JP2007098201A - Manufacturing method of electrifying member and manufacturing apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrifying member in which the electrifying member for forming an image of excellent quality can be manufactured by preventing flocculation of particles such as a pigment or a filler in a coating liquid when forming a film of the electrifying member so as to improve uniformity of the coating liquid, and keeping resistance as a conductive coating layer after film-formation constant over a long period of time, and to provide a manufacturing apparatus therefor and the electrifying member manufactured by the method. <P>SOLUTION: In the manufacturing method of the electrifying member for electrifying a latent image holder, the film is formed on a base body by using a dip coating method. The manufacturing method includes: a stirring circulation process of circulating the coating liquid while stirring it with a mill dispersing machine; and a dip coating process of coating the base body by dipping the base body in the coating liquid obtained in the stirring circulation process, wherein the gross value of the coating liquid at 20°C is kept to be 90% or more of initial gross value at 20°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charging member manufacturing apparatus for charging a latent image holding member such as a photosensitive member used in an electrostatic latent image process in a copying machine, a printer, and the like, and more particularly, a charging member used in a continuous circulation type dip coating method. The present invention relates to a manufacturing method and a manufacturing apparatus thereof.

  2. Description of the Related Art Conventionally, as a charging member manufacturing apparatus based on a dip coating method, which is a manufacturing method of a charging member, there is an apparatus including a circulation system that circulates a coating liquid and a charging member lifting device. The circulation system for circulating the coating liquid includes a coating tank that fills the coating liquid, a coating liquid tank, a pump, and piping. The coating liquid is supplied from the coating liquid tank to the coating tank using a pump. The By doing so, the coating liquid more than the capacity of the coating tank is circulated to the coating liquid tank. As a result, the liquid level in the coating tank is kept constant, and a conductive coating layer is formed on the elastic layer by pulling up the base of the charging member immersed in the coating tank of the constant liquid level at a certain speed. Is done. In such a dip coating method, it is necessary to circulate the coating liquid in order to make the coating liquid uniform and prevent defects in the coating film.

  On the other hand, as the coating liquid used for the charging member, a pigment mixed with a resin solution and dispersed, a particulate filler mixed with a resin solution and dispersed, or the like is used. However, when these dispersions are used as the coating liquid, a phenomenon occurs when the coating liquid is circulated in the conventional dip coating apparatus as described above. This is a phenomenon in which particles such as pigments or fillers aggregate, the uniformity of the coating liquid decreases, and separation of the resin component and the pigment component occurs. As a result, a defect occurs in the coating film, and there arises a problem that the image quality of the copying machine or printer is lowered when the obtained charging member is used. Accordingly, it is necessary that the coating liquid used in the dip coating method is always dispersed in a constant state in which pigments, fillers, and the like become fine particles.

Although not a charging member manufacturing apparatus, the following method is known in an electrophotographic photoreceptor manufacturing apparatus that requires a uniform dispersion state of the coating liquid. For example, there are a method of applying a coating liquid while vibrating by ultrasonic dispersion (Patent Document 1), a method of replenishing a coating liquid tank with a coating liquid treated by a sand mill (Patent Document 2), and the like.
Japanese Patent Laid-Open No. 03-62035 JP-A-60-61756

  However, with respect to the electrophotographic photosensitive member, the conventional method has not been sufficient yet. That is, there is a problem that the coating liquid to be circulated cannot be maintained in the uniform dispersion state, and black spots and white spots are still generated and a non-uniform image can be obtained. Further, as a result of studies by the present inventors, since the conventional method relates to an electrophotographic photosensitive member manufacturing apparatus and not a charging member manufacturing apparatus, necessary dispersion as a coating liquid for the charging member is required. The state maintenance was insufficient.

  Accordingly, an object of the present invention is to prevent the aggregation of particles such as pigments or fillers in the coating liquid, to improve the uniformity of the coating liquid, and to increase the resistance value in the conductive coating layer after film formation for a long time. To keep constant over time. It is another object of the present invention to provide a charging member manufacturing method, a manufacturing apparatus, and a charging member made by the method capable of manufacturing a charging member on which an image with excellent image quality is formed.

  As a result of extensive research, the present inventors have succeeded in finding the following method. It relates to a method for manufacturing a charging member in which a conductive coating layer is formed on an elastic layer by a continuous circulation dip coating method. That is, the coating liquid used there is a method of causing aggregation of particles such as pigments or fillers and separation of the coating liquid during circulation so as not to impair the uniformity of the coating liquid. That is, the manufacturing apparatus is provided with a circulating mill disperser whose operation is controlled by the gloss value of the coating liquid. By doing so, a uniform coating solution is maintained during coating, and the resistance value as the conductive coating layer after film formation is kept constant over a long period of time, thereby achieving the object of the present invention.

  Therefore, the method for producing a charging member of the present invention is a method for producing a charging member for charging a latent image holding member by forming a film on a substrate using a dip coating method, and stirring the coating liquid with a mill disperser. And a dip coating step of immersing and applying the substrate in the coating solution obtained in the stirring and circulating step, and the gloss value of the coating solution is The gloss value of 20 ° is maintained at 90% or more of the gloss value of 20 ° of the initial coating liquid.

  The charging member manufacturing apparatus of the present invention includes a coating tank, a tank, and a circulation pump connected by piping, and the charging member manufacturing apparatus forms a film on a substrate by a dip coating method. A circulating mill disperser is disposed between the tank and the tank via a pipe, and the circulating mill disperser has a gloss value of 20 ° of the coating liquid, which is 20 ° of the initial coating liquid. It operates when it falls below 90% of the gross value.

  It is to prevent the agglomeration of particles such as pigments or fillers in the coating liquid and to improve the uniformity of the coating liquid. And a method of manufacturing a charging member that maintains a constant resistance value as a conductive coating layer after the film formation over a long period of time and forms an image with excellent image quality, a manufacturing apparatus thereof, and a charging member made by the method can do.

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

  FIG. 1 is a schematic configuration diagram of a charging member manufacturing apparatus according to the present invention. 1 is a coating tank, 2 is a coating liquid tank, 3 is a coating liquid, 4 is a circulation pump, 5 is a circulating mill disperser, 6 is a coating liquid tray, 7 is an elevator, 8 is a base (charging member) Base layer), 9 is piping.

  In FIG. 1, the base member 8 of the charging member is immersed in the coating solution in the coating tank 1 while being mounted on the holding unit of the elevator 7. The coating liquid overflowing from the coating tank is collected by the coating liquid tray 6 and flows into the coating liquid tank 2. The coating liquid is sent from the coating liquid tank 2 to the circulation mill disperser 5 by the circulation pump 4, and the aggregated pigments and fillers are dispersed by the circulation mill disperser, regenerated into fine particles, and uniformly dispersed. A coating solution is supplied to the coating tank 1. At this time, a filter for removing wear debris such as media used in the processing of the circulating mill disperser 5 and the generated foreign matter may be appropriately provided between the circulating mill disperser 5 and the coating tank 1. Good.

In the present invention, the circulating mill disperser 5 does not need to be operated at all times, monitors the state of the coating liquid, and operates in a timely manner before the aggregation of pigments and fillers and the homogenization of the coating liquid are impaired. do it. The present invention employs the gloss value of the coating liquid as a control index for timely operation. The gloss value of the coating liquid for the charging member changes every moment depending on the dispersion state of the coating liquid, and the gloss value decreases when aggregation or the like occurs. It can be said that the gloss value does not change that the dispersion state is kept constant.
Utilizing this, if coating is performed in a state where the dispersion state is constant, the same resistance value of the obtained charging member can be obtained, and it becomes possible to produce a charging member capable of obtaining a good image over a long period of time. .

  The reflection intensity of gloss value measurement can be measured at several angles (three angles of 20 °, 60 °, and 85 °), but in the present invention, 20 ° is adopted as an appropriate angle that makes it easy to confirm the difference. Yes. Although 20 ° is most suitable for the measurement, it is not necessarily required to be 20 ° in the measurement, and the angle may be changed according to each measurement situation. Further, in the present invention, in consideration of the prescription of the charging member used, the condition for operating the disperser was set as the most suitable case when it was below 90% of the initial gloss value. However, this gloss value varies depending on the performance, resistance value, material configuration, etc. of the target charging member, and can be operated by setting a gloss value suitable for each case. Most preferably, it is less than 90%, but depending on the charging member prescription, for example, the value may be 70%. As a method for measuring the gloss value of the coating liquid, the coating liquid may be sampled at certain intervals, a thin film may be formed using an applicator, and the gloss value may be measured. In addition, a mechanism that can automatically measure the gloss value in the coating liquid tank 2 is installed, and a system that automatically starts / stops the circulating mill disperser 5 based on the measured value is introduced. Good. Furthermore, when the circulating mill disperser 5 is not operated, a bypass may be provided so that the liquid does not need to pass through the disperser.

  In the present invention, the circulating mill disperser 5 is not limited to the one disposed at the position in FIG. 1, and may be disposed at any other position. A plurality of circulating mill dispersers can also be provided.

  Any circulating mill disperser 5 used in the present invention can be used as long as it can disperse the coating liquid by circulation. The mill disperser used in the present invention may be either a vertical type or a horizontal type. The disc shape of the mill disperser can be any plate shape, vertical pin type, horizontal pin type, or the like. As media filled in the mill disperser, small particles made of materials such as alumina, zirconia, stainless steel, glass, sand and iron are used.

  Similar to the setting of the gloss value, the operating disk peripheral speed, media filling ratio, media diameter, operating time, etc. of the circulating mill disperser vary depending on the performance, resistance value, material configuration, etc. of the target charging member, It cannot be set in general. It can be appropriately set so as to obtain a target charging member.

Hereinafter, the present invention will be described in more detail using specific examples. However, the present invention is not limited to these. In addition, "part" in an Example shows a mass part.
(Example 1)
As shown in Fig. 1, the charging member is manufactured by the following procedure using the coating liquid circulating device equipped with a circulating mill disperser and the charging member base layer (elastic layer) lifting and lowering device. did. In addition, as a circulation mill disperser at this time, Ultravisco mill UVM-2 manufactured by AIMEX was used.

  First, the base of the charging member was prepared as follows.

  Epichlorohydrin rubber 100 parts by mass, quaternary ammonium salt 2 parts by mass, calcium carbonate 45 parts by mass, zinc oxide 5 parts by mass, aliphatic polyester plasticizer 8 parts by mass, zinc stearate 1 part by mass, carbon 5 parts by mass of black and the above materials were kneaded for 10 minutes in a closed mixer adjusted to 50 ° C. to prepare a raw material compound. To this compound, 1 part of sulfur as a vulcanizing agent, 1 part of Noxeller DM and 0.5 part of Noxeller TS as a vulcanization accelerator were added to 100 parts of epichlorohydrin rubber as a raw material rubber. And it knead | mixed for 10 minutes with the 2-roll machine cooled to 20 degreeC. The obtained compound was molded by an extruder so as to form a roller around a stainless steel support having a diameter of 6 mm and a length of 252.5 mm, followed by heat vulcanization molding. Thereafter, both ends of the rubber were cut off and polished so as to have an outer diameter of φ8.5 mm to obtain a charging member base (elastic layer) having a length of 230.0 mm.

  Next, a coating solution was prepared as shown below.

  Acrylic polyol solution (Daicel Chemical Industries: Plaxel DC2016) 100 parts by mass, Isocyanate A (IPDI) (Degussa: VESTANAT B1370 active ingredient) 40 parts by mass, Isocyanate B (HDI) (Asahi Kasei Chemicals: DURANATE TPA-B80E ) 30 parts by mass, conductive particles (manufactured by Toda Kogyo Co., Ltd .: CS-Bk100Y), 20 parts by mass, 25 parts by mass of surface-treated titanium oxide (manufactured by Teica Co., Ltd .: SMT-150IB), polymethyl methacrylate (PMMA) average particle size 5 μm resin 20 parts by mass of particles (Sekisui Plastics: Techpolymer MBX-5), 400 parts by mass of methyl isobutyl ketone (main solvent), 0.08 parts by mass of modified dimethyl silicone oil (manufactured by Dow Corning Silicone: SH28PA) Was used to prepare a mixed solution. Subsequently, the mixed solution was subjected to dispersion treatment (treatment speed 500 ml / min) using a circulation type bead mill disperser to prepare a dip coating solution. The initial gloss value of the coating solution at this time was 56.1 at 20 °. The gloss value was measured using a gloss meter (PG-1M) manufactured by Nippon Denshoku Industries Co., Ltd. Using this coating solution, a conductive coating layer having a thickness of 15 μm was formed on the base (elastic layer) of the charging member produced by the above method using the apparatus having the above specifications of the present invention.

  In the circulating mill disperser 5 of the apparatus of the present invention, a small amount of the coating solution was sampled every 2 hours, and a thin film was formed using an applicator. If the gloss value at 20 ° is less than 50.5, which is 90% of the initial value, 80% media filling rate and φ0.8mm glass beads are used as dispersion media, and the disc is rotated at 1200rpm for 20 minutes. It was. The flow rate of the coating liquid at this time was 600 cc / min. In this way, continuous coating of 5000 charging member bases (elastic layers) was performed. When 5,000 continuous coatings were performed, the gloss value of the coating solution was measured, and it showed 53.5 at a gloss value of 20 ° equivalent to the initial coating solution.

In addition, when the resistance value of the 5,000 charging members produced as described above was measured when a 200 V DC current was applied in an atmosphere at a temperature of 23 ° C. and a humidity of 55%, the standard deviation of the resistance value was 7.49E × 10 It was ³ and was good.

  Further, among the obtained charging members, a total of three of the first, 2500th and 5000th ones at the start of coating were mounted on a laser printer. Then, monocolor halftone printing of the initial image was performed in an atmosphere of a temperature of 23 ° C. and a humidity of 55%. The obtained image was visually observed and evaluated. As a result, all the images were excellent in charging uniformity, the image density was the same, and no image defects due to aggregates such as black spots and white spots were observed.

(Comparative Example 1)
In Example 1, the conductive coating layer was charged in the same manner as in Example 1 except that the application was performed without operating the circulating mill disperser in the charging member manufacturing apparatus. 5000 bases (elastic layers) of the member were applied to obtain a charging member.

  When 5,000 continuous coatings were performed in the same manner as in Example 1, the gloss value of the coating solution was measured, and the gloss value was 31.6 at 20 °.

In addition, when the resistance value at the time of applying a 200V DC current was measured in the atmosphere of 23 ° C. and 55% humidity of the 5000 charging members manufactured as described above, the standard deviation of the resistance value was 4.90 × 10 ^5. The resistance value variation was large.

  Furthermore, among the obtained charging members, a total of three of the first, 2500, and 5000th ones at the start of coating are mounted on a laser printer, and the initial image monotonous is at 23 ° C and 55% humidity. Color halftone printing was performed. The obtained image was visually observed and evaluated. As a result, compared with the first image, the 2500th and 5000th images have poor charging uniformity, the image density also changes lightly, and image defects due to aggregates such as black spots and white spots occur. It was. Also, this phenomenon was more noticeable in the 5000th than the 2500th.

(Comparative Example 2)
In Example 1, when the 20 ° gloss value of the thin film produced using the applicator was 39.3 or less, which is 70% of the initial value, glass beads with a media filling rate of 80% and φ0.8 mm were dispersed media. And the disc was rotated at 1200 rpm for 20 minutes. Otherwise, in the same manner as in Example 1, 5000 bases (elastic layers) of the charging member were applied to obtain a charging member.

  When 5,000 continuous coatings were performed in the same manner as in Example 1, the gloss value of the coating solution was measured, and the gloss value was 43.8 at 20 °.

In addition, when the resistance value of the 5,000 charging members manufactured as described above was measured at a temperature of 23 ° C. and a humidity of 55% when a 200 V DC current was applied, the standard deviation of the resistance value was 3.55 × 10 ^4. It was confirmed that the resistance value varied.

  Furthermore, among the obtained charging members, a total of three of the first, 2500, and 5000th ones at the start of coating are mounted on a laser printer, and the initial image monotonous is at 23 ° C and 55% humidity. Color halftone printing was performed. The obtained image was visually observed and evaluated. As a result, the 2500th and 5000th images are inferior to the first image in charging uniformity, the image density also changes lightly, and there are slight image defects due to aggregates such as black spots and white spots. It has occurred. Further, these image defects were generally better in the image of Comparative Example 2 than in Comparative Example 1, but the product was at the NG level.

It is a schematic block diagram of the manufacturing apparatus of the charging member of this invention.

Explanation of symbols

1 Coating tank
2 Coating liquid tank
3 Coating liquid
4 Circulation pump
5 Circulating mill disperser
6 Coating liquid pan
7 Elevator
8 Substrate (base layer of charging member)
9 Piping

Claims (4)

  In a method for producing a charging member for charging a latent image carrier, which forms a film on a substrate using a dip coating method, a stirring and circulating step of circulating a coating liquid while stirring with a mill disperser; and A dip coating step of immersing and coating in the coating liquid obtained in the stirring and circulation step, and the gloss value of the coating liquid is an initial coating liquid having a gloss value of 20 ° of the coating liquid. The method for producing a charging member is characterized by being maintained at 90% or more of the 20 ° gloss value.   2. The method for producing a charging member according to claim 1, wherein the conductive material of the charging member is carbon black.   A charging member obtained by the method for manufacturing a charging member according to claim 1 or 2. In a charging member manufacturing apparatus for forming a film on a substrate by a dip coating method, which is provided with a coating tank, a tank, and a circulation pump connected by piping, a circulating mill dispersion between the coating tank and the tank The circulating mill disperser operates when the 20 ° gloss value of the coating solution falls below 90% of the initial 20 ° gloss value of the coating solution. An apparatus for manufacturing a charging member.