CN112445089A

CN112445089A - Photosensitive drum, image forming apparatus, and method for regenerating photosensitive drum

Info

Publication number: CN112445089A
Application number: CN202010907883.XA
Authority: CN
Inventors: 张军; 外野良太; 千叶裕之; 谷川博哉; 泽田清孝; 菊田航; 田中龙也
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2019-09-02
Filing date: 2020-09-02
Publication date: 2021-03-05
Also published as: JP7375385B2; JP2021039194A; EP3786715A1

Abstract

The invention provides a photosensitive drum which can obtain good characteristics even after being polished, an image forming apparatus having the photosensitive drum, and a photosensitive drum regeneration method. The surface of the protective layer (4) of the photosensitive drum (1) is polished by a polishing device (100) having agglomerated abrasive grains. The arithmetic average roughness Ra of the surface of the protective layer (4) is less than 0.03 [ mu ] m, and the arithmetic average waviness Wa is 0.05 [ mu ] m or more. By reducing the surface roughness at a microscopic level in this manner, the undulation shape of the surface is left at a large level, and thus good characteristics can be obtained even in the case of the photosensitive drum after polishing.

Description

Photosensitive drum, image forming apparatus, and method for regenerating photosensitive drum

Technical Field

The invention relates to a photosensitive drum, an image forming apparatus and a photosensitive drum regeneration method.

Background

In general, in an image forming apparatus, an electrostatic latent image is formed on a photosensitive drum by an optical writing device, the electrostatic latent image is developed into a toner image by a developing device, and the toner image is transferred onto a transfer belt. Then, the toner remaining on the surface of the photosensitive drum is removed by a cleaning device. In this way, by repeating the formation of the toner image and the removal of the toner, damage or the like may occur on the surface of the photosensitive drum.

Then, a photoreceptor recycling device has been proposed in which the surface of a photoreceptor is polished and collected (see, for example, patent document 1). In the photoreceptor recycling device described in patent document 1, the surface roughness Rmax of the photoreceptor after polishing is set to 4.5 μm or less, thereby removing the deposits on the surface of the photoreceptor.

However, the surface roughness of the photoreceptor is merely reduced by polishing, and thus the same characteristics as those of an unused photoreceptor may not be obtained, and further improvement in the characteristics of the photoreceptor after polishing is desired.

The invention aims to provide a photosensitive drum which can obtain good characteristics even after grinding, an image forming device with the photosensitive drum and a photosensitive drum regeneration method.

[ patent document 1 ] Japanese patent application laid-open No. 2002-351098

Disclosure of Invention

In order to solve the above problems, a first aspect of the present invention is a photosensitive drum in which a photosensitive layer and a protective layer are sequentially stacked on an outer peripheral surface of a hollow cylindrical sleeve, the photosensitive drum comprising: in the surface of the protective layer, a surface layer composed of JISB0601:2001 of less than 0.03 μm at a cutoff value of 0.25mm, as defined by JISB0601: the arithmetic mean waviness Wa defined in 2001 is 0.05 μm or more at a cutoff value of 2.5 mm.

According to the photosensitive drum of the present invention, by having the arithmetic average roughness Ra less than 0.03 μm, even if a damage is formed on the surface by using the photosensitive drum, the influence of the damage can be reduced by polishing. Therefore, when the surface of the photosensitive drum is cleaned by the cleaning blade, a cleaning failure due to surface damage can be suppressed, and streak-like contamination or the like due to surface damage can be suppressed at the time of image formation. Further, by setting the arithmetic average waviness Wa to 0.05 μm or more, the cleaning property of the cleaning blade can be secured and one-side contact of the cleaning blade can be suppressed. By reducing the surface roughness at a microscopic level in this manner, the undulation shape of the surface is left at a large level, and thus good characteristics can be obtained even in the case of the photosensitive drum after polishing.

Drawings

Fig. 1 is a cross-sectional view of a photosensitive drum according to an embodiment of the present invention.

Fig. 2 is a sectional view showing a surface state of the photosensitive drum which is not used.

Fig. 3 is a cross-sectional view showing a surface state of the photosensitive drum after use.

Fig. 4(a) and 4(b) are perspective views of a polishing apparatus for polishing the photosensitive drum.

Fig. 5 is a cross-sectional view showing a surface state of the photosensitive drum polished by a polishing mechanism having free abrasive grains.

Fig. 6 is a cross-sectional view showing a surface state of the photosensitive drum polished by a polishing mechanism having fixed abrasive grains.

Fig. 7 is a graph showing the relationship between the primary particles and the average polishing rate when the surface of the photosensitive drum is polished by the polishing mechanism having the agglomerated abrasive grains.

Fig. 8 is a graph showing the arithmetic average waviness Wa of the photosensitive drum before and after polishing.

Fig. 9 is a diagram showing electrostatic capacitances of the photosensitive drums before and after polishing.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in fig. 1, the photosensitive drum 1 of the present embodiment includes a hollow cylindrical sleeve member 2, a photosensitive layer 3 stacked on an outer peripheral surface of the sleeve member 2, and a protective layer 4 stacked on an outer peripheral surface of the photosensitive layer 3. That is, the photosensitive layer 3 and the protective layer 4 are sequentially laminated on the outer peripheral surface of the sleeve member 2. The photosensitive drum 1 is used in an image forming apparatus such as a copying machine, a facsimile machine, a laser printer, and a multifunction peripheral thereof, and an electrostatic latent image is formed on the surface by an optical writing device, the electrostatic latent image is developed into a toner image by a developing device, and the toner image is transferred onto a transfer belt.

The photosensitive layer 3 is composed of, for example, an undercoat layer, a charge generation layer, and a charge transport layer. The protective layer 4 is formed by dispersing a filler such as a resin in a binder resin such as polycarbonate constituting the charge transport layer, for example. The structure and material of the photosensitive layer 3 and the protective layer 4 may be appropriately selected.

Fig. 2 schematically shows the surface shape of the protective layer 4 in the photosensitive drum 1 in an unused state (new product), and fig. 2 schematically shows the surface shape of the protective layer 4 in the photosensitive drum 1 after being used a predetermined number of times.

As shown in fig. 2 and 3 in an enlarged scale (see the dotted line), when the photosensitive drum 1 is used, deterioration of the rough surface occurs due to abrasion or film formation. Further, when the photosensitive drum 1 is used, the damage 41 to 43 is formed due to the contact of one side of the cleaning blade or the developing material. In addition, the surface of the protective layer 4 also has an undulating shape before or after use of the photosensitive drum 1.

As described above, the photosensitive drum 1 deteriorated by use is polished as described below, whereby the photosensitive drum 1 is recycled.

Fig. 4 shows a polishing apparatus (polishing mechanism) 100 for polishing the photosensitive drum 1. The polishing apparatus 100 includes a columnar elastic member 101 and a polishing film 102 attached to the top surface of the elastic member 101, and is configured to be rotated by a power source with the height direction of the columnar elastic member 101 as the axial direction.

The elastic member 101 is made of, for example, foamed polyurethane, foamed EVA sponge, suede, or nonwoven fabric.

The polishing film 102 has aggregated abrasive grains as polishing abrasive grains, and functions as a polishing mechanism. The agglomerated abrasive grains are an agglomerate composed of many fine primary particles, and many primary particles are gradually bonded to each other while forming voids in part to form a granular porous body.

In order to obtain such agglomerated abrasive grains, first, the grains (secondary grains) having a grain size of about 1 to 300 μm are obtained by granulation using a spray dryer. Then, in order to form the structure of the porous body, the particles are subjected to heat treatment. The compression fracture strength of the agglomerated abrasive grains after the heat treatment is preferably 20MPa or less. If the compression fracture strength is too high, scratches are likely to be generated during grinding.

The average particle diameter of the primary particles of the agglomerated abrasive grains is preferably 4 μm or less. The primary particles are preferably inorganic oxides such as alumina, zirconia, silica, ceria, silica, and iron oxide.

Next, the abrasive grains obtained as described above were mixed with a liquid urethane resin, methyl ethyl ketone was added as a solvent to adjust the solution viscosity, and then the mixture was mixed and stirred with a stirrer for about 10 minutes to prepare a mixture. The stirring was carried out at room temperature, and the rotation speed was 100rpm to the extent that the abrasive grains were not broken. The mixture was applied to a base material (for example, a PET film having a thickness of about 75 μm) using a wire bar coater, and then dried in a constant temperature bath maintained at 60 ℃ for 1 hour to obtain a ground film.

The polishing process is performed by rotating the photosensitive drum 1 by a power source, and reciprocating the polishing apparatus 100 in the vertical direction in the figure while rotating it by the power source. At this time, the polishing film 102 rotates together with the elastic member 101 in a state of biting into the surface of the photosensitive drum 1 by a certain amount, and the surface of the photosensitive drum 1 is polished.

The photosensitive drum 1 whose surface of the protective layer 4 has deteriorated by being used a predetermined number of times is subjected to a polishing process by the polishing apparatus 100 as described above to obtain a regenerated photosensitive drum. On the surface of the protective layer 4, the arithmetic average roughness Ra defined by JISB0601:2001 is less than 0.03 μm at a cutoff value of 0.25mm, the arithmetic average waviness Wa defined by JISB0601:2001 is 0.05 μm or more at a cutoff value of 2.5mm, and the maximum height roughness Rz defined by JISB0601:2001 is 0.5 μm or less at a cutoff value of 0.25 mm. In the regenerated photosensitive drum, the average thickness of the protective layer 4 is 0.2 μm or more.

The present embodiment as described above has the following effects. That is, even if the damage 41 to 43 is formed on the surface by using the photosensitive drum 1, the influence of the damage 41 to 43 can be reduced by polishing by setting the arithmetic average roughness Ra in the surface of the protective layer 4 to less than 0.03 μm. When the surface of the photosensitive drum is cleaned by the cleaning blade, a cleaning failure due to surface damage can be suppressed, and streak-like contamination or the like due to surface damage can be suppressed at the time of image formation.

In addition, by making the arithmetic average waviness Wa in the surface of the protective layer 4 0.05 μm or more, the one-side contact of the cleaning blade can be suppressed while the cleaning property of the cleaning blade can be ensured. By reducing the surface roughness at a microscopic level in this manner, the undulation shape of the surface is left at a large level, and thus good characteristics can be obtained even in the case of the photosensitive drum after polishing.

Further, by setting the maximum height roughness Rz in the surface of the protective layer 4 to 0.5 μm or less, new damage due to polishing can be made less likely to occur.

In addition, by making the average thickness of the protective layer 4 0.2 μm or more, it is possible to suppress a change in the electrostatic characteristics of the photosensitive layer 3 and to prolong the service life of the photosensitive drum 1 after regeneration.

By polishing the surface of the protective layer 4 using the polishing film 102 having the agglomerated abrasive grains, the arithmetic average roughness Ra in the surface of the protective layer 4 after polishing can be made less than 0.03 μm, and the arithmetic average waviness Wa can be made 0.05 μm or more.

On the other hand, when polishing is performed using a polishing mechanism (for example, a soft polishing pad such as a nonwoven fabric or a sponge) having free abrasive grains, as shown in fig. 5 (the solid line indicates the surface S0 before polishing, and the broken line indicates the surface S1 after polishing), the waviness can be maintained and the decrease in the arithmetic average waviness Wa can be suppressed, but as polishing progresses, the scratches 41 to 43 also progress, and the scratches deep in the scratches 41 to 43 may not be removed.

In addition, when polishing is performed using a polishing mechanism (e.g., polishing paper) having fixed abrasive grains, as shown in fig. 6, although the scratches 41 to 43 are easily removed, the undulation shape cannot be maintained, and the arithmetic average waviness Wa is reduced.

That is, by polishing with the polishing film 102 having the aggregated abrasive grains as in the present embodiment, the undulation shape can be maintained while removing the scratches 41 to 43.

Further, by using particles having an average primary particle size of 4 μm or less as the agglomerated abrasive grains, it is possible to suppress the occurrence of polishing damage such as scratches on the surface of the protective layer 4, which is the processed surface. On the other hand, if the average particle size of the primary particles is too large, polishing damage such as scratches tends to occur on the processed surface, although the processing efficiency of polishing is improved, and the quality may be deteriorated.

Further, by using the agglomerated abrasive grains having a compressive fracture strength of 20MPa or less, abrasion of the abrasive grains progresses gradually during polishing, a new edge is easily generated, the quality is improved while the processing efficiency is improved when the surface of the protective layer 4 is polished, and further, such a state can be easily maintained for a long time. On the other hand, if the compressive fracture strength of the agglomerated abrasive grains is too high, new polishing damage may be imparted to the surface of the protective layer 4 during polishing, and the surface quality may be degraded.

Further, by using primary particles made of an inorganic oxide as the agglomerated abrasive grains, contamination and damage on the surface of the protective layer 4 can be easily removed.

The present invention is not limited to the above-described embodiments, and includes other configurations and the like that can achieve the object of the present invention, and modifications such as those described below are also included in the present invention.

For example, in the above-described embodiment, the maximum height roughness Rz in the surface of the protective layer 4 is set to 0.5 μm or less in the cutoff value of 0.25mm, but if the arithmetic average roughness Ra is less than 0.03 μm in the cutoff value of 0.25mm, the maximum height roughness Rz may be larger than 0.5 μm.

In the above embodiment, the average thickness of the protective layer is set to 0.2 μm or more, but for example, when the initial image quality is desired to be good, the average thickness of the protective layer may be set to less than 0.2 μm.

In the above embodiment, the average particle diameter of the primary particles is 4 μm or less, the compressive fracture strength is 20MPa or less, and the primary particles are particles made of an inorganic oxide, but the polishing means may have only the aggregated abrasive particles such that the waviness can be maintained by removing scratches on the surface of the protective layer 4, and the average particle diameter, compressive fracture strength, and material of the primary particles may be appropriately selected.

The above-described preferred configurations and methods for carrying out the present invention are not intended to limit the present invention. That is, the present invention is mainly illustrated and described with respect to specific embodiments, and various modifications can be made to the above-described embodiments by those skilled in the art without departing from the technical spirit and the scope of the present invention.

Therefore, the description of the shape, material, and the like disclosed above is only for the purpose of facilitating understanding of the present invention, and is not intended to limit the present invention. The present invention also includes descriptions of names of members excluding some or all of the limitations such as shapes and materials thereof.

[ examples ] A method for producing a compound

[ surface State before and after polishing ]

A polishing film having an average primary particle diameter of 3 μm and a compressive fracture strength of 7.7MPa was used to polish an unused photosensitive drum and a used photosensitive drum, and the arithmetic average roughness Ra and the maximum height roughness Rz before and after polishing were measured. For the measurement, Form Talysurf S4C manufactured by Taylor Hobson was used. In addition, measurements were performed at 4 points (at intervals of 90 °) in the circumferential direction in the surface of the photosensitive drum. The results are shown in Table 1.

TABLE 1

By using the photosensitive drum, both the arithmetic average roughness Ra and the maximum height roughness Rz become large. In both the unused photosensitive drum and the used photosensitive drum, the arithmetic average roughness Ra is reduced by polishing. The maximum height roughness Rz of the unused photosensitive drum becomes somewhat large by the grinding. By polishing the used photosensitive drum, the maximum height roughness Rz becomes small, but is a value larger than that before polishing of the unused photosensitive drum.

[ kind of polishing mechanism and polishing result ]

The surfaces of the used photosensitive drums were polished by the polishing mechanisms of examples 1 to 5 and comparative examples 1 to 3 shown in Table 2.

TABLE 2

The ultra-precision polished film of comparative example 1 was a 1200# film of LAPIKA series manufactured by KOVAX corporation. The ultra-precision polished film of comparative example 2 was a 10000# film of LAPIKA series manufactured by KOVAX corporation, and the grain size was finer than that of comparative example 1. The polishing cloth pad of comparative example 3 was suede-type SURFIN018-3 manufactured by FUJIMI INCORPORATED, and the alumina slurry was obtained by mixing abrasive grains having an average particle diameter of 0.5 μm manufactured by FUJIMI INCORPORATED with water in a weight ratio of 5 wt%. In comparative example 3, alumina slurry was supplied onto the polishing pad at a supply rate of 20cc/min during polishing.

The results of polishing using the polishing mechanisms of examples 1 to 5 and comparative examples 1 to 3 are shown in Table 3.

TABLE 3

In each of examples 1 to 6, the occurrence of new damage due to polishing was suppressed. In particular, in examples 1 to 4, the occurrence of new damage due to polishing can be suppressed. In comparative example 1, new scratches were generated by polishing. In addition, the occurrence of new lesions was evaluated visually.

In each of examples 1 to 6, the damage generated can be removed by using the photosensitive drum. In both comparative examples 2 and 3, the damage generated could not be removed by using the photosensitive drum.

That is, in any of examples 1 to 6, both suppression of generation of new damage by polishing and removal of damage generated by using a photosensitive drum can be achieved, but in comparative examples 1 to 3, both can not be achieved. In any of examples 1 to 6, the arithmetic average roughness Ra was less than 0.03 μm at a cutoff value of 0.25mm, and the arithmetic average waviness Wa was 0.05 μm or more at a cutoff value of 2.5 mm.

The maximum height roughness Rz when the unused photosensitive drums were polished by the polishing mechanisms of examples 1 to 6 is shown in table 4.

TABLE 4

	Rz(μm)
		Example 1	0.25～0.35
Example 2	0.33～0.48
		Example 3	0.25～0.35
Example 4	0.33～0.48
		Example 5	0.6～0.11
Example 6	0.8～1.5

It is seen that the larger the average particle diameter of the primary particles, the larger the maximum height roughness Rz, the larger the compressive fracture strength, and the larger the maximum height roughness Rz.

[ average particle diameter and grinding efficiency ]

The compressive fracture strength was set to be substantially constant (8Mpa), and the average polishing rate (polishing efficiency) when polishing was performed using polishing means in which the average particle diameters of primary particles were different was evaluated. The results are shown in FIG. 7. The larger the average particle size of the primary particles is, the higher the polishing efficiency is, and when the average particle size is 3 μm or more, a good polishing efficiency is obtained.

[ variation in arithmetic mean waviness due to grinding ]

The used photosensitive drum was polished using the polishing mechanism of example 3, and the arithmetic average waviness Wa before and after polishing (before and after regeneration) was measured. The results are shown in FIG. 8. In each sample, the arithmetic average waviness Wa becomes small by grinding, and reaches 0.05 μm or more even after grinding.

[ thickness of protective layer after polishing ]

The used photoreceptor drum was polished by the polishing mechanism of example 3, and the average thickness of the protective layer was 0.2 μm. When the photosensitive drum thus polished was incorporated into an image forming apparatus and a life test was performed, good results were obtained.

[ change in electrostatic capacitance due to polishing ]

The used photosensitive drum was polished by the polishing mechanism of example 3, and the electrostatic capacitance of the surface of the photosensitive drum 1 was measured before and after polishing. The results are shown in FIG. 9. The electrostatic capacitance was decreased by polishing, but no change was observed to affect the quality.

Claims

1. A photosensitive drum in which a photosensitive layer and a protective layer are sequentially laminated on an outer peripheral surface of a hollow cylindrical sleeve, characterized in that:

the surface of the protective layer has an arithmetic average roughness Ra of less than 0.03 [ mu ] m at a cutoff value of 0.25mm and an arithmetic average waviness Wa of 0.05 [ mu ] m or more at a cutoff value of 2.5 mm.

2. The photosensitive drum according to claim 1, wherein:

on the surface of the protective layer, the maximum height roughness Rz is 0.5 [ mu ] m or less at a cutoff value of 0.25 mm.

3. The photosensitive drum according to claim 1 or 2, wherein:

the protective layer has an average thickness of 0.2 [ mu ] m or more.

4. An image forming apparatus, characterized in that:

the photosensitive drum according to any one of claims 1 to 3.

5. A photosensitive drum regenerating method of producing the photosensitive drum according to any one of claims 1 to 3 by applying a polishing process to a used photosensitive drum, characterized in that:

in the polishing process, a polishing mechanism having agglomerated abrasive grains is used as the abrasive grains to polish the surface of the protective layer.

6. The photosensitive drum regenerating method according to claim 5, characterized in that:

as the agglomerated abrasive grains, those having an average primary particle diameter of 4 μm or less and a compressive fracture strength of 20MPa or less are used.

7. The photosensitive drum regenerating method according to claim 5 or 6, wherein:

as the agglomerated abrasive grains, those having primary particles made of an inorganic oxide are used.