JPH08262945A - Image forming method - Google Patents

Abstract

PURPOSE: To stably obtain a high-quality image by removing toner remaining on a photoreceptor by using a cleaning device carrying a specified toner guide roller(guide roller). CONSTITUTION: In the cleaning device 24, the guide roller 31 at least having a continuous-pore porous body on its surface is assembled in a cleaning case 25 attached to the frame member 33 of a roller supporting unit 30 and is rotated counterclockwise by coming in contact with the periphery of the photoreceptor drum 20 and following the drum 20. The ASKER C hardness of the roller 31 is 15 to 30, and the roller 31 is constituted of the continuous-pore porous body in a state where the pares are closed. The roller 31 is press-contacted with the drum 20 so as to follow to rotate or forcibly rotate, and adhesively carries the toner scraped by a cleaning blade 26 press-contacted with and separated from the drum 20 by a cam 27 and provided on the downstream side of the roller 31. Then, the toner is peeled by a scraper 32 and fed to a recovering member 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming method characterized by a cleaning means carrying a toner recovery guide roller.

[0002]

2. Description of the Related Art Conventionally, in the electrophotographic method based on the Carlson method, a uniform charge is applied to the surface of an image forming body, imagewise exposure is performed to form an electrostatic latent image, and the latent image is developed to form a toner. An image is formed, and the toner image is transferred and fixed on a transfer material to form an image.

The image-formed body after transfer is cleaned by a cleaning means such as a cleaning blade, a fur brush, a magnetic brush or the like, and is repeatedly used for a long period of time. Here, in the cleaning step, the function of efficiently scraping and cleaning the residual toner on the image forming body by the cleaning means and the function of smoothly collecting the cleaned toner to the outside of the image forming area are essential. Good cleaning is achieved by fully performing the two functions.

[0004]

By the way, according to many years of research conducted by the present inventors, a toner guide roller for collecting toner (simply referred to as a guide roller) has the following unique features in order to sufficiently exhibit its function. Conditions: (1) Durability of the guide roller itself is high, mechanical abrasion resistance is strong, and it is strong against the action of discharge active species such as ozone because it is relatively close to the corona discharge range. (2) Image formation The toner scraped from the body adheres to the surface of the guide roller and can be transported smoothly, and it has excellent transportability and separates the adhered toner from the guide roller in order to smoothly collect the adhered toner by the scraper. (3) The surface of the image forming body should not be worn and damaged when the guide roller is rotated. (4) The surface of the image forming body should have appropriate flexibility, (5) It has a function to remove the paper dust adhering in the transfer step, and it is collected without agglomeration. And other conditions are required.

In particular, in an image forming method employing a toner recycling system in which toner that has not been transferred and remains on the photoconductor is recovered by a cleaning means, and the recovered toner is returned to a developing device or a toner replenishing device for reuse.
When the aggregated toner adhering to the surface of the guide roller is recovered when the condition (6) does not go as set, problems such as toner fireflies and image fogging occur.

The guide roller made of continuous pore porous material disclosed in Japanese Patent Laid-Open No. 6-195004 has excellent characteristics (1) to (5), but the toner adhered to the surface of the guide roller is repeatedly When the agglomerated toner is aggregated in the pores by the cleaning operation performed and the agglomerated toner is recycled into the developing device, it becomes a nucleus to generate toner firefly, and the agglomerated toner is triboelectrically charged with the carrier. It is hard to cause such deterioration, and thus causes various image deterioration such as toner scattering.

The present invention has been made in order to cope with the above situation, and an image forming process in which toner remaining on the photoconductor without being transferred is removed by a cleaning means carrying a guide roller. In addition, in the image forming process employing the toner recycling system in which the toner removed as described above is collected and the collected toner is returned to the developing device or the toner replenishing device and repeatedly reused, No, excellent cleaning properties,
An object of the present invention is to provide an image forming method in which a high-quality image can be stably obtained without damaging the photoreceptor and agglomerating the toner attached to the surface of the guide roller.

[0008]

The above objects of the present invention have been achieved by the following constitutions.

(1) Cleaning means for carrying the toner remaining on the photosensitive member with a toner guide roller having an Asker C hardness of 15 to 50 and having a continuous pore porous body with closed pores on the surface. An image forming method, characterized in that it is removed by using.

The preferred embodiments of the present invention will be described below.

(2) The above-mentioned image forming method, characterized in that a toner recycling system is employed in which the removed toner is returned to a developing device or a toner replenishing device for reuse.

(3) The above-mentioned image forming method, wherein the cleaning means is a cleaning blade.

(4) The above image forming method, wherein the toner guide roller contains a compound having a polyurethane bond.

The present invention will be described in detail below.

In the present invention, since the toner adhered to the surface of the guide roller does not aggregate in the pores even during the repeated cleaning operation, it exhibits sufficient cleaning characteristics, and high image quality is obtained even when the toner after recycling is used. Can be stably formed.

The continuous pore porous body constituting the guide roller of the present invention is mainly composed of a polymer material such as a polyurethane compound, a chloroprene compound, a nitrile-butadiene compound, and a silicon compound. Polyvinyl chloride compounds, polyethylene compounds,
It is also possible to use a polymer material such as a fluororesin compound. However, it is particularly preferable that the continuous pore porous body contains a compound having a polyurethane bond, that is, a polyurethane compound.

The reason for this is that if the constituents of the guide roller are only polymer type polymeric materials that have been conventionally used, the adjustment of the hardness of the guide roller is restricted and, as a result, the pressure contact with the photosensitive member is prevented. At this time, drum scratches are likely to occur, but since sufficient foamability can be obtained by forming the continuous pore porous body by containing the above-mentioned polyurethane-based compound, it is easy to mold and a photosensitive member is obtained. This is because it is possible to adjust to a flexible Asker C hardness that is unlikely to cause a scratch on the drum at the time of pressure contact.

The compound having a polyurethane bond is
It is a general-purpose one and is already known, and can be used without particular limitation.

The continuous porous body which constitutes the guide roller of the present invention is one in which pores having a relatively large particle size are continuously present in the form of a sponge, which is generally a soft foam and has a low viscosity of the raw material and gel. It is produced by using one having a low chemical reaction rate. A foaming agent is used for forming pores, and a polyether / siloxane type is generally used as the foaming agent. In order to obtain continuous pores, the foaming agent uses silicon which is excellent in the property of lowering the surface tension.

In order to produce the above-mentioned porous body having continuous pores, for example, as described in JP-A-58-189242, the above-mentioned polymeric material is dissolved in a good solvent for the material, or the compatibility is improved. A polymer composition solution containing one or more pore-forming agents, which is soluble in the non-solvent of the material, is poured and filled into a mold made by using part or all of the material, and then the polymer is used. The polymer composition is gelled with the material's non-solvent or its vapor, then the gelled product is taken out in or out of the mold, and the pore product is removed by extraction with the polymer's non-solvent or its vapor. By doing so, a product having continuous pores is produced.

Further, as described in, for example, JP-A-60-186886, a fluororesin used for a special purpose is used as a continuous pore body using a polymer material, for example, tetrafluoroethylene resin, 4 fluorine. A fluororesin such as a fluorinated ethylene-6-fluorinated propylene copolymer is formed into a film or tube having various kinds of fine continuous pores by a known method such as a stretching method, a salt elution method, a solvent volatilization method, a sintering method. It is also manufactured by a manufacturing method of molding.

As described above, the guide roller of the present invention is rotated in pressure contact with the photoconductor so as not to damage the photoconductor, and the toner scraped off by the cleaning blade or the like is attached and conveyed to the collection member for smooth collection. In particular, there is a demand for flexible pressure contact of the guide roller with the photoconductor. Further, it is possible to efficiently scrape the toner by using a cleaning blade as the cleaning means, and the scraped toner is returned to the developing device or the toner collecting device by using the guide roller for reuse. Adopting a system enables sufficient cleaning and recycling.

The Asker C hardness according to the present invention is similar to the Asker C hardness described in ordinary technical literature, and the measurement method is also the same.

The Asker C hardness of the guide roller of the present invention is controlled by the pore size of the continuous pore porous body, and the pore size is adjusted by the amount of the foaming agent.

The Asker C hardness of the guide roller of the present invention is from 15 to 50. When the Asker C hardness is less than 15, the guide roller becomes soft and toner spillage occurs. Is not preferable.

According to the present invention, since the guide roller in which the pores on the surface are closed is used, aggregation of the toner occurs in the pores,
A toner that is recycled and developed in the developing device, and aggregated toner becomes nuclei (granular) to cause toner fire (image loss), and frictional electrification between the aggregated toner and the carrier hardly occurs. The problem of scattering does not occur.

As a method for closing the pores existing on the surface of the continuous porous body which constitutes the guide roller of the present invention,
For example, as described in JP-A-58-189242, when a polymer composition solution containing the above-described polymer material and one or more pore-forming agents is injected into a mold, By inserting a film of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) or the like into the mold, and then foaming, a roller in the form of a tube covered on the surface of the continuous pore porous body can be obtained. The tube thickness is 0.
05 to 2 mm is preferable.

A polymer composition solution containing the above-mentioned polymer material and one or more kinds of pore-forming agents as described in JP-A-58-189242, for example, is placed in a mold. Injecting, filling, and then gelling the polymer composition with a non-solvent of the polymer material or its vapor, and then dissolving or having compatibility with the polymer material in a good solvent of the material, and A polymer composition solution containing one or more pore-forming agents that dissolve in the non-solvent of the material is injected into the mold and filled, and then the polymer composition is used in the non-solvent of the polymer material or its vapor. Gelled, and then the gelled product is taken out in or out of the mold, and the pore product is extracted and removed with a non-solvent of the polymeric material or its vapor to increase the pores on the surface of the continuous pore porous body. A roller in a form closed with a molecular material is obtained.

As described above, according to the present invention, the Asker C hardness is 15 to 50 (having flexibility and excellent physical properties and improving durability), and the continuous pore porous body in which the surface pores are closed is used. The above-mentioned problems were solved and outstanding suitability was obtained by an image forming method in which a cleaning means carrying a different guide roller (preventing toner from aggregating in the pores) is used for removal.

The toner used in the present invention may be either a one-component developer or a two-component developer, and is a particle powder containing a colorant and other additives in the binder resin. is there. The number average particle diameter of the toner is usually preferably about 4 to 15 μm. As other additives, for example, a magnetic material, a fixing property improver, a charge control agent, a cleaning property improver, a fluidity improver, etc. can be used.

As a material for the cleaning blade used in the present invention, an elastic body such as silicone rubber or urethane rubber can be used. In this case, the rubber hardness is
30-90 °, thickness 2-10mm, outside the holder is 5
-40 mm, and the pressure contact force with respect to the photoconductor is preferably 5-30 gf / mm.

Next, an example of the cleaning device according to the present invention will be described with reference to FIGS.

In the cleaning device 24 of FIGS. 1 and 2, the guide roller 31 of the present invention having at least the surface of the porous body having continuous pores is incorporated in the cleaning case 25 attached to the frame member 33 of the roller supporting unit 30. , Is in contact with the peripheral surface of the photosensitive drum 20 and is driven in the counterclockwise direction.

That is, the frame member 33 has a pair of side surface portions 33a formed at symmetrical positions thereof, and the frame member 33 has a pair of side holes 33b formed in the respective side surface portions 33a. The roller 31 can be rotated by inserting the fitted bearing 34, and at the same time, the roller 31 is supported so as to be movable in the direction of the peripheral surface of the photosensitive drum 20.

Further, in the bearing 34, a portion of the side surface portion 33a projecting to the outside is a flange portion having a groove having a semicircular cross section on the outer periphery thereof, and the projection 33 on the front side edge of the side surface portion 33a.
A tension spring 35 having both ends fixed to c is wound to urge the guide roller 31 along the elongated hole 33b. The urging of the guide roller 31 by the bearing 34 and the tension spring 35 is symmetrically performed at the left and right ends thereof in good balance.

Further, the frame member 33 has a bent portion 33d formed on its rear side edge so that the scraper 32 can be attached and fixed.
When 33 is attached to the cleaning case 25,
The guide roller 31 at the position pushed back by the peripheral surface of the photoconductor drum 20 is a slenderless plate, a phosphor bronze plate, a tip of the scraper 32 made of an elastic plate such as a Mylar plate with a predetermined load. 31
It is provided at an angle so that it can be pressed into contact with the rotating action of.

Thus, the roller 31 is brought into pressure contact with the photosensitive member 20 and is driven or forcedly rotated, and is provided at the downstream of the cam.
The toner scraped off by the cleaning blade 26, which can be pressed against and separated from the photosensitive drum 20 by 27, is adhered and conveyed by the roller 31, is separated by the scraper 32, and is sent to the collecting member 23. The cleaning blade 26 carried on the holder 40 is rotatably supported by a cam 27 and is pressed against the photosensitive drum 20 by a tension spring 28.

Here, the guide roller 31 is preferably pressed against the photosensitive drum 20 with a linear load of 0.5 to 50 g / cm, and is driven to rotate with a nip width of 0.5 to 4.0 mm when pressed.
The cleaning toner scraped off by the cleaning blade 26 is adhered and conveyed without leakage, and is easily separated by the scraper 32 and collected by the collecting member 23. The guide roller 31 not only allows the cleaning toner to be smoothly collected, but also has the effect of removing paper dust and the like. The angle formed by the cleaning blade 26 carried by the holder 40 and the photoconductor drum 20 is θ ₁ shown in the figure being 2
It is 0 to 90 °, preferably 30 to 75 °.

Next, another example of the cleaning device according to the present invention will be described with reference to FIG. In the figure, 20 is an organic photosensitive drum that rotates in the direction of the arrow, and 24 is the cleaning device,
In the casing 25, a cleaning blade 26 for scraping off the residual toner on the photoconductor and a guide roller for guiding the scraped cleaning toner to the collecting member 62.
31 and 31 are integrated compactly.

The holder 65 of the blade 26 and the toner guide roller 31 are supported by shafts 76 and 71 at both ends of an arm 73 rotatable about 73 as a shaft. It is configured so that the tension of the spring 28 makes it possible to press the surface of the photoreceptor at the same time. Since the guide roller 31 is supported by the shaft 71 via the bearing of the ball bearing, the arm 72 does not restrain the rotation of the guide roller 31.

The guide roller 31 has a casing.
The guide roller 31 is slid and rubbed by a scraper 32 fixed to a scraper supporting portion 77 protruding inward from the lower surface of the guide roller 31.
The upper cleaning toner is collected by the collecting member 62.

Next, the image forming method of the present invention will be described.

In the image forming method of the present invention, a developer comprising at least a toner is used, and the toner remaining on the photosensitive member without being transferred is recovered by a cleaning device,
An image is formed by adopting a toner recycling system in which the collected toner is returned to the developing device or the toner replenishing device for reuse.

FIG. 4 shows an example of an image forming apparatus applicable to the image forming method of the present invention. Reference numeral 14 is a photoconductor, and the photoconductor 14 has a shape of a rotary drum. Photoconductor 14
Around the direction of rotation from upstream to downstream,
A charging device 1, an exposure optical system 2, a developing device 12, a transfer device 5, a separator 6, and a blade type cleaning device 15 are arranged in this order, 10 is a heat roller fixing device, and 9 is a cleaning blade.

In this image forming apparatus, the surface of the photoconductor 14 is charged to a uniform potential by the charger 1 and then imagewise exposed by the exposure optical system 2 so that the surface of the photoconductor 14 is electrostatically charged corresponding to the original. A latent image is formed. This electrostatic latent image is developed by the developer contained in the developing device 12 to form a toner image corresponding to the original. This toner image is transferred onto the transfer material P by the transfer device 5, and is transferred by heating by the heat roller fixing device 10 to form a fixed image. After the transfer material P has passed through the heat roller fixing device 10, the surface of the photoconductor 14 is rubbed by the blade type cleaning device 15 to scrape off the residual toner to obtain the original clean surface, and the charging device is again charged. It is subjected to the charging step of 1 and is used for forming the next image. The toner collected by the cleaning is returned to the developing device 12 again for reuse by a toner recycling system which will be described later in detail.

A specific example of the toner recycling system is shown in FIG.

In the example shown in FIG. 5, 12 is a developing mechanism, 15 is a cleaning mechanism, 19 is a toner receiving and distributing mechanism, 13 is a magnetic brush mechanism, 14 is a photoconductor, 16 is a screw conveyor, and 17 is a first screw. , 18 are second screws, and in the apparatus of this example, the toner from the screw conveyor 16 is supplied to the toner receiving and distributing mechanism 19 by the first screw 17 and the second screw 18. That is, the first screw 17 and the second screw 18,
Each has a rotary shaft and a blade provided spirally along the rotary shaft inside, and in the first screw 17, the toner sent by the screw conveyor 16 is sequentially rotated by the blade as the rotary shaft rotates. The toner is pushed up and sent to the second screw 18, and in the second screw 18, the toner is sequentially sent horizontally in the same principle as the first screw 17 and is supplied to the toner receiving and distributing mechanism 19.
The collected toner is used again for developing the latent image on the photoconductor 14.

[0048]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

Commercially available copying machine (KONICA 6192 Konica Corporation)
An image forming test was carried out using a machine prepared by modifying a product manufactured by the above) into a machine equipped with a negatively charged organic photoreceptor and using a guide roller manufactured as described below.

Samples 1 to 3 of the present invention were prepared by using polyurethane composed of a continuous porous body as shown in Table 1 as the guide roller (Toyo Polymer Ruby Cell).
Further, as comparative examples, four kinds of polyurethanes, each of which is a continuous-pore porous body or an independent-pore foam, are used to prepare samples 4
7 was produced. The PTFE shown in Table 1 is polytetrafluoroethylene, and PVDF is polyvinylidene fluoride. Details of Samples 1 to 7 are shown in Table 1 below.

[0051]

[Table 1]

Next, the contact load of the cleaning blade
Contact load of guide roller at 15.5 g / f / cm 40.0 g / f
/ Cm, 20 ° C, RH, 60% atmosphere, 10,000 copies each were made, and the characteristics of four items were measured and evaluated. In this example, a toner having a number average particle size of 8 μm was used.
As the cleaning conditions, the examination was conducted under the conditions of the above copying machine except for the guide roller.

The results are shown in Table 2 below.

[0054]

[Table 2]

(Evaluation method and conditions) -Toner firefly-Toner firefly was evaluated by running three copies of a completely black original document (image density 1.3) after running 10,000 copies and determining the number of toner firefly on the image. It was measured.

-Fog-The fog evaluation method was as follows: After running 10,000 copies, an entire white original was copied, and a Macbeth densitometer (RD 918 Macbeth) was used.
The density of fog was measured using. Fog density is 0.00
3 or less was marked with ⊚ and 0.01 or more was marked with x.

-Drum scratches-Drum scratches were evaluated by observing scratches on the drum surface after 10,000 copy running with a laser microscope (ILM21 Lasertec Co., Ltd.).
The number was 50 or less, and the number of 500 or more was x.

-Spillage- The spillage was evaluated by collecting the toner in the lower part of the cleaning unit after running 10,000 copies and judging the amount of collected toner. The collected toner amount was rated as ⊚ when the amount was 0.05 g or less, and as x when the amount was 0.1 g or more.

As is clear from Table 2, Samples 1 to 1 of the present invention
In No. 3, the occurrence of toner firefly was very small, there was little fog, and the drum scratches and spills were excellent.
Has a large amount of toner fireflies, and fog has also occurred.
Furthermore, it was revealed that Samples 5 to 7 were inferior to any of fog, drum scratches, and spills, and were not practical.

[0060]

According to the image forming method using the guide roller of the present invention, when the image is formed by repeating a large number of times, the surface of the photoconductor is not damaged by the guide roller and is scraped off by the cleaning blade. Remaining toner on the photoconductor is always smoothly collected by the collecting member, and further, a high-quality image free from defects such as toner firefly and fog can be stably obtained, and remarkably excellent effects are exhibited.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a cleaning device having a guide roller of the present invention.

FIG. 2 is a cross-sectional view showing another example of the cleaning device of the present invention.

FIG. 3 is a sectional view showing still another example of the cleaning device of the present invention.

FIG. 4 is a sectional view showing an example of an image forming apparatus applicable to the image forming method of the present invention.

FIG. 5 is a plan view of the toner recycling system of the present invention.

[Explanation of symbols]

 20 Photoconductor drum 26 Cleaning blade 27 Cam 31 Guide roller 32 Scraper

Claims (4)

[Claims] 1. A cleaning means for carrying the toner remaining on the photosensitive member, carrying a toner guide roller having an Asker C hardness of 15 to 50 and having on the surface a continuous pore porous body with closed surface pores. An image forming method characterized by using and removing. 2. The image forming method according to claim 1, wherein a toner recycling system is used in which the removed toner is returned to a developing device or a toner replenishing device for reuse. 3. The image forming method according to claim 1, wherein the cleaning unit is a cleaning blade. 4. The toner guide roller contains a compound having a polyurethane bond.
4. The image forming method according to any one of 3 to 3.