JPH0445830B2 - - Google Patents

Description

[Detailed Description of the Invention] [Detailed Description of the Invention] The present invention relates to a cleaning device for the surface of an electrophotographic photoreceptor, and more specifically, the present invention relates to a cleaning device for cleaning the surface of an electrophotographic photoreceptor, and more specifically, it cleans toner remaining on the surface of the photoreceptor after toner image transfer. The present invention relates to a cleaning device that can effectively remove surfaces from surfaces without damaging them.

In electrophotography, as shown in FIG. 1, an electrostatic latent image is formed by charging the surface of a photoconductive photoreceptor 1 with a charger 11 and exposing it to image light through an optical system 12. The latent image is developed with toner 14 by a developing mechanism 13, and the formed toner image is electrostatically transferred onto copy paper 15 by a charger 16. After the transfer, the toner remaining on the surface of the photoreceptor is removed by a charger 17 if necessary. Copying is performed by repeating a series of removal steps by the cleaning mechanism 2. After the transfer process, some of the toner remaining on the photoreceptor surface is electrostatically attracted to the photoreceptor surface, and it is not necessarily easy to remove it by cleaning.

Conventionally, methods such as the fur brush method, method using an elastic blade, and method using a magnetic brush have been used for toner cleaning, but the fur brush method has the problem of toner scattering, and the magnetic brush method requires expensive magnet-contained cleaning. A separate sleeve is required, and if the developing sleeve is also used for cleaning, there is a problem that the cleaning operation lengthens the copying cycle. The method of cleaning by rubbing an elastic blade against the surface of the photoreceptor has the advantage of a simple mechanism and operation, but it overcomes the electrostatic attraction force of the toner particles to the surface of the photoreceptor and exposes the toner particles to the photoreceptor. In order to remove it from the body surface, it is necessary to apply a fairly large pressing force or pressurization force to the tip of the blade, which may damage the photoreceptor surface or shorten the life of the photoreceptor. There is.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cleaning device that can effectively remove toner particles remaining on the surface of a photoreceptor after toner image transfer without damaging the surface of the photoreceptor.

Another object of the present invention is to suppress the frictional force between the elastic blade and the photoreceptor surface during cleaning to a significantly small level, suppress the occurrence of scratches on the photoreceptor surface, and significantly extend the life of the photoreceptor. We are here to provide you with the cleaning equipment you need.

Still another object of the present invention is to provide a cleaning device that effectively reduces the frictional force with the surface of a photoreceptor without substantially changing the rubber elasticity, flexibility, and mechanical properties of the elastic blade. .

Still another object of the present invention is to provide an electrophotographic photoreceptor cleaning device that is extremely simple to operate and has the above-mentioned improvements.

According to the present invention, in an electrophotographic cleaning device having an elastic blade whose tip is provided in contact with the surface of a movable electrophotographic photoreceptor in order to remove toner from the surface of the electrophotographic photoreceptor, the elastic member The blade is made of polyurethane elastomer and has number average primary particles held embedded in the surface of the blade that contacts the photoreceptor surface.
It has spherical particles of polyvinylidene fluoride with a size of 0.1 to 1 μm, and during a run-in operation in which the surface of the movable electrophotographic photoreceptor and the tip of the elastic blade are engaged, the particles are formed at the engagement interface between the two. Provided is an electrophotographic cleaning device characterized in that the cleaning device is embedded in the surface of an elastic blade by supplying an elastic material.

The invention will be explained in detail below with reference to the accompanying drawings.

In FIGS. 1 and 2 showing the schematic arrangement of the cleaning device of the present invention, a cleaning device generally designated by 2 is provided along the path of movement of the movable photosensitive drum 1. As shown in FIG. This cleaning device 2 has an elastic blade 3, which is held at its base by a holder 5 so that its tip 4 makes light sliding contact with the surface of the drum 1.

The elastic blade 3 used in the present invention has a layer 6 of fine spherical particles of polyvinylidene fluoride, which will be described in detail below, on the surface that contacts the surface of the photoreceptor 1 (hereinafter sometimes referred to as the effective surface). In this layer 6, as shown in the enlarged view of FIG. 3, fine spherical particles of vinylidene fluoride or its secondary particles 8 are embedded in the elastic phase 7 constituting the blade 3. A distinctive feature is that it is held uniformly on the surface. The presence of this polyvinylidene fluoride layer 6 is not necessarily confirmed with the naked eye, but when the effective surface of the blade 3 is observed under a microscope, the presence of the structure shown in FIG. 3 can be easily confirmed.

In this surface layer 6, the fact that the polyvinylidene fluoride particles are embedded in the surface of the elastic body means that even if this surface layer is rubbed with a cloth, the polyvinylidene fluoride does not peel off, and the structure shown in FIG. 3 is maintained. This can be confirmed by the fact that the polyvinylidene fluoride particles are retained on the surface, that is, a portion of the particles are exposed on the surface. This can be confirmed from the fact that it is greatly reduced due to the presence of the buried layer.

It is well known that fluorine-based resins have extremely low coefficients of friction and are useful as solid sliding materials for pairings and the like. However, in the present invention, polyvinylidene fluoride is used in the form of fine spherical particles or secondary particles of polyvinylidene fluoride, and these spherical particles or secondary particles are used on the effective surface of the elastic blade. It is important that it is retained in a form that is embedded in it. That is, it is believed that the spherical particles of vinyldene polyfluoride impart colloidal slipperiness to the interface between the elastic blade and the surface of the photoreceptor, and this means that in the elastic blade of the present invention, the entire surface of the blade is made of polyfluoride. This agrees well with the fact that even though the blade surface is not completely covered with vinylidene fluoride, that is, the polyvinylidene fluoride particles exist in a dispersed form, the friction with the photoreceptor surface is significantly reduced. . Moreover, when the entire surface of the elastic blade is coated with a fluororesin film or the like, the hardness of the blade surface increases, which causes a secondary drawback of scratching the photoreceptor during cleaning. The effective surface of the elastic blade of the present invention includes:
Because the fine spherical particles of polyvinylidene fluoride or its secondary particles exist in a dispersed state, the surface of the elastic blade maintains the original flexibility and cushioning properties of the elastic material, and the surface hardness, etc. The occurrence of scratches caused by this will be eliminated. Furthermore,
These spherical particles of fluororesin or their secondary particles are held embedded in the surface of the elastic blade, so even when used for cleaning over a long period of time, they do not come off from the surface. A stable friction-reducing effect can be obtained over a long period of time. This surface retention is stable even when the tip of the elastic blade gradually wears out, so that once the inventive treatment is carried out, the above-mentioned advantages will be achieved throughout the life of the elastic blade. .

In the present invention, in order to form the layer 6 of polyvinylidene fluoride particles on the effective surface of the elastic blade 3, during a running operation in which the surface of the movable electrophotographic photoreceptor and the tip of the elastic blade are engaged, An operation is advantageously used in which the particles are supplied to the engagement interface between the two, thereby embedding the secondary particles of the polyvinylidene fluoride spherical particles or paper on the surface of the elastic blade.

In FIG. 4 for explaining this operation, the tip 4 of the elastic blade 3 is pressed against the photosensitive drum 1, and the photosensitive drum 1 is rotated in the direction of the arrow.
When polyvinylidene fluoride powder is supplied upstream of this contact position, a pool 9 of the powder is formed at the tip 4. A shearing force is applied to the powder in the reservoir 9 due to the relative movement between the tip 4 and the drum 1, so the powder is broken into the shape of a primary sphere or its secondary particles and crushed. The particles are bitten into the contact interface between the blade tip 4 and the drum 1, and are embedded in the surface of the elastic blade. This running-in operation is generally performed by rotating the drum 10 to 500 times.
The polyvinylidene fluoride can be supplied, for example, by sprinkling it on the surface of the photoreceptor, or adding it to the toner in advance. Further, it goes without saying that this run-in operation may be performed not only for the copying machine that actually incorporates the cleaning device, but also for the elastic blade that is incorporated into the copying machine.

The spherical particles of polyvinylidene fluoride used in the present invention can generally be obtained as a powder by emulsion polymerization. These spherical particles have a perfect circular shape when observed using an electron microscope, and their primary particle size (number average particle size based on electron micrographs) is in the range of 0.1 to 1μ.
It generally exists in the form of secondary particles of 1 to 7 microns. The most suitable polyvinylidene fluoride spherical particles for the purposes of this invention are those commercially available under the trade name KYNAR (trademark of Pennwalt Corporation).

Particular preference is given to using elastic blades made of polyurethane elastomer. As the polyurethane elastomer, polyurethane rubbers conventionally used in this field, generally polyurethanes consisting of soft segments derived from polyester polyols or polyether polyols and hard segments derived from aromatic diisocyanates, are used.

The dimensions of the elastic blade are not particularly limited, but the blade length is 15 to 30 mm and the thickness is 0.5 to 5 mm.
mm are advantageously used.

The amount of polyvinylidene fluoride to be applied to the tip of the blade may be such that it is embedded in the effective surface as shown in FIG. 3, and it is difficult to define it unconditionally because it may be an extremely small amount. Generally, it is advisable to set an appropriate amount within the range of 0.0001 to 10 mg per 300 mm width of the blade.

Example 1 An organic photoreceptor drum was produced according to the following procedure.

Poly-N-vinyl cowbazole 100 parts by weight Perylene pigment (Red BL manufactured by Hoechst) 8 parts by weight 2,3-dichloro-1,4-naphthoquinone 20 parts by weight Phenanthrene 40 parts by weight Polyester resin (Toyobo KK) 10 parts by weight Tetrahydrofuran 100 parts by weight The above weighed reagents were placed in a stainless steel ball mill and dispersed for one day to obtain a drum photosensitive liquid.
Next, this photosensitive liquid was coated on the surface of an aluminum drum according to the blade coating method and heated to 100°C.
The drum was dried for 1 hour to produce a photosensitive drum having a photosensitive layer having a thickness of 10 μm. Next, using this drum, a blade test was conducted according to the following procedure.

The above drum is attached to the Sanda Kogyo KK PPC copier DC-
162, and a urethane rubber cleaning blade was pressed onto the drum surface.

Next, fine powder of polyvinylidene fluoride (trade name Kynar, manufactured by Pennwalt Corporation) was uniformly sprinkled on the drum surface, and the drum was rotated 20 times as a run-in operation. was embedded in the pressure welding part of the urethane rubber blade.

As a confirmation test, we observed the pressure contact area between the urethane rubber blade and the drum using a microscope.
Polyvinylidene fluoride fine powder is embedded in the surface of the urethane rubber blade.
Even when the surface of the urethane rubber was rubbed with gauze, the embedded polyvinylidene fluoride fine powder did not come off.

Next, as an abrasion resistance test, a 5000 cycle copying test was carried out, and then the surface of the drum was observed. As a result, there were almost no scratches caused by the blade on the drum surface, and there was no significant difference from the surface of an unused drum.

Comparative Example 1 A drum was produced in the same manner as in Example 1.

Next, we made a PPC copy of this drum made by Sanda Kogyo KK.
It was attached to DC-162 and a urethane rubber cleaning blade was pressed onto the drum surface.

Next, we conducted a 5,000-cycle copying test as a wear-resistance test, but scratches from the blade became noticeable after about 5,000 cycles, and the 5,000-cycle test was not completed.

Example 2 Fine powder of polyvinylidene fluoride (manufactured by Kynar) was uniformly sprinkled on the surface of a selenium photosensitive drum, and the drum was installed in a DC-191 manufactured by Sanda Kogyo KK, which uses a urethane rubber blade as a cleaning method, and the drum was run-in as a running-in operation. The drum was rotated 20 times, and the polyvinylidene powder that was sprinkled on the surface of the drum was embedded in the press area of the urethane rubber blade.

As a confirmation test, we observed the pressure contact area between the urethane rubber blade and the drum under a microscope, and found that fine vinylidene polyfluoride powder was embedded in the surface of the urethane rubber blade, and even when the surface of the urethane rubber was rubbed with gauze, The embedded polyvinylidene fluoride fine powder did not come off.

Next, we conducted a 100,000 copy test to test the scratch resistance, but no scratches appeared on the images.

Comparative Example 2 A test was conducted in the same manner as in Example 2 except that the surface of the selenium photosensitive drum was not sprinkled with polyvinylidene fluoride fine powder.

As a result, after about 50,000 copies, streaks due to drum scratches appeared in the halftone image, and after 100,000 copies, the image quality became noticeably blurred due to the drum scratches.

[Brief explanation of drawings]

FIG. 1 is a schematic layout diagram of an electrophotographic copying machine equipped with the cleaning device of the present invention, and FIG.
FIG. 3 is a partially cutaway side view showing the cleaning device of FIG. 1 in a state in which polyvinylidene fluoride powder is applied, and FIG. 3 is a perspective view showing the effective surface of the elastic blade enlarged on a microscopic scale. , FIG. 4 is an explanatory diagram of a method for forming a polyvinylidene fluoride layer of a cleaning blade of the present invention. The reference number 1 is the photoreceptor, 2 is the cleaning device,
3 is an elastic blade, 4 is a tip, 6 is a layer of polyvinylidene fluoride particles, 7 is an elastic phase, and 8 is a polyvinylidene fluoride particle.

Claims (1)

[Scope of Claims] 1. An electrophotographic cleaning device having an elastic blade whose tip is in contact with the surface of a movable electrophotographic photoreceptor in order to remove toner from the surface of the photoreceptor, comprising: The body blade is made of polyurethane elastomer and has a layer of spherical particles of polyvinylidene fluoride having number average primary particles of 0.1 to 1 μm held embedded in the surface of the blade in contact with the photoreceptor surface, The spherical particles are embedded in the surface of the elastic blade by supplying the particles to the engagement interface between the surface of the movable electrophotographic photoreceptor and the tip of the elastic blade during a run-in operation in which the surface of the movable electrophotographic photoreceptor and the tip of the elastic blade are engaged. 1. A cleaning device for electrophotography, characterized in that: