JP7139761B2 - cleaning equipment - Google Patents

Description

The present invention relates to cleaning devices.

Conventionally, in image formation by electrophotography, a latent image is formed by electrostatic charges on an image carrier such as a photoconductive material, and charged toner particles are adhered to the electrostatic latent image to form a visible image. forming. The visible image formed by the toner is finally transferred to a transfer medium such as paper, and then fixed on the transfer medium by heat, pressure, solvent gas, or the like to form an output image. These image forming methods include the so-called two-component developing method, which uses triboelectrification by stirring and mixing toner particles and carrier particles, and the method that does not use carrier particles. It is roughly classified into a so-called one-component development system in which charge is applied to toner particles immediately. The one-component developing method is classified into a magnetic one-component developing method and a non-magnetic one-component developing method depending on whether or not a magnetic force is used to hold the toner particles on the developing roller.

Until now, copiers and multifunction devices based on them, which require high speed and image reproducibility, have been using two-component Development methods are often used, and single-component development methods have been widely used in compact printers, facsimiles, and the like, which are highly demanded for space-saving, low-cost, and the like. In addition, especially in recent years, the colorization of output images has progressed, and the demand for higher image quality and stabilization of image quality is stronger than ever. In order to improve image quality, the average particle size of the toner is becoming smaller, and the shape of the particles is becoming more round without angular portions. In these electrophotographic image forming apparatuses, a drum-shaped or belt-shaped image bearing member (generally a photoreceptor) is rotated and uniformly charged, regardless of the difference in developing method. A latent image pattern is formed on the image carrier by the image carrier, visualized by the developing device, and transferred onto the transfer medium.

2. Description of the Related Art In an image forming apparatus that forms an image by electrostatically transferring a toner image formed on the surface of an image carrier onto a transfer medium, it is necessary to clean residual toner on the image carrier after the transfer process. Therefore, a cleaning blade made of urethane rubber or the like, which is pressed against the surface of the image carrier, is generally used. However, depending on the operating conditions and environment of the image forming apparatus, it may be difficult to completely remove all residual toner, resulting in defective cleaning. In particular, when the behavior of the cleaning blade becomes unstable and a vibration phenomenon called stick-slip occurs, the frequency of toner slipping through the cleaning blade tends to increase. In order to clean the toner without causing this cleaning failure, there is a technique in which silica externally added to the toner is deposited on the edge of the cleaning blade, and the blocking force of the silica improves the cleanability of the toner ( See Patent Document 1).

However, although the technology disclosed in Japanese Patent Application Laid-Open No. 2002-200000 has a certain improvement effect in toner cleaning, there is a problem that the behavior of the cleaning blade becomes unstable (the amplitude is large) and cleaning failure occurs. .

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a space-saving and low-cost cleaning device that stabilizes the behavior of a cleaning blade and has excellent cleaning performance.

The above problem is solved by the following configuration 1).
1) An object to be cleaned which is a rotating body, first particles adhering to the object to be cleaned, second particles smaller in diameter than the first particles, and second particles adhering to the object to be cleaned. In a cleaning device having a cleaning blade, which is a cleaning member for cleaning one particle, and a blade nip, which is a contact surface between the cleaning blade and the object to be cleaned, at least a part of the blade nip includes the first Two particle layers are formed, the average layer thickness of the second particle layer is 0.1 μm or more and 2 μm or less, the average layer thickness is an average of positions, and the area of the blade nip is the A cleaning device, wherein the coverage (C) of the layer of the second particles is 35% or more .

According to the present invention, it is possible to provide a space-saving and low-cost cleaning device that stabilizes the behavior of the cleaning blade and has good cleaning performance.

FIG. 5 is a diagram for explaining states of toner, silica particles, and a blade nip in the prior art and the present invention; FIG. 5 is a diagram for explaining states of toner, silica particles, and a blade nip in another prior art; FIG. 3 is a diagram for explaining the relationship between cleanability, the BET specific surface area of silica particles, and the average layer thickness of a layer of silica particles. 1 is a schematic configuration diagram of a cleaning blade for explaining an embodiment of a cleaning device according to the present invention; FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus; FIG. 2 is a schematic configuration diagram showing an example of an image forming unit included in the image forming apparatus; FIG. FIG. 4 is an explanatory diagram for explaining a method of measuring the circularity of toner; Fig. 3 is a graph showing the relationship between coverage (C) and 100% modulus (M100) of the blade edge layer; 4 is a graph showing the relationship between coverage (C) and hardness (H) of the blade edge layer. FIG. 2 is a schematic diagram of the results of microscopic observation of silica particle layers in Examples 1 to 3. FIG.

Hereinafter, embodiments of the present invention will be further described with reference to the drawings, but the present invention is not limited to the following embodiments.

As described above, Patent Document 1 relates to a technique in which silica externally added to toner is deposited on the edge portion of a cleaning blade to improve toner cleanability by blocking force of silica. There was a problem that it became unstable and cleaning failure occurred. As a result of repeated studies on the reason for this, the inventors of the present invention have found that the tip of the blade nip, which is the contact surface of the cleaning blade and the object to be cleaned, is greatly involved during cleaning, increasing the frictional force and cleaning the toner and silica at the same time. It was found that the cause was that the amount of silica deposited decreased due to slipping through the blade. Furthermore, as a result of repeated studies by the present inventors, in order to solve the above problem, particles are present in a specific layer thickness in at least a part of the blade nip to reduce the frictional force, and the cleaning blade We found that it is effective to stabilize the behavior of

Therefore, the cleaning device of the present invention comprises a rotating object to be cleaned, first particles adhering to the object to be cleaned, second particles smaller in diameter than the first particles, and the object to be cleaned. a cleaning blade that is a cleaning member for cleaning first particles adhering to an object; and a blade nip that is a contact surface between the cleaning blade and the object to be cleaned, and at least part of the blade nip Second, the layer of the second particles is formed, and the average layer thickness of the layer of the second particles is 0.1 μm or more and 2 μm or less.

The average layer thickness of the layer of the second particles is preferably 0.1 μm or more and 1 μm or less, more preferably 0.5 μm or more and 1 μm or less.

In the following, an example will be described in which a photosensitive member is used as the object to be cleaned, toner is used as the first particles, and silica particles are used as the second particles.
FIG. 1 is a diagram for explaining states of toner, silica particles, and a blade nip in the prior art and the present invention.
In the initial state of FIG. 1(a), in the prior art, silica particles are deposited in front of the blade nip (on the upstream side in the rotation direction of the photoreceptor), but there is no layer of silica particles in the blade nip, or Since it is present in very little, if any, the coefficient of friction between the cleaning blade and the photosensitive layer is relatively high. When the photoreceptor is rotated in this state, the frictional force that the cleaning blade receives from the photoreceptor is relatively large, so the stick-slip amplitude of the cleaning blade tends to increase. As a result, (b) the cleaning blade climbs over silica deposited before the blade nip over time, and a large amount of toner slips through along with the silica particles, resulting in a significant reduction in deposited silica particles. In (c) Elapsed Time 2, the deposition of silica particles completely disappears, and the toner adhering to the cleaning blade lifts the blade, causing continuous cleaning failures.
On the other hand, in the present invention, (a) in the initial state, a silica particle layer is formed in at least a part of the blade nip, and the average layer thickness of this silica particle layer is 0.1 μm or more and 2 μm or less, The coefficient of friction is stable and low. Therefore, the frictional force that the cleaning blade receives from the photoreceptor is small, and as a result, the amplitude of stick-slip can be reduced. As a result, (b) the cleaning blade is prevented from getting over the silica deposited in front of the blade nip over time, and (c) the layer of silica particles is stably maintained even after time 2 has passed, and can be used for a long period of time. Cleanability is improved.

In the present invention, as described above, "a second layer of particles (a layer of silica particles in this embodiment) is formed in at least a part of the blade nip, and the average layer thickness of the layer of silica particles is 0.5. 1 μm or more and 2 μm or less”. Means for achieving such conditions are described below.

FIG. 2 is a diagram for explaining states of toner, silica particles, and a blade nip in another prior art.
According to studies by the present inventors, silica particles existing before the blade nip often form a higher-order structure such as aggregates or agglomerates. As shown in FIG. 2(a), when silica particles have high agglomeration and low fluidity, silica particle aggregates are formed in front of the blade nip, and no layer of silica particles is formed in the blade nip. Only the same effects as those of the technology disclosed in Patent Document 1 can be obtained. In addition, silica particle aggregates may intermittently slip through the blade nip. On the other hand, when the silica particles have low agglomeration and too high fluidity, as shown in FIG. . Thus, in order to achieve the above conditions in the present invention, it is necessary to appropriately set the aggregation properties of silica particles.

A major characteristic value that contributes to the cohesiveness of silica particles is the BET specific surface area.
In the present invention, in order to form a layer of silica particles in at least a part of the blade nip and have an average layer thickness of 0.1 μm or more and 2 μm or less, for example, the BET specific surface area of the silica particles is , preferably 10 to 400 m ² /g, particularly preferably 35 to 110 m ² /g.
The BET specific surface area is measured according to JIS Z8830.

FIG. 3 is a diagram for explaining the relationship between cleanability, the BET specific surface area of silica particles, and the average layer thickness of a layer of silica particles.
In FIG. 3, the relationship between the BET specific surface area of the silica particles and the average layer thickness of the silica particle layer can take the relationship of curve A, for example. In the present invention, the average layer thickness of the silica particle layer must be T1 (0.1 μm) or more and T2 (2 μm) or less. can be said to be the range in which the effect of

If the average layer thickness of the silica particle layer is less than T1, a sufficient effect of lowering the coefficient of friction cannot be obtained, and the behavior of the blade becomes unstable, resulting in defective cleaning. On the other hand, when the average layer thickness of the silica particle layer exceeds T2, the silica particles that have entered the blade nip agglomerate, and the agglomerated silica particles take in non-aggregated silica particles while moving downstream of the blade nip. slip through. As a result, the amount of silica particles in the blade nip temporarily decreases, and the behavior of the blade becomes unstable, which may result in defective cleaning. On the other hand, when the BET specific surface area of the silica particles is less than A1, the adhesion between the cleaning blade and the silica particles is reduced, and most of the silica particles slip through the downstream side of the blade nip. Conversely, the BET specific surface area of the silica particles exceeds A2. Then, the silica particles are excessively agglomerated and do not advance into the blade nip, and the blade behavior becomes unstable, resulting in poor cleaning.

According to studies by the present inventors, the layer of the second particles (for example, silica) tends to be formed in the direction from the downstream side to the upstream side in the rotation direction of the object to be cleaned. Alternatively, the layer of second particles may not evenly cover the entire blade nip. In this form, the coverage (C) of the second particle layer with respect to the area of the blade nip is preferably 35% or more, more preferably 50% or more. By satisfying this condition, the frictional force that the cleaning blade receives from the photoreceptor is reduced, the behavior of the blade is stabilized, and the cleaning performance is improved.

Furthermore, according to the studies of the present inventors, between the coverage (C) and the 100% modulus (M100) of the blade edge layer forming the blade nip, as well as the coverage (C) and the blade edge It was found that there is a certain correlation between the hardness (H) of the layer and the cleanability.
FIG. 8 is a graph showing the relationship between the coverage (C) and the 100% modulus (M100) of the blade edge layer. FIG. 9 is a graph showing the relationship between the coverage (C) and the hardness (H) of the blade edge layer.
○ on the graph indicates good cleaning performance, and Δ indicates practically sufficient cleaning performance.
To obtain good cleanability, the higher the 100% modulus (M100) or hardness (H), the lower the coverage (C) can be. The reason for this is that the higher the 100% modulus (M100) or hardness (H), the narrower the blade nip area (nip width). When the nip width is narrow, the particles tend to be concentrated on the downstream side of the blade nip, and the second particles enter this portion to obtain the effect of lowering the coefficient of friction most efficiently. That is, the higher the 100% modulus (M100) or hardness (H), the lower the coverage (C). On the other hand, when the 100% modulus (M100) or hardness (H) shows a low value and the nip width is wide, the blade on the downstream side of the blade nip is greatly involved and the contact area becomes large, resulting in a high coverage ( C) is required.

From the above knowledge, in the present invention, it is preferable that the coverage (C) and the 100% modulus (M100) of the blade edge layer satisfy the following relationship.
C≦−4.7×(M100)+60
C≧−1.1×(M100)+22
However, 2≤(M100)≤10.5
By determining the coverage (C) so as to satisfy the above relationship according to the 100% modulus (M100) of the blade edge layer, the frictional force that the cleaning blade receives from the photoreceptor is reduced, the blade behavior is stabilized, and cleaning is performed. improve sexuality.
The 100% modulus (M100) is measured according to JIS K 6251 and its unit is MPa.
The 100% modulus (M100) of the blade edge layer is preferably 5-10.5 MPa, more preferably 7-10.5 MPa.

Further, from the above findings, in the present invention, it is preferable that the coverage (C) and the hardness (H) of the blade edge layer satisfy the following relationship.
C≦−1.5×(H)+148
C≧−0.3×(H)+44
However, 64≤(H)≤90
By determining the coverage (C) so as to satisfy the above relationship according to the hardness (H) of the blade edge layer, the frictional force that the cleaning blade receives from the photoreceptor is reduced, the behavior of the blade is stabilized, and the cleaning performance is improved. improves.
The hardness (H) is measured according to JISK 6253 (JIS A rubber hardness).
The hardness (H) of the blade edge layer is preferably 70-90, more preferably 80-90.

In the present invention, the 100% modulus (M100) of the blade edge layer, the bulk density (ρ) of the second particles and the average particle size (D) of the second particles preferably satisfy the following relationship.
0.0016≦(M100)×{(ρ)/(D)}≦0.27
By satisfying this relationship, the formation of the second particles in the blade nip is facilitated, and the average layer thickness of the layer of the second particles can be well adjusted within the range defined by the present invention.
The bulk density (ρ) is measured according to JIS K5101.
The average particle size (D) can be measured by electron microscopic observation.
Also, the bulk density (ρ) of the second particles is preferably 0.2 to 0.5 g/cm ³ .

The primary average particle size of the second particles is preferably set to 15 nm to 160 nm, more preferably 50 nm to 160 nm, and particularly preferably 100 nm to 130 nm.
When the primary average particle size of the second particles is 15 nm or more, the number of particles slipping through the blade nip is reduced, and the layer of the second particles can be formed satisfactorily. Even when the second particles pass through the blade nip, the desired effect can be obtained if the second particles can be continuously and sufficiently supplied into the blade nip. Further, when the average particle size of the second particles is 160 nm or less, the particles can easily enter the blade nip, and a sufficient effect of reducing the frictional force can be obtained.

Next, one embodiment of the cleaning device according to the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a cleaning blade. The cleaning blade 15 is a two-layered blade member composed of a blade edge layer 15a-1 including an edge portion that contacts the photosensitive drum 3 and a backup layer 15a-2. This blade member can be produced by successively stacking layers by known centrifugal molding. The blade member is adhesively fixed to an L-shaped metal blade holder 15a-3. The blade edge layer 15a-1 and the backup layer 15a-2 are made of different materials and have different hardnesses.
A blade nip 15c is formed at the contact surface between the blade edge layer 15a-1 and the photoreceptor 3. As shown in FIG.

<Cleaning object>
The object to be cleaned is not particularly limited in terms of its material, shape, structure, size, etc., other than the photoreceptor, and can be appropriately selected according to the purpose. Examples of the shape of the object to be cleaned include a drum shape, a belt shape, a flat plate shape, and a sheet shape. The size of the object to be cleaned is not particularly limited and can be appropriately selected depending on the purpose, but a size that is normally used is preferable.

The material of the object to be cleaned is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include metals, plastics, and ceramics.

<First particles>
The first particles adhering to the cleaning object are not particularly limited as long as they adhere to the cleaning object and can be removed by the cleaning blade, and can be appropriately selected according to the purpose. , for example, toners, lubricants, inorganic fine particles, organic fine particles, dirt, dust, or mixtures thereof. Among these, toner is preferred.

<Backup layer>
The shape, material, size, structure, etc. of the backup layer 15a-2 are not particularly limited, and can be appropriately selected according to the purpose.
Examples of the shape include plate-like, strip-like, sheet-like, and the like.
The size is not particularly limited, and can be appropriately selected according to the size of the member to be cleaned.
The material is not particularly limited and can be appropriately selected depending on the intended purpose. Polyurethane rubber, polyurethane elastomer, and the like are preferable because high elasticity can be easily obtained.

<Blade edge layer>
The blade edge layer 15a-1 is not particularly limited and can be appropriately selected depending on the purpose.
The material of the blade edge layer 15a-1 is not particularly limited and can be appropriately selected according to the purpose. and the like.

<Second particle>
In the above embodiments, silica particles are mainly used as the second particles, but the present invention is not limited to this, and other particles can also be used as the second particles.
Examples thereof include boron nitride (BN) and fluorine particles, and the particle conditions such as BET specific surface area and average particle diameter are the same as those of the silica particles.

As a method of supplying the second particles, a layer of the second particles is formed in at least a part of the blade nip, and the average layer thickness of the layer of the second particles is 0.1 μm or more and 2 μm or less. is not particularly limited, and for example, a method of supplying a necessary amount of the second particles as needed can be mentioned. A preferred method is to use silica particles as an external additive, and to liberate a portion of the silica particles to continuously enter the blade nip of the cleaning blade. In this embodiment, the amount of silica particles added is, for example, about 1 to 5% by mass, more preferably 3 to 4.5% by mass, based on the total toner.

The cleaning blade 15 of this embodiment can be widely used in various fields, and is particularly suitable for use in the process cartridge and image forming apparatus described below.

(Process cartridge, image forming apparatus and image forming method)
The process cartridge has at least an image carrier and cleaning means for removing toner remaining on the image carrier, and the cleaning means has the cleaning blade 15 of the present invention. A mechanism for applying a lubricant to the surface of the latent image carrier may be provided as a cleaning aid.

The image forming apparatus includes an image carrier, charging means for charging the surface of the image carrier, exposure means for exposing the charged image carrier to form an electrostatic latent image, and the electrostatic latent image. is developed using toner to form a visible image; transfer means for transferring the visible image onto a recording medium; fixing means for fixing the transferred image transferred onto the recording medium; and cleaning means for removing toner remaining on the carrier, and the cleaning blade 15 of the present invention is used as the cleaning means. The image carrier may be provided with a mechanism for applying a lubricant as a cleaning aid.

An electrophotographic printer (hereinafter simply referred to as printer 500) as an image forming apparatus to which the present invention is applied will be described below. First, the basic configuration of the printer 500 according to this embodiment will be described.

FIG. 5 is a schematic configuration diagram showing the printer 500. As shown in FIG. The printer 500 has four image forming units 1Y, C, M and K for yellow, magenta, cyan and black (hereinafter referred to as Y, C, M and K). They use Y, C, M, and K toners of different colors as image forming substances for forming images, but otherwise have the same configuration.

A transfer unit 60 having an intermediate transfer belt 14 as an intermediate transfer member is arranged above the four image forming units 1 . Toner images of respective colors formed on the surfaces of the photoreceptors 3Y, C, M, and K provided in the respective image forming units 1Y, C, M, and K, which will be detailed later, are superimposed on the surface of the intermediate transfer belt . It is a configuration to be transcribed.

An optical writing unit 40 is arranged below the four image forming units 1 . The optical writing unit 40, which is a latent image forming means, irradiates the photoreceptors 3Y, C, M, K of the image forming units 1Y, C, M, K with laser light L emitted based on image information. As a result, electrostatic latent images for Y, C, M, and K are formed on the photoreceptors 3Y, C, M, and K, respectively. The optical writing unit 40 deflects the laser light L emitted from the light source by a polygon mirror 41 rotated by a motor, and writes the light onto the photoreceptors 3Y, C, M, and K via a plurality of optical lenses and mirrors. It irradiates to Instead of such a configuration, it is also possible to employ a device that performs optical scanning using an LED array.

Below the optical writing unit 40, a first paper cassette 151 and a second paper cassette 152 are arranged so as to overlap vertically. In each of these paper feed cassettes, a plurality of sheets of transfer paper P, which are recording media, are accommodated in a paper bundle state. The second paper feed rollers 152a are in contact with each other. When the first paper feed roller 151a is driven to rotate counterclockwise in the figure by the drive means, the uppermost transfer paper P in the first paper feed cassette 151 extends vertically in the right side of the cassette in the figure. The sheets are discharged toward the paper feed path 153 arranged so as to be present. Further, when the second paper feed roller 152a is driven to rotate counterclockwise in FIG. be done.

A plurality of transport roller pairs 154 are arranged in the paper feed path 153 . The transfer paper P fed into the paper feed path 153 is conveyed from the lower side to the upper side in FIG.

A registration roller pair 55 is arranged at the downstream end of the paper feed path 153 in the transport direction. As soon as the registration roller pair 55 sandwiches the transfer paper P sent from the conveying roller pair 154 between the rollers, the rotation of both rollers is temporarily stopped. Then, the transfer paper P is fed toward a secondary transfer nip, which will be described later, at an appropriate timing.

FIG. 6 is a configuration diagram showing a schematic configuration of one of the four image forming units 1. As shown in FIG.
As shown in FIG. 6, the image forming unit 1 includes a drum-shaped photosensitive member 3 as an image carrier. Although the photoreceptor 3 has a drum-like shape, it may have a sheet-like shape or an endless belt-like shape.
Around the photoreceptor 3, a charging roller 4, a developing device 5, a primary transfer roller 7, a cleaning device 6, a lubricant coating device 10, a static elimination lamp, and the like are arranged. The charging roller 4 is a charging member included in a charging device as charging means, and the developing device 5 is a developing means for converting the latent image formed on the surface of the photoreceptor 3 into a toner image. The primary transfer roller 7 is a primary transfer member provided in a primary transfer device as primary transfer means for transferring the toner image on the surface of the photoreceptor 3 to the intermediate transfer belt 14 . The cleaning device 6 is cleaning means for cleaning toner remaining on the photoreceptor 3 after the toner image has been transferred to the intermediate transfer belt 14 . The lubricant applicator 10 is a lubricant applicator that applies a lubricant to the surface of the photoreceptor 3 after being cleaned by the cleaning device 6 . The static elimination lamp is static elimination means for eliminating the surface potential of the photoreceptor 3 after cleaning.

The charging roller 4 is arranged in a non-contact manner with a predetermined distance from the photoreceptor 3, and charges the photoreceptor 3 to a predetermined polarity and a predetermined potential. The surface of the photoreceptor 3 uniformly charged by the charging roller 4 is irradiated with laser light L from an optical writing unit 40, which is a latent image forming means, based on image information to form an electrostatic latent image.

The developing device 5 has a developing roller 51 as a developer carrier. A developing bias is applied to the developing roller 51 from a power source. A supply screw 52 and an agitation screw 53 are provided in the casing of the developing device 5 for agitating the developer contained in the casing while transporting the developer in opposite directions. A doctor 54 for regulating the developer carried on the developing roller 51 is also provided. The toner in the developer agitated and conveyed by the two screws of the supply screw 52 and the agitation screw 53 is charged to a predetermined polarity. The developer is scooped up onto the surface of the developing roller 51 , the scooped up developer is regulated by the doctor 54 , and the toner adheres to the latent image on the photoreceptor 3 in the developing area facing the photoreceptor 3 . .

The cleaning device 6 has a fur brush 101, a cleaning blade 62, and the like. The cleaning blade 62 is in contact with the photoreceptor 3 in a direction counter to the surface moving direction of the photoreceptor 3 . Incidentally, the cleaning blade 62 is the cleaning blade in the present invention. The lubricant application device 10 includes a solid lubricant 103, a lubricant pressure spring 103a, and the like, and uses a fur brush 101 as an application brush for applying the solid lubricant 103 onto the photosensitive member 3. FIG. A solid lubricant 103 is held by a bracket 103b and is pressed toward the fur brush 101 by a lubricant pressurizing spring 103a. Then, the solid lubricant 103 is scraped by the fur brush 101 that rotates in the rotation direction with respect to the rotation direction of the photoreceptor 3 and the lubricant is applied onto the photoreceptor 3 . It is preferable that the coefficient of friction of the surface of the photoreceptor 3 is maintained at 0.2 or less during non-image formation by applying a lubricant to the photoreceptor.

The charging device of this embodiment is of a non-contact, close arrangement type in which the charging roller 4 is placed close to the photoreceptor 3. Examples of charging devices include corotrons, scorotrons, and solid state chargers. A known configuration can be used. Among these charging methods, the contact charging method or the non-contact close-positioning method is particularly preferable, and has advantages such as high charging efficiency, low ozone generation amount, and possibility of miniaturization of the apparatus.

The light source of the laser light L of the optical writing unit 40 and the light source such as the static elimination lamp include fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LED), semiconductor lasers (LD), electroluminescence (EL), ) can be used.
Moreover, various filters such as a sharp cut filter, a bandpass filter, a near-infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used in order to irradiate only light in a desired wavelength range.
Among these light sources, light-emitting diodes and semiconductor lasers are favorably used because they have high irradiation energy and long-wavelength light of 600 to 800 nm.

A transfer unit 60, which is a transfer means, includes an intermediate transfer belt 14, a belt cleaning unit 162, a first bracket 63, a second bracket 64, and the like. It also has four primary transfer rollers 7Y, C, M, K, a secondary transfer backup roller 66, a drive roller 67, an auxiliary roller 68, a tension roller 69, and the like. The intermediate transfer belt 14 is endlessly moved counterclockwise in the figure by the rotation of the drive roller 67 while being stretched around these eight roller members. The four primary transfer rollers 7Y, C, M, and K sandwich the endlessly moved intermediate transfer belt 14 between the photoreceptors 3Y, C, M, and K to form primary transfer nips. . Then, a transfer bias having a polarity opposite to that of the toner (for example, plus) is applied to the back surface of the intermediate transfer belt 14 (the inner circumferential surface of the loop). The intermediate transfer belt 14 passes through the primary transfer nips for Y, C, M, and K successively as it moves endlessly. Y, C, M, and K toner images are superimposed and primarily transferred. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the intermediate transfer belt 14 .

The secondary transfer backup roller 66 sandwiches the intermediate transfer belt 14 between itself and a secondary transfer roller 70 arranged outside the loop of the intermediate transfer belt 14 to form a secondary transfer nip. The registration roller pair 55 described above feeds the transfer paper P sandwiched between the rollers toward the secondary transfer nip at a timing that can be synchronized with the four-color toner image on the intermediate transfer belt 14 . The four-color toner image on the intermediate transfer belt 14 is affected by the secondary transfer electric field formed between the secondary transfer roller 70 to which the secondary transfer bias is applied and the secondary transfer backup roller 66 and the nip pressure. , are collectively secondarily transferred to the transfer paper P in the secondary transfer nip. Combined with the white color of the transfer paper P, a full-color toner image is formed.

Transfer residual toner that has not been transferred onto the transfer paper P adheres to the intermediate transfer belt 14 after passing through the secondary transfer nip. It is cleaned by belt cleaning unit 162 . In the belt cleaning unit 162, a belt cleaning blade 162a is brought into contact with the front surface of the intermediate transfer belt 14, thereby scraping and removing transfer residual toner on the intermediate transfer belt 14. FIG. The belt cleaning blade 162a is preferably the cleaning blade 15 of the present invention.

The first bracket 63 of the transfer unit 60 swings at a predetermined rotation angle about the rotation axis of the auxiliary roller 68 as the solenoid is turned on and off. When forming a monochrome image, the printer 500 slightly rotates the first bracket 63 counterclockwise in the drawing by driving the above-described solenoid. By this rotation, the primary transfer rollers 7Y, C, and M for Y, C, and M are revolved counterclockwise in the drawing about the rotation axis of the auxiliary roller 68, thereby rotating the intermediate transfer belt 14 to Y, C, and M. It is separated from the photoconductors 3Y, C, and M for M. Of the four image forming units 1Y, C, M, and K, only the image forming unit 1K for K is driven to form a monochrome image. As a result, it is possible to avoid wasting of each member constituting the image forming unit 1 caused by driving the image forming unit 1 for Y, C, and M unnecessarily during monochrome image formation.

A fixing unit 80 is arranged above the secondary transfer nip in the drawing. The fixing unit 80 includes a pressure heating roller 81 containing a heat source such as a halogen lamp, and a fixing belt unit 82 . The fixing belt unit 82 has a fixing belt 84 as a fixing member, a heating roller 83 including a heat source such as a halogen lamp, a tension roller 85, a driving roller 86, a temperature sensor, and the like. The endless fixing belt 84 is stretched by a heating roller 83, a tension roller 85 and a drive roller 86, and is endlessly moved counterclockwise in the figure. In the course of this endless movement, the fixing belt 84 is heated from the back side by the heating roller 83 . A pressurizing heating roller 81 rotated clockwise in the drawing abuts from the front surface side on the portion where the fixing belt 84 heated in this way is wound around the heating roller 83 . As a result, a fixing nip is formed in which the pressure heating roller 81 and the fixing belt 84 are brought into contact with each other.

A temperature sensor is arranged outside the loop of the fixing belt 84 so as to face the front surface of the fixing belt 84 with a predetermined gap therebetween. to detect. This detection result is sent to the fixing power supply circuit. The fixing power supply circuit controls on/off of power supply to the heat source included in the heating roller 83 and the heat source included in the pressure heating roller 81 based on the detection result of the temperature sensor.

After passing through the secondary transfer nip, the transfer paper P is separated from the intermediate transfer belt 14 and sent into the fixing unit 80 . In the process of being sandwiched between the fixing nip in the fixing unit 80 and conveyed from the lower side to the upper side in the figure, the full-color toner image is fixed on the transfer paper P by being heated and pressed by the fixing belt 84 . be.

The transfer paper P that has undergone the fixing process in this manner passes between the rollers of the paper discharge roller pair 87, and is then discharged outside the machine. A stack section 88 is formed on the upper surface of the housing of the main body of the printer 500 , and the transfer papers P discharged outside the machine by the pair of discharge rollers 87 are sequentially stacked on this stack section 88 .

Above the transfer unit 60, four toner cartridges 100Y, 100C, 100M and 100K containing Y, C, M and K toners are arranged. The Y, C, M, and K toners in the toner cartridges 100Y, C, M, and K are appropriately supplied to the developing devices 5Y, C, M, and K of the image forming units 1Y, C, M, and K. These toner cartridges 100Y, 100C, 100M and 100K can be attached to and detached from the printer body independently of the image forming units 1Y, 100C, 100M and 100K.

Next, an image forming operation in printer 500 will be described.
When a print execution signal is received from an operation unit or the like, predetermined voltages or currents are sequentially applied to the charging roller 4 and the developing roller 51 at predetermined timings. Similarly, predetermined voltages or currents are sequentially applied at predetermined timings to the optical writing unit 40 and the light source such as the charge removal lamp. In synchronism with this, the photoreceptor 3 is rotationally driven in the direction of the arrow in the drawing by a photoreceptor driving motor as a driving means.

When the photoreceptor 3 rotates in the direction of the arrow in the drawing, the surface of the photoreceptor 3 is first uniformly charged to a predetermined potential by the charging roller 4 . Then, the photoreceptor 3 is irradiated with a laser beam L corresponding to image information from the optical writing unit 40, and the portion irradiated with the laser beam L on the surface of the photoreceptor 3 is discharged to form an electrostatic latent image. .

The surface of the photoreceptor 3 on which the electrostatic latent image is formed is rubbed by a magnetic brush of developer formed on the developing roller 51 at the portion facing the developing device 5 . At this time, the negatively charged toner on the developing roller 51 is moved to the electrostatic latent image side by a predetermined developing bias applied to the developing roller 51 and is formed into a toner image (developed). A similar image forming process is executed in each image forming unit 1, and a toner image of each color is formed on the surface of each photoreceptor 3Y, C, M, K of each image forming unit 1Y, C, M, K. .

Thus, in the printer 500 , the electrostatic latent image formed on the photoreceptor 3 is reversely developed by the developing device 5 with negatively charged toner. In the present embodiment, an example using an N/P (negative/positive: toner adheres to low potential) non-contact charging roller system has been described, but the present invention is not limited to this.

The toner images of respective colors formed on the surfaces of the photoreceptors 3Y, C, M, and K are primary-transferred sequentially so as to overlap on the surface of the intermediate transfer belt . Thereby, a four-color toner image is formed on the intermediate transfer belt 14 .

The four-color toner image formed on the intermediate transfer belt 14 is fed from the first paper feed cassette 151 or the second paper feed cassette 152, passes between the rollers of the registration roller pair 55, and is fed to the secondary transfer nip. is transferred to the transfer paper P. At this time, the transfer paper P is temporarily stopped while sandwiched between the pair of registration rollers 55, and is supplied to the secondary transfer nip in synchronization with the leading edge of the image on the intermediate transfer belt 14. FIG. The transfer paper P onto which the toner image has been transferred is separated from the intermediate transfer belt 14 and conveyed to the fixing unit 80 . When the transfer paper P with the toner image transferred passes through the fixing unit 80, the toner image is fixed on the transfer paper P by the action of heat and pressure. 500 is ejected to the outside of the device and stacked in the stacking section 88 .

On the other hand, the belt cleaning unit 162 removes transfer residual toner on the surface of the intermediate transfer belt 14 from which the toner image has been transferred onto the transfer paper P at the secondary transfer nip.
On the surface of the photoreceptor 3 from which the toner images of each color have been transferred to the intermediate transfer belt 14 at the primary transfer nip, residual toner after transfer is removed by the cleaning device 6, and lubricant is applied by the lubricant applying device 10. After that, the charge is removed by the charge removing lamp.

As shown in FIG. 6, the image forming unit 1 of the printer 500 includes a photoreceptor 3, and a charging roller 4, a developing device 5, a cleaning device 6, a lubricant coating device 10, etc. as processing means, which are housed in a frame 2. . The image forming unit 1 is integrally detachable from the main body of the printer 500 as a process cartridge. In the printer 500, the image forming unit 1 integrally replaces the photoreceptor 3 as a process cartridge and the process means. A configuration may be adopted in which a unit such as the agent coating device 10 is replaced with a new one.

Next, toner suitable for the printer 500 to which the present invention is applied will be described.
As the toner used in the printer 500, it is preferable to use a polymerized toner produced by a suspension polymerization method, an emulsion polymerization method, or a dispersion polymerization method, which facilitates formation of high circularity and small particle size, in order to improve image quality. In particular, it is preferable to use a polymerized toner having a circularity of 0.97 or more and a volume average particle diameter of 5.5 μm or less. By using particles having an average circularity of 0.97 or more and a volume-average particle diameter of 5.5 μm, images with higher resolution can be formed.

The "circularity" referred to here is the average circularity measured by a flow type particle image analyzer FPIA-2000 (manufactured by Toa Medical Electronics Co., Ltd.). Specifically, 0.1 to 0.5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of water in a container from which impure solids have been removed in advance. ) is added about 0.1 to 0.5 g. After that, the suspension in which the toner is dispersed is subjected to dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser so that the concentration of the dispersion becomes 3000 to 1 [10,000 particles/μl]. to measure the shape and distribution of the toner. Then, based on this measurement result, the outer circumference of the actual toner projected shape shown in FIG. C2/C1 was obtained when the length was C2, and the average value was taken as the degree of circularity.

The volume average particle diameter can be determined by the Coulter Counter method. Specifically, data on the number distribution and volume distribution of toner measured by Coulter Multisizer Model 2e (manufactured by Coulter Co., Ltd.) is sent to a personal computer via an interface (manufactured by Nikkaki Co., Ltd.) for analysis.
A specific example of the analysis method will be described. A 1% NaCl aqueous solution using primary sodium chloride is prepared as an electrolytic solution. Then, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution. Further, 2 to 20 mg of toner as a sample to be tested is added to this, and dispersed by an ultrasonic disperser for about 1 to 3 minutes.
Then, 100 to 200 ml of the electrolytic aqueous solution is placed in another beaker, and the solution after the dispersion treatment is added therein so as to have a predetermined concentration, and is applied to the Coulter Multisizer 2e type.
An aperture of 100 μm is used, and the particle size of 50,000 toner particles is measured.
2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 8.00 to less than 10.08 μm; 10.08 to less than 12.70 μm; 12.70 to less than 16.00 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, using 13 channels and targeting toner particles having a particle size of 2.00 μm to 32.0 μm.

Then, the volume average particle size is calculated based on the relational expression "volume average particle size=ΣXfV/ΣfV". However, "X" is the representative diameter in each channel, "V" is the equivalent volume at the representative diameter of each channel, and "f" is the number of particles in each channel.

The present invention will be further described with reference to examples below, but the present invention is not limited to the following examples. It should be noted that Example 1 refers to Reference Example 1 that is not included in the present invention.

Examples 1-3
<Cleaning device>
A cleaning blade 15 as shown in FIG. 4 was produced.
A blade member having a two-layer structure consisting of a blade edge layer 15a-1 and a backup layer 15a-2 was adhesively fixed to an L-shaped metal blade holder 15a-3.
Both the blade edge layer 15a-1 and the backup layer 15a-2 are made of urethane resin. The JIS-A hardness of the blade edge layer 15a-1 is 64.5, and the JIS-A hardness of the backup layer 15a-2 is 74.5. It was adjusted.
The thickness of the blade edge layer 15a-1 is 0.5 mm, the thickness of the backup layer 15a-2 is 1.5 mm, and the shape of the blade member is rectangular.

<Toner>
A toner was produced according to the method described in JP-A-2014-92633.
The details of the produced toner are as follows.
・Toner base particles: average circularity 0.98, volume average particle diameter 4.9 μm
External additive: 3 parts by mass of silica particles A, silica particles B, or a mixture of silica particles A and B described below was added to 100 parts by mass of toner base particles.

Silica particles A: primary average particle size = 15 nm, secondary average particle size (equivalent to the average particle size referred to in the present invention) = 180 nm, BET specific surface area = 110 m ² /g, bulk density (ρ) = 0.44 g/ ^cm3 .
Silica particles B: primary average particle size = 80 nm, secondary average particle size (equivalent to the average particle size referred to in the present invention) = 160 nm, BET specific surface area = 35 m ² /g, bulk density (ρ) = 0.56 g/ ^cm3 .
Silica particle mixture: A mixture of the silica particles A and B at a ratio of 1:2 (mass ratio).
Bulk density (ρ) = 0.52 g/cm ³

<Assembly of Image Forming Apparatus>
Next, the prepared cleaning blade 15 is attached to a process cartridge of a color multifunction machine (imagio MP C4500, manufactured by Ricoh Co., Ltd.) (the printer section has the same configuration as the image forming apparatus 500 shown in FIG. 5), and the image forming apparatus is operated. Assembled.
The cleaning blade was attached to the image forming apparatus so as to have a cleaning angle of 88.6° and a blade bite amount of 0.65±0.15 mm.

The physical properties of the blade edge layer 15a-1 are as follows.
100% modulus (M100): 5.15 MPa
Hardness (H): 79

Using the image forming apparatus, laboratory environment: 21° C. and 65% RH, paper feeding conditions: 5% image area ratio chart was printed 3 times per job, and 50,000 sheets (A4 size landscape) were output. After passing 50,000 sheets in this manner, the following evaluations were made.

<Observation of layer of silica particles>
The layer of silica particles in the blade nip was observed under a microscope to examine the average layer thickness and coverage (C) of the silica particles.
Schematic diagrams of the results of microscopic observation of the silica particle layers in Examples 1 to 3 are shown in FIGS. 10(a) to 10(c), respectively. 10A to 10C, the top is a cross-sectional view of the cleaning blade 15, and the bottom is a top view of the blade nip 15c.

<Cleanability>
As an evaluation image, 20 sheets of a vertical band pattern (with respect to the direction of paper travel) with a width of 43 mm and 3 horizontal charts of A4 size were output, and the obtained images were visually observed. Cleanability was evaluated.

[Evaluation criteria]
⊚: The toner that has passed through due to poor cleaning cannot be visually confirmed on the printed paper or on the photoreceptor.
◯: Toner slipped through due to poor cleaning cannot be visually observed on the printed paper or on the photoreceptor.
Δ: Toner slipped through due to poor cleaning can be visually confirmed as partial spots on both the printed paper and the photoreceptor.
x: Toner passed through due to poor cleaning can be visually confirmed as a clear line on both the printed paper and the photoreceptor.

<Stability over time>
The stability over time was examined by conducting a durability run using an actual machine and comparing the timing at which the cleaning performance became Δ. Evaluation criteria are as follows.
[Evaluation criteria]
A: The average layer thickness of the silica particle layer in the blade nip is 0.1 μm or more, and the cleaning quality is A at the time of the endurance life.
◯: The average layer thickness of the silica particle layer in the blade nip is 0.1 μm or more, and the cleaning quality is ◯ at the end of the durability life.
Δ: The average layer thickness of the silica particle layer in the blade nip is 0.1 μm or less, and the cleaning quality is Δ at the end of the durability life.
x: A layer of silica particles does not exist in the blade nip, and the cleaning quality is x at the end of the service life.

The results are shown in Table 1 below.

From the results in Table 1, in Examples 1 to 3, a layer of silica particles is formed at least partially in the blade nip, and the average layer thickness of the layer of silica particles is 0.1 μm or more and 2 μm or less. It has been found that a cleaning device having a stable behavior of the cleaning blade and good cleaning performance can be provided in a small space and at a low cost.
Further, in view of the relative relationships in each example, in Example 1, silica particles A having a small primary average particle size and a high BET specific surface area were used. In the case of such silica particles A, the cohesiveness after entering the blade nip is high, and as shown in FIG. . Therefore, a very large effect of reducing the coefficient of friction was obtained, and the cleaning performance was improved. However, in Example 1, a phenomenon occurred in which the silica particles slipped through to some extent.
In Example 2, silica particles B having a large primary average particle size and a low BET specific surface area were used. Unlike Example 1, the cohesiveness is relatively low, and as shown in FIG. 10(b), the silica particles are dispersed in the blade nip to form a layer. That is, the stability over time is enhanced. However, since the silica particles have a large particle size and low adhesion to the photoreceptor, the silica particles cannot reach the downstream side in the blade nip, and the effect of reducing the frictional force is slightly reduced.
Example 3 is an example in which the small particle size silica of Example 1 and the large particle size silica of Example 2 are externally added to the toner at a ratio of 1:2. Small particle size silica accumulates while agglomerating on the upstream side of the blade nip, and when it grows to a layer thickness exceeding the secondary particle size, it progresses downstream in the blade nip, but in the middle of the blade nip Because large-particle-size silica is dispersed (unlike small-particle-size silica, it does not separate), this large-particle-size silica inhibits the progress of small-particle-size silica agglomerates in the blade nip. As a result, silica passing through the nip is reduced, and both a high layer thickness and long-term stability can be achieved. In this case, as shown in FIG. 10(c), the cross-sectional shape within the blade nip is different from that of the other examples, and the layer thickness on the upstream side within the blade nip tends to be higher than the layer thickness on the downstream side within the blade nip. was taken.
In Comparative Example 1, since the average layer thickness of the silica particle layer is less than 0.1 μm, both the cleanability and the stability over time are deteriorated.

1 Image Forming Unit 2 Frame 3 Photoreceptor 4 Charging Roller 5 Developing Device 6 Cleaning Device 7 Primary Transfer Roller 10 Lubricant Application Device 14 Intermediate Transfer Belt 15 Cleaning Blade 15a-1 Blade Edge Layer 15a-2 Backup Layer 15a-3 Blade Holder 15c Blade Nip 40 Optical Writing Unit 41 Polygon Mirror 51 Developing Roller 52 Supply Screw 53 Stirring Screw 54 Doctor 55 Registration Roller Pair 60 Transfer Unit 63 First Bracket 64 Second Bracket 66 Secondary Transfer Backup Roller 67 Drive Roller 68 Auxiliary Roller 69 TENSION ROLLER 70 SECONDARY TRANSFER ROLLER 80 FIXING UNIT 81 PRESSURE HEATING ROLLER 82 FIXING BELT UNIT 84 FIXING BELT 83 HEATING ROLLER 85 TENSION ROLLER 86 DRIVING ROLLER 87 DISCHARGE ROLLER PAIR 88 STACK UNIT 100 TONER CARTRIDGE 101 FUR BRUSH 103 SOLID LUBRICANT 103a Lubricant pressure spring 103b Bracket 123 Image carrier 151 First paper feed cassette 151a First paper feed roller 152 Second paper feed cassette 152a Second paper feed roller 153 Paper feed path 154 Conveying roller pair 162 Belt cleaning unit 162a Belt Cleaning blade 500 Image forming apparatus (printer)

JP-A-2002-6710

Claims (4)

An object to be cleaned which is a rotating body, first particles adhering to the object to be cleaned, second particles smaller in diameter than the first particles, and first particles adhering to the object to be cleaned. A cleaning device having a cleaning blade, which is a cleaning member for cleaning particles, and a blade nip, which is a contact surface between the cleaning blade and the object to be cleaned,
The second particle layer is formed in at least part of the blade nip, and the average layer thickness of the second particle layer is 0.1 μm or more and 2 μm or less, and the average layer thickness is positional. is average and
The coverage (C) of the second particle layer with respect to the area of the blade nip is 35% or more
A cleaning device characterized by: 2. A cleaning device according to claim 1 , wherein said second particles have a primary average particle size of 15 nm to 160 nm. 3. A cleaning device according to claim 1, wherein said second particles are silica particles. The cleaning device according to any one of claims 1 to 3 , wherein the object to be cleaned is a photoreceptor and/or a transfer belt.

Images