when the charging devices of Examples 1 to 7 are compared, in particular, in a state in which the carbon nanotubes are dispersed in the element layer, the elongated portion is oriented toward the surface of the element layer facing the image carrier. In addition, the charging devices of Examples 1 to 3 using the charging elements A1a to A1c in which the end portions of the long portions of the carbon nanotubes are exposed on the surface of the element layer facing the image carrier are provided in the element layer. Even when the amount of carbon nanotubes to be contained was reduced, the voltage applied to the charging element could be lowered to charge the image carrier to a predetermined surface potential.

10: Image forming apparatus 11: Image carrier (charged body)
12: latent image forming device 13: developing device 14: transfer device 15: fixing device 16: cleaning device 20: charging device 21: charging element 21a: conductive substrate 21b: element layer 22: extraction electrode 23: charging power source S : Recording sheet d1: Distance between charging element and extraction electrode d2: Distance between extraction electrode and object to be charged

Claims (10)

  In a charging element that discharges electrons by the action of an electric field to charge the object to be charged, an element layer in which carbon nanotubes are dispersed in resin is provided on the surface of the conductive substrate facing the object to be charged. An element for charging.   2. The charging element according to claim 1, wherein a long part of the carbon nanotube is oriented and dispersed in the resin in the element layer so as to face the charged body. element.   3. The charging device according to claim 1, wherein an end portion of the long portion of the carbon nanotube is exposed on a surface of an element layer facing a member to be charged. element.   Applying a resin in which carbon nanotubes are dispersed on the surface of a conductive substrate, curing the resin while applying an electric field, and providing an element layer in which carbon nanotubes are dispersed in the resin Device manufacturing method.   5. The method of manufacturing a charging element according to claim 4, wherein an electric field is applied so that a long portion of the carbon nanotube is directed to the charged body when the resin in which the carbon nanotube is dispersed is cured. A method for producing a charging element, characterized in that a long portion of the substrate is oriented so as to be directed to a member to be charged.   6. The method for manufacturing a charging element according to claim 4 or 5, wherein after the resin in which carbon nanotubes are dispersed is cured, the surface of the element layer facing the object to be charged is surface-treated. A method for manufacturing a charging element, wherein an end of a long part of a nanotube is exposed on a surface of an element layer facing a member to be charged.   In the manufacturing method of the element for charging according to any one of claims 4 to 6, a thermosetting epoxy resin is used for the resin, and an imidazolium salt is contained in the thermosetting epoxy resin. A method for manufacturing a charging element, characterized in that:   4. The charging device using the charging element according to claim 1, wherein electrons are emitted from the charging element by an action of an electric field between the charging element and a member to be charged. 5. A charging device comprising an extraction electrode to be provided.   9. The charging device according to claim 8, wherein a distance d1 between the charging element and the extraction electrode and a distance d2 between the extraction electrode and the member to be charged satisfy a relationship of d1 ≦ d2. Characteristic charging device.   An image forming apparatus, wherein the surface of the image carrier is charged by the charging device according to claim 8.

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