JPH075749A - Charging member and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] The present invention provides a charging failure due to surface roughness by defining the surface roughness state of a coating layer of a charging member having a coating layer containing no leveling agent on the surface. It is an object of the present invention to provide a charging member that does not generate According to the present invention, in a charging member having a coating layer containing no leveling agent on its surface, the coating layer has a surface roughness (Rz) of 2 μm or less and a maximum height (Rmax) of 4.5.
The charging member is characterized in that it is less than or equal to μm and the average spacing (Sm) between the irregularities is less than or equal to 250 μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member, an electrophotographic apparatus using the same, and a method for manufacturing the charging member.

[0002]

2. Description of the Related Art Contact charging is performed by pressing a charging member against the surface of a member to be charged and applying a voltage (a DC voltage or a superimposed voltage of a DC voltage and an AC voltage) to the charging member.
The surface of the body to be charged is charged to have a predetermined polarity and potential. Such a contact type charging device has, for example, a configuration as shown in FIG. 1. In FIG. 1, reference numeral 1 is a photosensitive drum which is a member to be charged, and a photosensitive layer 1b is formed on a drum carrier 1a. Has been done. 2 is a charging member, and a core metal 2a
Conductive rubber as the elastic layer 2b, and the surface layer 2c
Are formed by coating. 3 is a power source for applying a voltage to the charging member 2, 4 is a laser beam from the exposure device, and the photosensitive layer is neutralized by the imagewise exposure. A developing device 5 develops a transfer image by attaching toner to a portion where the charge is neutralized. The developed transfer image is transferred by the transfer roller 6 onto the transfer paper 7 pressed against the photosensitive drum 1. After the transfer, the photosensitive drum is cleaned of excess toner by the cleaning device 8.

Such a contact type charging device has advantages such as a lower applied voltage and less ozone generation than a non-contact type corona charging device.

However, in the contact type charging device, the charging member comes into contact with the surface of the body to be charged. Therefore, if the vicinity of the contact surface of the charging member is not smooth, discharge may not occur uniformly and charging failure may occur. Further, in general, when a voltage obtained by superimposing an AC voltage on a DC voltage is applied to the charging member, the influence of the surface property of the charging member is reduced, but the vibration of the AC component causes the toner to melt on the photosensitive drum, which is the member to be charged. Adhesion is liable to occur and image defects are likely to occur, so that it may not be usable in a copying machine having a large number of durable sheets.

As a method of manufacturing a charging member for solving such a problem, when a surface layer is formed by coating,
For example, there is a method in which a leveling agent (for example, silicone oil) is mixed in the paint to slow down the drying speed to smooth the surface layer that is the contact surface of the charging member with the photosensitive drum. The oil may bleed out to the surface of the charging member after being left for a long period of time or at a high temperature due to mixing, which is not preferable.

[0006]

The problem to be solved by the present invention is a charging failure that occurs when the surface coating layer contains no leveling agent.

[0007]

The present invention provides a charging member having a coating layer containing no leveling agent on its surface,
The charging member is characterized in that the coating layer has a surface roughness (Rz) of 2 μm or less, a maximum height (Rmax) of 4.5 μm or less, and an average interval (Sm) of irregularities of 250 μm or less.

That is, according to the present invention, the surface of the coating layer of a charging member having a coating layer containing no leveling agent such as silicone oil, an amine salt type surfactant and an alkylamine type surfactant is roughened. By setting the depth state as described above, it is possible to provide the charging member in which the charging failure due to the surface roughness does not occur.

The charging member according to the present invention can be manufactured as follows.

As a condition for forming the coating layer of the charging member by coating the coating material, after coating the coating material, after primary drying in an atmosphere of relative humidity 57% or more and 95% or less and 15 ° C. or more and 50 ° C. or less. , Heat treatment.

By maintaining the relative humidity in the dry atmosphere at 57% or more and 95% or less at the initial drying of the coating material applied to the surface of the charging member, the water vapor pressure becomes high, and the saturated vapor pressure of the solvent in the coating material becomes high. As it approaches, the initial evaporation rate of the solvent slows down, eliminating the surface roughness due to rapid drying, and as a result,
Surface roughness 10-point average roughness (Rz) = 2 μm or less (reference length: 2.5 mm), maximum height (Rmax) = 4.5 μm
Below (reference length: 2.5 mm), the average spacing of the irregularities (Sm
A charging member having (ISO) = 250 μm or less can be obtained. By using the charging member thus obtained, it is possible to uniformly charge the body to be charged.

In the production method of the present invention, when the relative humidity during the primary drying is less than 57%, the drying rate is high,
The values of Rz, Rmax and Sm (ISO) increase, surface roughness increases, and the effect of the present invention cannot be obtained. When the relative humidity exceeds 95%, Rz, Rmax, Sm
Although the value of (ISO) decreases and the effect can be obtained, the primary drying speed becomes too slow, which may cause thickness unevenness due to liquid sagging, which is not preferable.

Regarding the temperature during the primary drying, it is desirable to carry out the drying at 15 ° C. or more and 50 ° C. or less in order to avoid liquid dripping and rapid drying.

After the primary drying (generally, the coating does not drop even if the surface is touched, it is performed for about 15 minutes),
There is no particular need to pay attention to humidity and temperature, and the surface does not become rough even when heated in an oven or the like.

The charging member formed according to the present invention is a member that contacts a member to be charged and charges it to a predetermined polarity and potential, and may have any form such as a roll shape, a brush shape, and a blade shape. The outermost layer that contacts the member to be charged is the coating layer formed by the method of the present invention.

In the present invention, examples of the paint used for forming the coating layer include resins such as polyamide resin, polyurethane resin, fluororesin and polyvinyl alcohol resin, silicone rubber, NBR and EPD.
The main component is rubbers such as M, CR, IR, BR, and hydrin rubber, and a solvent is appropriately added. Further, conductive or insulating fillers and additives may be mixed.

Examples of the solvent used here include ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone and pentanone, aromatic solvents such as toluene and xylene, alcohol solvents such as methanol, ethanol, propanol and butanol, or Ethyl acetate,
Butyl acetate, tetrahydrofuran, water, etc. can be mentioned.

The charging member manufactured by the method of the present invention can be used when charging is performed by applying either a DC voltage or a superimposed voltage of DC voltage and AC voltage.

FIG. 2 shows a schematic structure of a general transfer type electrophotographic apparatus using a drum type photoconductor.

In FIG. 2, reference numeral 11 denotes a drum type photosensitive member as an image bearing member, which is rotationally driven around the shaft 11a in the direction of the arrow at a predetermined peripheral speed. The photosensitive member 11 is uniformly charged at its peripheral surface by a charging unit 12 at a predetermined positive or negative potential in the course of its rotation, and then in the exposure unit 3, an optical image exposure L (slit exposure, slit exposure Laser beam scanning exposure). As a result, electrostatic latent images corresponding to the exposed image are sequentially formed on the peripheral surface of the photoconductor.

The electrostatic latent image is then toner-developed by the developing means 14, and the toner-developed image is rotated by the transfer means 15 between the photoconductor 11 and the transfer means 15 from a paper feeding portion (not shown). The images are sequentially transferred onto the surface of the transfer material P that has been synchronized and fed.

The transfer material P that has undergone the image transfer is separated from the surface of the photoconductor and is introduced into the image fixing means 19 where it is subjected to the image fixing and printed out as a copy.

After the image transfer, the surface of the photoconductor 11 is cleaned by the cleaning means 16 to remove the residual toner after transfer, and is further discharged by the pre-exposure means 7 to be repeatedly used for image formation. It

The charging member according to the present invention is used as the uniform charging means 12 for the photoreceptor 11 and / or the transfer device 5. As an electrophotographic apparatus, a plurality of constituent elements such as the photosensitive member, the developing unit, and the cleaning unit described above are integrally formed as a process cartridge to form an image, and the process cartridge is formed into an image forming apparatus (for example, a copying machine). , Laser beam printer, etc.) may be detachably attached to the main body. For example, at least one of a charging unit, a developing unit, and a cleaning unit is integrally supported together with a photosensitive member to form a cartridge, which is a process cartridge that can be attached to and detached from an apparatus main body, and guide means such as a rail of the image forming apparatus main body is used. It may be detachable. At this time, the process cartridge may be provided with a charging unit and / or a developing unit.

When the electrophotographic apparatus is used as a copying machine or a printer, the light image exposure L is reflected light or transmitted light from an original, or the original is converted into a read signal, and a laser beam is scanned by this signal. , LED array driving, liquid crystal shutter array driving, or the like.

When used as a facsimile printer, the optical image exposure L becomes an exposure for printing the received data. FIG. 3 is a block diagram showing an example of this case.

The controller 111 controls the image reading section 110 and the printer 119. The entire controller 111 is controlled by the CPU 117. The read data from the image reading unit is transmitted to the partner station through the transmission circuit 113. The data received from the partner station is sent to the printer 119 through the receiving circuit 112. Predetermined image data is stored in the image memory. Printer controller 1
18 controls the printer 119. 114 is a telephone.

The image received from the line 115 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 112, and then the CPU 117 performs a decoding process of the image information and sequentially stores it in the image memory 116. Is stored.
When the image of at least one page is stored in the memory 116, the image of that page is recorded. CPU1
Reference numeral 17 reads out one page of image information from the memory 116 and sends the combined one page of image information to the printer controller 118. Printer controller 118
When receiving the image information of one page from the CPU 117, the printer 11 prints the image information of the page.
Control 9

The CPU 117 is receiving the next page during recording by the printer 119.

As described above, the image is received and recorded.

[0031]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 An elastic layer and a coating layer were formed on a core metal made of stainless steel having a diameter of 10 mm by using a compound for the elastic layer and a coating layer coating having the following composition.

Elastic layer compound EPDM 100 parts by weight, zinc oxide 5 parts by weight, higher fatty acid 1 part by weight, conductive carbon black 5 parts by weight,
Paraffin oil 10 parts by weight, sulfur 2 parts by weight, vulcanization accelerator MBT 1 part by weight, vulcanization accelerator TMTD 1.5
Part by weight and 1.5 parts by weight of vulcanization accelerator ZnMDC were mixed for 20 minutes while cooling with a two-roll to prepare a compound.

Coating material for coating layer 100 parts by weight of methylolated nylon (trade name: resin, manufactured by Teikoku Kagaku), 420 parts by weight of methanol, and 150 parts by weight of toluene were mixed and prepared.

First, the above-mentioned compound for elastic layer was applied on a stainless steel cored bar and vulcanized by heating at 150 ° C. for 15 minutes to obtain a rubber roller having an elastic layer with a thickness of 3 mm.
Next, this roller was dipped and coated in the above coating material for coating layer in an atmosphere adjusted to a temperature of 22.5 ° C. and a relative humidity of 70%, followed by primary drying in that atmosphere for 15 minutes, and then at 120 ° C. By heating and drying for 1 hour, a thickness of 10
A coating layer having a thickness of μm was formed. When the surface property of the formed coating layer was measured, Rz = 1.591 μm, Rmax =
It was confirmed that a smooth surface of 4.410 μm and Sm (ISO) = 222 μm was obtained.

The charging member thus obtained was attached to the position of the primary charger of the analog copying machine (NP6030, manufactured by Canon Inc.), and a DC voltage of -1440V was applied.
Image copying was performed on 10,000 sheets under a low temperature and low humidity (15 ° C., 10% RH) environment. Good images were obtained even after copying 10,000 sheets.

Example 2 A charging member was manufactured in the same manner as in Example 1 except that the temperature at the time of applying the coating material for the coating layer and at the time of primary drying was set to 15.0 ° C. As a result, Rz = 1.508 μ
m, Rmax = 4.229 μm, Sm (ISO) = 21
A coating layer having a smooth surface property of 2 μm was formed.

When the charging member thus obtained was evaluated in the same manner as in Example 1, a good image was similarly obtained even after copying 10,000 sheets.

Example 3 A charging member was prepared in the same manner as in Example 1 except that the temperature at the time of applying the coating material for the coating layer and the primary drying was 50.0 ° C. and the relative humidity was 95%. It was made. as a result,
Rz = 1.583 μm, Rmax = 4.381 μm, S
A coating layer having a smooth surface property of m (ISO) = 219 μm was formed.

When the charging member thus obtained was evaluated in the same manner as in Example 1, a good image was similarly obtained even after copying 10,000 sheets.

Example 4 The charging member obtained in Example 1 was attached to the position of the primary charger of an analog copying machine (NP6030, manufactured by Canon Inc.), DC voltage -700V, AC voltage 1.5kV.
(Voltage between peaks) and frequency of 1.2 kHz were superimposed and applied, and 10,000 images were copied under a low temperature and low humidity (15 ° C., 10% RH) environment. Good images were obtained even after copying 10,000 sheets.

Example 5 A charging member was prepared in the same manner as in Example 1 except that the temperature during coating of the coating material for the coating layer and the primary drying was 23 ° C. and the relative humidity was 57%. . As a result, Rz =
1.597 μm, Rmax = 4.487 μm, Sm (I
A coating layer having a smooth surface property of (SO) = 248 μm was formed.

The charging member thus obtained was evaluated in the same manner as in Example 1. As a result, a good image was similarly obtained even after copying 10,000 sheets.

Comparative Example 1 A charging member was manufactured in the same manner as in Example 1 except that the relative humidity at the time of applying the coating material for the coating layer and at the time of primary drying was 55%. As a result, Rz = 2.014μ
m, Rmax = 5.355 μm, Sm (ISO) = 33
A coating layer having a slightly rough surface property of 3 μm was formed.

The charging member thus obtained was evaluated in the same manner as in Example 1. As a result, a slightly rough halftone image due to surface roughness was obtained.

Comparative Example 2 A charging member was prepared in the same manner as in Example 1 except that the relative humidity at the time of applying the coating material for the coating layer and at the time of primary drying was set to 99%. As a result, Rz = 1.496μ
m, Rmax = 4.089 μm, Sm (ISO) = 19
Although the surface property was as good as 1 μm, the coating layer was formed in which liquid dripping was generated at the edge and the thickness was partially varied.

The charging member thus obtained was evaluated in the same manner as in Example 1. As a result, an image having density unevenness in halftone due to thickness variation was obtained.

Comparative Example 3 Preparation of Compound for Elastic Layer Same as in Example 1.

Preparation of coating material for coating layer Same as in Example 1.

Preparation and Evaluation of Charging Member A stainless steel core bar having a diameter of 10 mm was first heated and vulcanized at 150 ° C. for 15 minutes to obtain a rubber roller having an elastic layer having a thickness of 3 mm. Next, this roller is dip-coated in an atmosphere in which the temperature is 22.5 ° C. and the relative humidity is adjusted to 30%, and then 1
After primary drying for 5 minutes and heating and drying at 120 ° C. for 1 hour, the thickness is 10 μm and the surface roughness Rz = 4.716 μ.
m, Rmax = 7.249 μm, Sm (ISO) = 33
A charging member having a covering layer having a surface roughness of 3 μm was obtained.

This charging member is used as an analog copying machine (NP60
30 Installed at the position of the primary charger of Canon Co., Ltd., applied DC voltage -1440V, low temperature, low humidity (15
When an image after 10,000 sheets was output in an environment of 10 ° C. and 10% RH), a rough halftone image was output due to the surface roughness.

[0052]

As described above, according to the present invention, it is possible to provide a charging member having good uniform charging characteristics without using an additive.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an electrophotographic apparatus using a charging member of the present invention.

FIG. 2 is a schematic configuration diagram of a general transfer type electrophotographic apparatus in which the charging member of the present invention is used.

FIG. 3 is a block diagram of a facsimile using the electrophotographic apparatus as a printer.

Claims (4)

[Claims] 1. A charging member having a coating layer containing no leveling agent on the surface thereof, wherein the surface roughness (R
z) is 2 μm or less, maximum height (Rmax) is 4.5 μm
A charging member having the following and an average interval (Sm) of irregularities of 250 μm or less. 2. A process cartridge in which at least a charging member and a photoconductor are integrally formed into a cartridge and which is detachable from the main body of the image forming apparatus, wherein the charging member has a coating layer containing no leveling agent on its surface, The surface roughness (Rz) of the coating layer is 2 μm or less, and the maximum height (Rm)
ax) is 4.5 μm or less and the average spacing of irregularities (Sm)
Is 250 μm or less, a process cartridge. 3. An electrophotographic apparatus having a photoconductor, a latent image forming means, a means for developing the formed latent image, and a means for transferring the developed image to a transfer material, wherein the charging member of the latent image forming means is on the surface. It has a coating layer containing no leveling agent, the surface roughness (Rz) of the coating layer is 2 μm or less, and the maximum height (R
max) is 4.5 μm or less, and the average interval of irregularities (S
m) is 250 μm or less, an electrophotographic apparatus. 4. A method of manufacturing a charging member having a coating layer on the surface thereof, wherein after coating the coating layer with a coating material, an atmosphere having a relative humidity of 57% to 95% and a temperature of 15 ° C. to 50 ° C. The method for manufacturing a charging member is characterized in that the charging member is formed by first heat-drying and then heat treatment.