JPH08179667A - Image forming method using toner guiding roller - Google Patents

Abstract

PURPOSE: To provide an image forming method by which images having high quality are stably obtd. with excellent cleaning characteristics without damaging a photoreceptor and without flocculating toners in the pares of a toner guiding roller in the process of image formation to repetitively reutilize the toners by recovering the residual toners by the toner guiding roller and returning these recovered toners to a developing device or toner replenishing device. CONSTITUTION: A toner recycling system to recover the toners remaining on the photoreceptor 20 by a cleaning means 26 and to return the recovered toners to the developing device or toner replenishing device so as to reutilize the toners is adopted in this image forming method, in which the toner guiding roller having pares of the number average pore size R expressed by the equation (1/4)×D<=R<=D on its surface is used. D: the number average grain size of the toners, R: the number average pore size (length in the major axis direction) of the pores.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method using a guide roller for collecting toner for electrophotography.

[0002]

2. Description of the Related Art Conventionally, in the electrophotographic method based on the Carlson method, the surface of an image forming body is uniformly charged, imagewise exposed 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]

According to the research conducted by the present inventors for many years, the toner guide roller is required to satisfy the following specific conditions in order to fully exhibit its function. .

That is, (1) the durability of the guide roller itself is high, the mechanical wear resistance is strong, and the action of discharge active species such as ozone is strong because it is relatively close to corona discharge. (2) Image The toner scraped off from the formed body can be smoothly conveyed by adhering to the guide roller surface, and it has excellent transportability, and in order to smoothly collect the adhered toner with the scraper, the adhered toner from the guide roller is removed. Good separability (3) The guide roller does not wear and damage the surface of the image forming body when it rotates. (4) The surface of the guide roller has appropriate flexibility, and the toner is spilled by closely contacting the surface of the image forming body and rotating. (5) It has an efficiency of removing the paper dust that adheres in the transfer step. (6) The toner adhered to the surface of the guide roller is collected without being aggregated.

In particular, in an image forming method employing a toner recycling system in which toner that has not been transferred and remains on the photosensitive member is recovered by a cleaning means, and the recovered toner is returned to a developing device or a toner replenishing device for reuse.
If the aggregated toner adhering to the surface of the guide roller is recovered without the condition (6) being set, problems such as toner fireflies and image fogging occur.

Conventionally, cleaning means such as a fur brush for cleaning, a cleaning blade or a cleaning roller has been proposed. In particular, the cleaning roller disclosed in JP-A-6-195004 has the above characteristics (1) to (5). Are better.

However, in the above cleaning roller, when the toner adhered to the surface of the guide roller is aggregated in the pores by the repeated cleaning operation, and the aggregated toner is recycled into the developing device, In some cases, toner firefly is generated by using as a core, and the agglomerated toner is less likely to be triboelectrically charged with the carrier, which causes various kinds of image deterioration such as toner scattering.

The present invention has been made in order to cope with the above situation, and collects the toner remaining on the photosensitive member without being transferred by the toner guide roller, and the collected toner is collected by the developing device or the toner. In the process of image formation in which the toner is returned to the replenishing device and repeatedly reused, it does not have the above-mentioned drawbacks, has excellent cleaning characteristics, does not damage the photoconductor, and does not aggregate toner in the pores of the toner guide roller. An object of the present invention is to provide an image forming method capable of stably obtaining a high quality image.

[0010]

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

(1) In the image forming method employing a toner recycling system in which the toner remaining on the photoconductor is collected by a cleaning means, and the collected toner is returned to a developing device or a toner replenishing device for reuse. An image forming method characterized by using a toner guide roller having pores with a number average pore diameter R represented by (1) on the surface.

General formula (1) (1/4) × D ≦ R ≦ D [D: number average particle diameter of toner, R: number average pore diameter of pores (length in major axis direction)] A preferred embodiment will be described.

(2) The above image forming method, wherein the toner cleaning means is a cleaning blade.

(3) The image forming method described above, 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, the toner remaining on the photoconductor is collected by a cleaning means using a toner guide roller having pores of the number average pore diameter R represented by the general formula (1) on the surface, and the collected toner. This is an image forming method that employs a toner recycling system in which toner is returned to a developing device or a toner replenishing device and reused. With the above configuration, the toner adhered to the surface of the guide roller is repeatedly cleaned without damaging the photoreceptor. It is possible to stably form a high image quality without agglomeration in the pores even by the operation.

The number average pore diameter R in the present invention is obtained by cutting the surface of the toner guide roller and observing the surface with an SEM (T330, manufactured by JEOL), SIA (SCANNING IMAGE ANALYZER) (LA-52
5, manufactured by JEOL).

In the present invention, if the pore diameter of the pores on the surface of the toner guide roller is not less than the number average particle diameter (D) of the toner, the toner enters the pores and the toner aggregates in the pores.

When the agglomerated toner is recycled into the developing device and developed, the agglomerated toner serves as nuclei to generate toner fireflies, and the triboelectric charging between the agglomerated toner and the carrier hardly occurs. Scattering occurs.

If the diameter of the pores on the surface of the toner guide roller becomes 1/4 or less of the number average particle diameter (D) of the toner, the roller becomes rigid and damages the photoconductor, resulting in image deterioration. Connect

As described above, the toner 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 by the cleaning blade is adhered and conveyed and smoothly collected by the collecting member. In particular, there is a demand for flexible pressure contact of the toner guide roller with the photoconductor.

As described above, in the toner guide roller, it is necessary to enlarge the air bubbles of the roller in order to flexibly press it against the photosensitive member. However, if the air bubbles of the roller are increased, the physical properties of the roller become weak and the durability deteriorates. To do.

Therefore, the present invention has pores having the number average pore diameter R represented by the above general formula (1) (prevents toner from aggregating in the pores), and has flexibility and excellent physical properties. An image forming method using a toner guide roller having improved durability has solved the above-mentioned problems and obtained outstanding suitability.

The toner guide roller of the present invention is mainly composed of polyurethane compound, chloroprene compound, nitrile.
The mainstream is a polymer material such as a butadiene-based compound or a silicon-based compound, but a polymer material such as a polyvinyl chloride-based compound, a polyethylene-based compound or a fluororesin-based compound may be used. However, it is particularly preferable that the toner guide roller of the present invention contains a compound having a polyurethane bond, that is, a polyurethane compound.

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 toner guide roller of the present invention is preferably either a continuous pore porous type or an independent pore firing type.

The continuous pore porous type is one in which pores having a relatively large particle size are continuously present in the form of a sponge,
Generally, a flexible foam having a low viscosity of a raw material and a low gelation reaction rate is used. A foaming agent is used for forming pores, and a polyether / siloxane type is generally used as the foaming agent. To obtain open pores, the foaming agent relies on silicon, which has excellent surface tension lowering properties.

In addition, the open-cell foam type has pores with a relatively small particle size separated from each other in contrast to the continuous-pore porous type, and is generally a rigid foam, which has a high viscosity of the raw material and a degree of crosslinking. It is made using a high one. In order to obtain independent pores, the polyether chain as a foaming agent generally uses ethylene oxide.

To manufacture the toner guide roller,
For example, as described in JP-A-58-189242, one or two of the above-mentioned polymeric materials, which are soluble or compatible with a good solvent of the material, and which are soluble in a non-solvent of the material. A polymer composition solution containing the above pore-forming agent is poured into and filled in a mold which is partially or wholly used, and then the polymer composition is gelled with a non-solvent of the polymer material or its vapor. Then, the gelled product is taken out in the mold or out of the mold, and the pore product is extracted and removed with a non-solvent of the polymer material or its vapor to produce a product having open pores or closed cells. .

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 resin. Fluorine resin such as chlorinated ethylene-6-fluorinated propylene copolymer is drawn into a film or tube having various fine continuous pores by a known method such as a stretching method, a salt elution method, a solvent volatilization method, and a sintering method. It is also manufactured by a manufacturing method of molding.

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

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

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

That is, the frame member 33 has a pair of side surface portions 33a formed at symmetrical positions, and the frame member 33 has a pair of side holes 33b formed in the respective side surface portions 33a, and is attached to the support shaft 31a at the left and right ends of the guide roller 31. By inserting the fitted bearing 34, the roller
31 is rotatably supported and is movably supported 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 guide roller using the bearing 34 and the tension spring 35.
It is assumed that the urging of 31 is balanced and symmetrical at the left and right ends.

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 peripheral surface of the guide roller 31 at the position pushed back by the peripheral surface of the photoconductor drum 20 covers the peripheral surface of the guide roller 31 made of an elastic plate such as a SUS plate, a phosphor bronze plate, or a Mylar plate with the tip of the scraper 32 having a predetermined load. It is set at an angle so that it can be pressed against the rotation of 31.

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

The toner 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 at the time of pressing, and the cleaning blade is used. The cleaning toner scraped off at 26 is adhered and conveyed without leakage, and is easily separated by the scraper 32 and collected by the collecting member 23. The toner 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.

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 cleaning case 25, a cleaning blade 26 for scraping off the residual toner on the photosensitive member and a toner guide roller 31 for guiding the scraped cleaning toner to the collecting member 62 are integrally and compactly incorporated. .

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 72 rotatable about a shaft 73, and a tension spring connected to the shaft 76. It is configured so that it can be pressed against the surface of the photoreceptor at the same time by the tension of 28. Since the toner 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 toner guide roller 31.

Further, the toner guide roller 31 has a scraper supporting portion projecting to the inner surface below the cleaning case 25.
The cleaning toner on the toner guide roller 31 is rubbed by the scraper 32 fixed to the collecting member 62.
Be recovered.

Here, the toner guide roller 31 of FIG. 3 uses the continuous pore porous body having the structure of FIG. 1 and has an excellent cleaning toner recovery characteristic.

Next, the image forming method of the present invention will be described. The two-component developer will be described below, but a one-component developer may be used in the present invention.

In the image forming method of the present invention, a two-component developer comprising a carrier and a toner is used, the toner remaining on the photosensitive member without being transferred is collected by a cleaning device, and the collected toner is collected by the developing device or the toner. An image is formed by using a toner recycling system in which the toner is returned to the replenishing device and reused.

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 form 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 inside of the developing device 12 again for reuse by a toner recycling system 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.

[0049]

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

KONICA 619 equipped with a positively chargeable inorganic photoconductor
2 and a machine modified from this for a negatively charged organic photoconductor were used, and an image forming test was conducted using a toner guide roller manufactured as described below.

As the toner guide roller (Toyo Polymer Co., Ltd., Rupeetel), samples 1 to 3 of the present invention were prepared by using a polyurethane having a continuous pore porous body or an independent pore foaming body as shown in Table 1, and Comparative Examples. Samples 4 and 5 were prepared by using the same two types of polyurethane. The contact load of the cleaning blade is 15.5 g / f / cm, the contact load of the toner guide roller is 40.0 g / f / cm, and 10,000 copies are made under the atmosphere of 20 ° C, RH and 60%. It was measured and evaluated. In this example, the number average particle diameter D
8 μm toner was used. The results are shown in Table 1 below.

[0052]

[Table 1]

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

-Fog-A 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.).
Observing using a number of 50 or less with a width of 1 μm or more ◎, 5
00 and above were marked with x.

As is clear from Table 1, Samples 1 to 1 of the present invention
In No. 3, no toner firefly was generated, which was excellent. However, in Comparative Example 4, drum scratches were produced, and in Comparative Example 5, a large amount of toner firefly was produced and fog was also generated, which revealed that it was not practical. It was

[0057]

According to the image forming method using the toner guide roller of the present invention, there is no damage on the surface of the photosensitive member by the guide roller when the image is formed a number of times, and the image is scraped off by the blade. The residual 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, which is remarkably excellent.

[Brief description of drawings]

FIG. 1 is a cross-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 cross-sectional view showing an example of an image forming apparatus using the cleaning device 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 Toner guide roller 32 Scraper

Claims (3)

[Claims] 1. An image forming method employing a toner recycling system in which toner remaining on a photoconductor is collected by a cleaning means, and the collected toner is returned to a developing device or a toner replenishing device for reuse. 1)
An image forming method characterized by using a toner guide roller having pores having a number average pore diameter R represented by General formula (1) (1/4) × D ≦ R ≦ D [D: number average particle diameter of toner, R: number average pore diameter of pores (length in major axis direction)] 2. The image forming method according to claim 1, wherein the toner cleaning means is a cleaning blade. 3. The image forming method according to claim 1, wherein the toner guide roller contains a compound having a polyurethane bond.