JP2008216333A - Cleaning member for electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent cleaning member having a prescribed destaticizing effect by itself, then, completely dispensing with the use of a destaticizing mechanism. <P>SOLUTION: Regarding the cleaning member for scraping residual toner by destaticizing the surface of a rotating image carrier in slide contact with the image carrier, a conductive resin film 2 set so as to charge a positive polarity charge by friction with the image carrier is formed on the outer peripheral surface of a base body 1 thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cleaning member for an electrophotographic image forming apparatus for removing toner remaining on the outer peripheral surface of an image carrier such as a photosensitive drum.

  In image formation in an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile, generally, the outer peripheral surface of a photosensitive drum is uniformly charged, and then an original image is formed on the outer peripheral surface as an electrostatic latent image. Toner is attached to the toner to form a toner image and transferred to a sheet. The toner remaining on the outer peripheral surface of the photosensitive drum is scraped and removed by a cleaning member 11 slidably in contact with the outer peripheral surface of the photosensitive drum 10 as shown in FIG. The surface of 10 is neutralized to prepare for the next charging.

  However, in this method, a toner removal mechanism using the cleaning member 11 and a charge removal mechanism using the eraser lamp 12 must be provided, and there is a problem that the cost of the charge removal member such as the eraser lamp 12 is high, and the overall size of the apparatus is small. There is a problem that it becomes an obstacle to weight reduction and weight reduction. In addition, when the eraser lamp 12 is repeatedly irradiated with static elimination light, the surface of the photosensitive drum 10 is deteriorated by light fatigue, charging performance is deteriorated, and image quality is deteriorated.

In view of this, several technologies have been proposed in which the cleaning member 11 is made of a conductive material and a voltage is applied to the cleaning member 11 so that the photosensitive drum 10 is neutralized and the toner is scraped off at the same time, thereby eliminating the neutralization mechanism by the eraser lamp 10. (See Patent Documents 1 and 2).
JP-A-5-265362 Japanese Patent Laid-Open No. 7-113039

  However, even with these techniques, a mechanism for removing electricity by applying a voltage to the cleaning member 11 is necessary. Therefore, it is not possible to sufficiently reduce costs, reduce the overall size of the apparatus, and reduce the weight. . Further, the portion of the cleaning member 11 that is in sliding contact with the photosensitive drum 10 is set so as to be somewhat elastically deformed so as not to damage the outer peripheral surface of the photosensitive drum 10, but in order to give the cleaning member 11 a certain conductivity. When a large amount of conductive material such as metal powder is blended, there is a problem that the elasticity of the cleaning member 11 is impaired and the surface of the photosensitive drum 10 is easily damaged.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an excellent cleaning member that itself has a certain static elimination effect and does not require any static elimination mechanism.

  In order to achieve the above object, the cleaning member for an electrophotographic image forming apparatus of the present invention is a cleaning member for slidingly contacting a rotating image carrier and discharging the surface thereof to scrape residual toner. A conductive resin film set to charge positive charges by friction with the image carrier is formed on at least the surface of the sliding contact portion of the cleaning member.

  That is, the present inventors have hitherto required it to eliminate static electricity using frictional charging that occurs during sliding contact between the cleaning member and the image carrier in the course of intensive research to solve the above-described problems. The idea was that the static neutralization mechanism could be completely eliminated. As a result of further research, if a conductive resin film that charges positive charges by friction with the image carrier is formed on at least the surface of the cleaning member in contact with the image carrier, the above The inventors have found that a positive charge generated at the time of triboelectric charging reduces the potential on the image carrier side, so that an excellent charge eliminating action can be obtained, and the present invention has been achieved.

  As described above, the cleaning member for an electrophotographic image forming apparatus of the present invention has a conductive resin film that is charged with a positive charge by friction with the image carrier at least on the sliding contact portion of the cleaning member. Therefore, the positive charge generated by friction with the image carrier can reduce the electric potential on the image carrier side and obtain an excellent charge eliminating action. Therefore, if this cleaning member is incorporated in an electrophotographic image forming apparatus, a static elimination mechanism for an image carrier such as a photosensitive drum or a cleaning member, which has been necessary in the past, becomes unnecessary, and the entire electrophotographic image forming apparatus can be downsized. , Light weight can be realized.

  In addition, since the conductive resin film is formed only at least on the surface of the sliding contact portion with the image carrier, and the other part is formed of the original material of the cleaning member, the cleaning member has the conductive resin. Even when a relatively high conductivity is imparted to the film, the cleaning member as a whole has an advantage that a certain elasticity can be ensured and there is no possibility of damaging the surface of the image carrier such as a photosensitive drum.

  Of the cleaning members for an electrophotographic image forming apparatus according to the present invention, in particular, the conductive resin film is mainly composed of at least one of a fluororesin, a melamine resin, and an acrylic resin, and is electrically conductive. What is formed of the resin composition containing the agent is suitable because the positive charge generated by friction with the image carrier can be stably obtained in a large amount.

  In addition, the conductive resin film having a thickness of 3 to 7 μm can be suitably used, in particular, without impairing the original elasticity of the cleaning member.

  Next, an embodiment of the present invention will be described.

  FIG. 1 shows an embodiment of the cleaning member for an electrophotographic image forming apparatus of the present invention. This is used for scraping off the toner remaining on the surface of the photosensitive drum of the electrophotographic image forming apparatus, and includes a base body 1 made of a plate-like elastic body and a conductive resin film 2 covering its outer peripheral surface. It consists of 3 is a plate-shaped holder for supporting the cleaning member.

  The material for forming the base body 1 is not particularly limited, but an elastic composition is used so that the surface of the photosensitive drum is not damaged when the residual toner is scraped off by sliding on the surface of the photosensitive drum. Is common. Examples thereof include a composition in which an appropriate additive is blended with polyurethane, silicone resin, fluororesin, fluororubber, ethylene-propylene-diene rubber (EPDM) or the like. Among these, a polyurethane composition is preferable in that it is excellent in mechanical strength, elastic pressure contact property, and the like.

  The polyurethane composition can be usually obtained using a polyisocyanate, a polyol, a curing agent, and a catalyst.

  The polyisocyanate is not particularly limited. For example, 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate ( 2,6-TDI), 3,3'-tolylene-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 2,4-tolylene diisocyanate uretidinedione (2,4 -TDI dimer), 1,5-naphthylene diisocyanate, metaphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (water-added MDI), carbodiimide-modified MDI, orthotoluidine diisocyanate Examples include diisocyanates such as xylene diisocyanate, paraphenylene diisocyanate, and lysine diisocyanate methyl ester, triisocyanates such as triphenylmethane-4,4 ′, 4 ″ -triisocyanate, and polymeric MDI. These may be used alone or in combination of two or more. Of these, MDI is preferred from the viewpoint of wear resistance.

  The polyol used together with the polyisocyanate is not particularly limited. For example, polyester polyol such as polyethylene adipate (PEA), polybutylene adipate (PBA), polyhexylene adipate, polycaprolactone, polyoxytetra Examples thereof include polyether polyols such as methylene glycol and polyoxypropylene glycol. These may be used alone or in combination of two or more. Of these, PBA is preferred because of its excellent wear resistance.

  And as a hardening | curing agent used with the said polyisocyanate and polyol, it is not specifically limited, 1, 4- butanediol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, hexanediol, 1,4-cyclohexane Examples thereof include polyols having a molecular weight of 300 or less such as diol, 1,4-cyclohexanedimethanol, xylene glycol, triethylene glycol, trimethylolpropane, glycerin, pentaerythritol, sorbitol, 1,2,6-hexanetriol. These may be used alone or in combination of two or more.

  The catalyst used together with the polyisocyanate, polyol and curing agent is not particularly limited, and examples thereof include amine compounds such as tertiary amines and organometallic compounds such as organotin compounds.

  In addition to these, various additives such as foaming agents, surfactants, flame retardants, colorants, fillers, plasticizers, stabilizers, mold release agents, and the like are appropriately added to the polyurethane composition. May be.

  Further, as a material for forming the conductive resin film 2 covering the outer peripheral surface of the base body 1, a resin material that charges a positive charge when the conductive resin film 2 and an image carrier such as a photosensitive drum are rubbed. And a resin composition formed by combining a conductive agent is preferably used.

  Examples of the resin material include a fluorine-based resin, a melamine-based resin, an acrylic resin, and the like. Among these, a fluorine-based resin and a melamine-based resin are preferable. Of the fluororesins, it is particularly preferable to use an acrylic-modified fluororesin because of its excellent static elimination effect. These resins are used alone or in combination of two or more.

Moreover, as a conductive agent used with the said resin material, you may use any of an electronic conductive agent and an ionic conductive agent. Examples of the electronic conductive agent include conductive carbon black such as acetylene black, special conductive black (Ketjen black), conductive furnace black (including superconductive and special conductive), graphite, titanic acid potassium, iron _{oxide, c-TiO 2, c-} ZnO, conductive metal oxides such as c-SnO _2, nickel, metal powders such as copper. Examples of the ionic conductive agent include structural charge-specific anions such as quaternary ammonium salts, borates, lithium perchlorate, and potassium perchlorate, and ionic conductive agents such as a surfactant. These conductive agents may be used alone or in combination of two or more.

  And among the said electrically conductive agents, it is suitable to use an electronic electrically conductive agent in the ratio of 10-40 weight part with respect to 100 weight part of resin materials used as a base. Moreover, it is suitable to use an ionic conductive agent in the ratio of 0.1-5.0 weight part with respect to 100 weight part of resin materials used as a base. That is, if the blending ratio of the conductive agent is out of the above range, the balance between the triboelectric charging characteristics and the conductive characteristics may be deteriorated, and a desirable static elimination effect may not be obtained.

  Furthermore, a filler, a stabilizer, an ultraviolet absorber, a dye, a pigment, a flame retardant, an oil, and the like can be appropriately blended with the resin composition as necessary.

  The resin composition is prepared as a coating liquid by dissolving a resin material in an organic solvent and dispersing the conductive agent therein. Examples of the organic solvent include methyl ethyl ketone (MEK), methanol, toluene, isopropyl alcohol, methyl cellosolve, dimethylformamide and the like. These may be used alone or in combination of two or more.

  The cleaning member of the present invention can be manufactured using the above materials, for example, as follows.

  First, using the base body 1 forming material, the base body 1 integrated with the plate-like holder 3 is produced according to a conventional method. Specific examples include a prepolymer method, a semi-one-shot method, a one-shot method, and the like. Among these, the semi-one-shot method is preferably used from the viewpoint of excellent workability.

  For example, when the base body 1 is prepared according to the semi-one shot method using a urethane composition as the base body 1 forming material, first, polyisocyanate and polyol are prepared from the urethane composition, Both are blended at an appropriate blending ratio and reacted under appropriate reaction conditions to prepare a urethane prepolymer (main agent liquid). On the other hand, the polyol, a chain extender, a catalyst and the like are prepared, blended at an appropriate blending ratio, and mixed under an appropriate mixing condition to prepare a curing agent solution. Next, the main agent liquid and the curing agent liquid are mixed at a predetermined ratio, and the obtained mixed liquid is poured into a mold for cleaning member molding in which the plate-like holder 23 is held in a predetermined arrangement. , Reaction cure. And the base body 1 integrated with the plate-shaped holder 3 can be obtained by taking out the obtained hardening body from a metal mold | die (refer FIG. 1).

  Next, the base body 1 is dipped in the forming material for the conductive resin film 2 prepared as the coating liquid, and then pulled up and dried, whereby the conductive resin film 2 having a predetermined thickness is formed on the outer peripheral surface of the base body 1. A cleaning member in which is formed can be obtained.

  The cleaning member thus obtained is formed on the outer peripheral surface of the base body 1 with a conductive resin film 2 that charges positive charges by friction with the photosensitive drum. If incorporated in the image forming apparatus, when the toner is scraped off by the cleaning member, a positive charge is generated between the photosensitive drum and the negative voltage on the surface of the photosensitive drum can be canceled to some extent. The degree of charge removal is not perfect as in the case of using a conventional charge removal mechanism, but a high-quality image can be obtained and there is no practical problem. Therefore, it is not necessary to provide a static elimination mechanism that has been conventionally required, and the entire electrophotographic image forming apparatus can be reduced in size and weight.

  In the conductive resin film 2, the cleaning member is provided very thinly only on the outer peripheral surface of the base body 1, and the base body 1 itself is made of an elastic material inherent to the cleaning member. As a whole member, a certain elasticity is ensured, and there is an advantage that the surface of the photosensitive drum is not damaged.

  In the above example, the conductive resin film 2 is formed on the entire outer peripheral surface of the base body 1. However, the conductive resin film 2 is formed on the surface of the base body 1 at least in a sliding contact portion with the photosensitive drum or the like. If this is the case, the effect of the present invention can be obtained. For example, as shown in FIG. The shape may not be formed on the tip surface. This shape can be obtained by integrally molding the two base bodies 1 from the left and right sides, forming the conductive resin film 2 on the outer peripheral surface, and then cutting it at the center. it can. According to this, two cleaning members can be produced simultaneously, and the production efficiency is good.

  And although the thickness of the said conductive resin film 2 is not specifically limited, Usually, it is suitable to set to 10 micrometers or less, especially 3-7 micrometers. If the thickness is less than 3 μm, it may be difficult to form the conductive resin film 2 uniformly. Conversely, if the thickness exceeds 7 μm, the elasticity of the base body 1 is impaired, and an image of a photosensitive drum or the like is lost. This is because the surface of the carrier may be damaged.

  In addition, the cleaning member of the present invention is not necessarily formed integrally with the plate-like holder 3 as shown in FIG. 1, and may be adhered to the surface of the plate-like holder 3 later. Or you may attach directly to the cleaning member holding | maintenance part of not only the plate-shaped holder 3 but various cleaning apparatuses.

  The cleaning member of the present invention thus obtained can be used in various electrophotographic image forming apparatuses such as so-called copying machines, printers, and fax machines. In particular, since the apparatus can be reduced in size and weight, it is preferably used in a compact type image forming apparatus.

  In addition to the photosensitive drum 10 shown in FIG. 3, examples of the image carrier to which the cleaning member of the present invention is slidably contact include an intermediate transfer belt in a multicolor copying apparatus.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to the following examples.

  First, as shown below, materials for preparing the cleaning members of Examples and Comparative Examples were prepared.

[Plate-shaped holding material]
A flat galvanized steel sheet [250 mm × 30 mm × 2 mm (thickness)] having an acrylic resin layer (thickness 1 μm) formed thereon was prepared.

[Preparation of forming material (polyurethane composition) for base body]
44 parts by weight of polybutylene adipate (N4010, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 56 parts by weight of MDI (Millionate MT, manufactured by Nippon Polyurethane Industry Co., Ltd.) were stirred for 3 hours under a nitrogen gas atmosphere (80 ° C.). 0.0% of the base agent was prepared. On the other hand, 87 parts by weight of polybutylene adipate (N4010, manufactured by Nippon Polyurethane Industry Co., Ltd.), 13 parts by weight of low molecular polyol (14BD / TMP = 60/40), triethylenediamine (manufactured by Sankyo Air Products Co., Ltd.) 100 ppm relative to both Was stirred in an environment of 80 ° C. and 1.3 kPa (absolute pressure) for 2 hours to prepare a curing agent having an OH number of 210. And the said hardening | curing agent was mix | blended in the ratio of 94 weight part with respect to 100 weight part of said main ingredients, and the formation material (liquid polyurethane composition) for base bodies was prepared.

[Preparation of forming material (coating solution) for conductive resin film]
A forming material having a composition shown in Tables 1 to 3 below is prepared. First, a resin material is dissolved in MEK, which is an organic solvent, and the conductive agent is dispersed therein, thereby forming a forming material for a conductive resin film. (Coating solution) was prepared.

In addition, the detail of the forming material used for the composition shown in Table 1-Table 3 is as follows.
* 1: Defender TR230K, manufactured by Dainippon Ink, Inc. * 2: Nikarak MW-30HM, manufactured by Sanwa Chemical Co., Ltd. * 3: Dynator BR106, manufactured by Mitsubishi Rayon * 4: Heimlen Y-258, manufactured by Dainichi Seika Kogyo * 5: Aron GS-30, manufactured by Toa Gosei Co., Ltd. * 6: Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd. * 7: Quaternary ammonium salt represented by the following formula (1)

[Examples 1 to 8, Comparative Examples 1 and 2]
The plate-shaped holder was set in a mold for forming a cleaning member, and the forming material for the base body was filled in the forming space, followed by heat forming (140 ° C. × 30 minutes). Thereby, the base body integrated with the plate-shaped holder was obtained. And this base body with a plate-shaped holder is immersed in the coating liquid which is the forming material for the conductive resin film, and then pulled up and dried, so that the outer peripheral surface of the base body 1 as shown in FIG. A cleaning member on which the conductive resin film 2 was formed was produced.

Then, the obtained cleaning member is incorporated into a conventional electrophotographic copy forming apparatus (LBP2510, manufactured by Canon Inc.) provided with a static elimination mechanism using an eraser lamp (12 in FIG. 3). The copy work was done without functioning. Then, using a surface potential probe (manufactured by TREK), the surface potential (V _o ) on the surface of the photosensitive drum during charging and the surface potential (V _a ) on the surface of the photosensitive drum immediately after cleaning were measured. In this apparatus, the voltage applied to the photosensitive drum is -1100V.

Further, in accordance with the following method, the obtained copied image is evaluated for the presence or absence of a drum period afterimage (ghost phenomenon) and the presence or absence of longitudinal stripes (residual toner scraping failure by the cleaning member), and the surface potential (V _o , V _a ) And the values shown in Tables 1 to 3 below.

[Drum cycle afterimage]
In an environment with a temperature of 15 ° C. and a humidity of 10%, the samples of Examples 1 to 8 and Comparative Examples 1 and 2 were incorporated into an electrophotographic image forming apparatus (LBP2510, manufactured by Canon Inc.), and a drum period afterimage of a halftone image The presence or absence of (ghost phenomenon) was visually observed and evaluated based on the following evaluation criteria.
○ ... No drum cycle afterimage is confirmed.
Δ: Drum cycle afterimage is slightly confirmed.
X: Drum cycle afterimage is confirmed.
XX: Drum cycle afterimage is clearly confirmed.

[Vertical stripes]
In an environment of a temperature of 15 ° C. and a humidity of 10%, the samples of Examples 1 to 8 and Comparative Examples 1 and 2 were incorporated into an electrophotographic image forming apparatus (LBP2510, manufactured by Canon Inc.), and halftone image vertical stripes ( The presence or absence of residual toner scraping failure due to the cleaning member was visually observed and evaluated based on the following evaluation criteria.
○ ... No vertical stripes are observed.
Δ: Vertical streaks are slightly confirmed.
X: Vertical stripes are confirmed.

[Comparative Examples 3 and 4]
In the same manner as in Example 1, a base body with a plate-like holder was produced and used as a cleaning member as it was without forming a conductive resin film. Then, it was incorporated into an electrophotographic image forming apparatus similar to the above, and a copying operation was performed using a charge eliminating mechanism using an eraser lamp (Comparative Example 3). In addition, copying was performed without using a static elimination mechanism with an eraser lamp (Comparative Example 4).

For these examples, the surface potential (V _o ) on the surface of the photosensitive drum during charging and the surface potential (V _a ) on the surface of the photosensitive drum immediately after cleaning were measured in the same manner as described above. Further, in the same manner as described above, the presence or absence of a drum period afterimage (ghost phenomenon) and the presence or absence of vertical stripes (residual toner scraping failure by the cleaning member) of the obtained copy image are evaluated, and the surface potential (V _o , V Along with the value of _a ), it is also shown in Table 3 below.

  From the results shown in Tables 1 to 3, the cleaning members of the examples all cancel the surface potential of the photosensitive drum to some extent even though no static elimination mechanism is used, and a generally good copy image is obtained. You can see that On the other hand, in Comparative Examples 1 and 2, as the resin material of the conductive resin film, the frictional charge is negative and the surface potential of the photosensitive drum is further increased. Further, Comparative Example 3 is a conventional example using a static elimination mechanism using an eraser lamp, and good results have been obtained, but it is not possible to reduce the size and weight of the apparatus. Furthermore, since Comparative Example 4 does not have a conductive resin film and does not use a static elimination mechanism using an eraser lamp, the image is poor and is not practical.

It is a longitudinal cross-sectional view which shows one Example of this invention. It is a longitudinal cross-sectional view which shows the other Example of this invention. It is operation | movement explanatory drawing of the conventional cleaning member.

Explanation of symbols

1 Base body 2 Conductive resin film

Claims (3)

  A cleaning member for slidingly contacting a rotating image carrier and discharging the surface thereof to scrape residual toner, wherein at least the surface of the cleaning member has a positive polarity due to friction with the image carrier. A cleaning member for an electrophotographic image forming apparatus, wherein a conductive resin film set to be charged is formed.   The electrophotographic film according to claim 1, wherein the conductive resin film is formed of a resin composition containing at least one of a fluororesin, a melamine resin, and an acrylic resin as a main component and containing a conductive agent. Type image forming apparatus cleaning member. The cleaning member for an electrophotographic image forming apparatus according to claim 1, wherein the conductive resin film has a thickness of 3 to 7 μm.

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