JPH04304490A - Production of developer carrying member - Google Patents

Abstract

PURPOSE:To smooth the surface of a magnetic field generating layer and to uniformize the film thickness thereof. CONSTITUTION:A stage for applying a magnetic coating material 30 by a roll coating method, then impressing a magnetic field to the applied magnetic coating material 30 is provided in the production of the developer carrying member having the magnetic field generating layer. The deterioration of the images occurring in the ruggedness and local unequal film thickness of the magnetic field generating layer of the developer carrying member is lessened in this way and the longer life of the developer carrying member is obtd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a developer carrier used in an electrophotographic developing device.

0002

[Prior Art] A conventional developer carrier, known as the one-component magnetic brush development method, has a non-magnetic cylindrical rotatable sleeve and a rotatable mag roll disposed inside the sleeve. The magnetic toner was conveyed and developed using leakage magnetic flux. However, the conventional one-component magnetic brush development method using a developer carrier has a problem in that the mag roll makes the developer carrier heavy and increases the cost.

This is an improvement on the one-component magnetic brush development method described above, and a developing device capable of forming high-quality images using a magnetic developer includes a developer carrier having at least a magnetic field generating layer. A developing device that uses a magnetic developer to develop a latent image carrier on a latent image carrier has been proposed in Japanese Patent Application No. 2-58321 and the like.

[0004] In a method of manufacturing a developer carrier used in the above-mentioned developing device, application of a magnetic paint by a roll coating method has been considered as a means for forming a magnetic field generating layer.

[0005] In the roll coating method, paints having a wide range of viscosities can be applied, and magnetic paints, which have a much higher viscosity than ordinary paints, can be easily applied. In addition, general magnetic paints exhibit thixotropy, but in the roll coating method, unlike other painting methods, there is no need to separately install a means to apply continuous shear to the paint. It is possible to apply a coating device using a roll coating method.

The magnetic field generating layer of the developer carrier used in the above-mentioned developing device has a smooth surface;
It is also desirable that the film be thin, and a roll coating method is suitable as a means for forming the magnetic field generating layer of the developer carrier used in the above-mentioned developing device.

[0007]

[Problems to be Solved by the Invention] However, when a gravure roll is used as an applicator roll in the roll coating method, fine irregularities occur on the coating surface due to the mesh engraved on the surface of the gravure roll, making it difficult to apply a smooth coating. There is a problem in that it is difficult to form a film.

[0008] Furthermore, when using a flat roll as the applicator roll, the coating nip (
At the outlet (the side where the object to be coated passes through and leaves) where the object to be coated and the applicator roll face each other and are in contact during painting, the area where the magnetic paint adheres to the object to be coated in the coating nip and the applicator When the magnetic paint is separated into parts that remain on the roll, the magnetic paint at the relevant positions tends to generate threads and mist, which causes unevenness on the surface of the paint film, making it difficult to form a paint film with a smooth surface.

Furthermore, in the roll coating method, the object to be coated and the applicator roll face each other and come into contact with each other, the paint conveyed by the applicator roll is applied to the object to be coated, and the object to be coated is separated from the applicator roll. , the coating has been completed, but when the object is separated from the applicator roll, the paint film that was applied to the object becomes locally thick only in the area that was in the coating nip. There is a problem that the thickness of the coating film becomes non-uniform. This is because when the object to be coated is being pulled away from the applicator roll, the contact pressure at the coating nip decreases rapidly, and the amount of paint transported increases rapidly. Since the accumulation flows into the coating nip section when the object to be coated is being pulled away from the applicator roll, in the coating film applied to the object to be coated, when the object to be coated is being pulled away from the applicator roll, the buildup flows into the coating nip section. The paint is applied locally and excessively only in the areas where it was present, and the paint film in those areas becomes locally thick.

In the roll coating method, when a magnetic paint is applied, the applied magnetic paint film, that is, the magnetic field generating layer, becomes uneven, making it extremely difficult to magnetize the magnetic field generating layer. This makes it extremely difficult to generate a sufficient magnetic field, leading to insufficient conveyance of the developer, resulting in problems such as blurring and other defects in the image. In addition, due to the unevenness of the magnetic field generation layer, that is, the unevenness of the film thickness, the magnetic field generated by the magnetic field generation layer becomes uneven, and the amount of developer conveyed becomes uneven, causing blurring and fading in the developed image. There is a problem that defects occur. Furthermore, due to the unevenness of the magnetic field generation layer, the developer is locally strongly rubbed,
When used for a long period of time, there is a problem in that developer filming occurs on the developer carrier.

In addition to the above, by roll coating method,
When magnetic paint is applied, there is a problem in that defects such as cracks occur in the magnetic field generation layer due to internal stress of the paint film and uneven drying in areas where the magnetic paint is applied locally in excess. In addition, the film thickness of the magnetic field generation layer is locally thick in this area, and as a result, the magnetic properties of the area are different from those of other areas, and the magnetic field generated by the magnetic field generation layer becomes non-uniform, causing developer transport. Since the amount is non-uniform, there is a problem in that defects such as blurring and fading occur in the developed image. In addition, when the latent image carrier and the developer carrier are brought into contact with each other through the developer, the contact between the developer carrier and the latent image carrier becomes unstable, resulting in defects in the image and mechanical failure of the developing device. A problem arises in that physical vibrations occur.

0012

Means for Solving the Problems The method for manufacturing a developer carrier of the present invention provides a developer carrier having at least a magnetic field generating layer, which is used in a developing device for developing a magnetic developer onto a latent image carrier. The manufacturing method is characterized in that the magnetic field generating layer is formed by at least applying a magnetic paint by a roll coating method and applying a magnetic field to the applied magnetic paint.

[0013]

[Function] According to the method for manufacturing a developer carrier of the present invention, after applying a magnetic paint by a roll coating method, a magnetic field is applied to the applied magnetic paint to form the magnetic field generating layer. The magnetic material present in the magnetic paint film applied by the coating method moves in response to the externally applied magnetic field, and as a result, the unevenness that exists on the surface of the paint film formed by the roll coating method. The surface is evened out, and the surface is smooth, and even if the thickness is uneven, the thickness is made uniform, and the coating surface is smooth, forming a thin magnetic field generation layer with a uniform thickness. It becomes possible to do so. Furthermore, since the surface of the coating film is smooth, post-processes such as polishing the surface of the coating film are not necessary.

[0014] The details of the present invention will be illustrated below with reference to Examples.

[0015]

[Example] Regarding the manufacturing method of the developer carrier of the present invention,
This will be explained based on FIG.

FIG. 1 is a schematic diagram of an embodiment of the method for manufacturing a developer carrier according to the present invention.

The coating device for the roll coating method used in this example is a general commercially available roll coater (not shown).

The object to be coated 40 is a developer carrier on which no magnetic field generating layer is formed.

Magnetic paint 30 is applied to object 40 by a roll coater.

The magnetic paint 30 is composed of a magnetic material, a resin for binding the magnetic material, and a solvent, and further contains a curing agent, an antistatic agent, a dispersant, carbon black, Ag, etc. as necessary. Conductive fine particles such as Au, Cu, and Fe are added. As the magnetic material, materials known as magnetic recording materials and magnet materials, such as Fe, Ni, Co, M
Magnetic materials containing at least one element among n, Cr, specifically γ-Fe2O3, Ba-Fe, Ni
-Co, Co-Cr, Mn-Al and the like. The resin used to bind the magnetic material includes resins known as magnetic recording materials, such as polycarbonate,
Examples include polyester, polyurethane, vinyl chloride/vinyl acetate copolymer, and the like. Examples of the solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, ethanol, butanol, toluene, xylene, water, and the like.

A magnetic field is applied to the magnetic paint 30 applied to the object 40 by the magnetic field applying means 33 constituted by the north pole magnet 31 and the south pole magnet 32 . In addition, magnetic paint 30
The coated object 40 is coated with the coated magnetic paint 30.
It rotates so that a magnetic field is applied uniformly throughout. However, the method for manufacturing a developer carrier of the present invention is not limited to the configuration of the magnetic field applying means 33 shown in FIG. 1 and the direction of the magnetic field applied to the magnetic paint 30 applied to the object to be painted 40. do not have.

The magnetic field application means 33 can start applying the magnetic field at any time before, during, or after the magnetic paint 30 is applied to the object to be coated, but it is possible to start applying the magnetic field after the application is completed. When starting, as the coating film of the magnetic paint 30 applied to the object 40 to be coated dries and hardens, it becomes difficult to smooth the surface of the coating film and make the film thickness uniform by applying a magnetic field. Therefore, it is necessary to start applying the magnetic field before the coating finishes drying and curing. Furthermore, if you start applying the magnetic field after the coating is finished, turn off the magnetic field as soon as possible after the coating is finished. Preferably, the application is started.

After the drying and curing of the coating film is completed, the effect of smoothing the surface of the coating film and making the film thickness uniform by applying the magnetic field by the magnetic field applying means 33 does not appear. It is preferable that the application ends at any point until the drying and curing of the coating film is completed.

Furthermore, before the application of the magnetic paint 30 to the object 40 is finished (the object 40 is separated from the applicator roll constituting the roll coater), the application of the magnetic field by the magnetic field applying means 33 is terminated. In this case, the magnetic field is not applied to a part of the magnetic paint 30 applied to the object to be painted 40, and the magnetic properties of the magnetic field generation layer formed by the coating film of the magnetic paint 30 applied to the object to be painted 40 are impaired. Therefore, after the application of the magnetic paint 30 to the object 40 is completed, and after applying the magnetic field uniformly to the entire magnetic paint 30 applied to the object 40, the magnetic field is applied. Preferably, the application of the magnetic field by means 33 is terminated.

When a magnetic field is applied to the magnetic paint 30 applied to the object 40 to be painted, and the magnetic paint 30 is uniformly applied to the object 40 to be painted, the magnetic paint 30 applied to the object 40 to be painted is Processes such as drying and curing of the film are performed to form a magnetic field generating layer.

FIG. 2 is a cross-sectional schematic view of a developing device that uses a developer carrier having a magnetic field generating layer formed on the surface of an elastic layer and performs development in pressure contact with a latent image carrier.

In this example, an image was formed using a developer carrier manufactured by the manufacturing method of the present invention in a developing device shown in FIG.

The developer carrier 2 conveys the magnetic toner 1.

The developer carrier 2 in this embodiment has a structure in which an elastic layer 4 is formed on the outer periphery of a base 3, and a magnetic field generating layer 6 is further formed. The base body 3 corresponds to the object to be painted 40 which is a body.
and the elastic layer 4 formed on the outer periphery thereof, which corresponds to the object 40 coated with the magnetic paint 30 in FIG. 1 is the developer carrier 2 on which the magnetic field generating layer 6 is further formed. However, the present invention is not limited to the above configuration. For example, as a coating formed on the outer periphery of the elastic layer 4 in the developer carrier 2, in addition to the magnetic field generation layer, a conductive layer, an insulating layer, etc. can be formed as appropriate.
Although the configuration of the object to be coated 40 in FIG. 1 and the configuration of the developer carrier 2 in FIG. 2 are various, it is clear that the present invention is not limited to these configurations.

As the elastic layer 4, it is possible to use known rubber, elastomer, and plastic materials that can be formed into foams. For example, natural rubber, butadiene rubber, styrene-butadiene rubber, nitrile-butadiene rubber, isoprene rubber, chloroprene rubber, silicone rubber, ethylene-propylene rubber, fluororubber, acrylic rubber, epichlorohydrin rubber, styrene resin,
It is possible to apply vinyl chloride, polyurethane, phenol resin, urea resin, epoxy resin, polyethylene, methacrylic resin, polyvinylidene fluoride, etc.

The magnetic field generating layer 6 in this embodiment has a thickness of about 1
0 μm, and the developer carrier 2 is magnetized with many poles in the circumferential direction. Its magnetic pole pitch is approximately 30 μm. Since the magnetic pole pitch is fine, the leakage magnetic flux of the magnetic field generating layer 6 rapidly decreases with increasing distance from the surface of the magnetic field generating layer 6 in the radial direction of the developer carrier 2, and only about one or two layers of toner 1 are attracted. The result is a uniform thin layer. The toner 1 held on the developer carrier 2 is further leveled evenly by a thin elastic blade 7 made of magnetic or non-magnetic metal or resin, and as the developer carrier 2 rotates, the toner 1 is spread onto the support electrode 8. The latent image carrier 10 on which the electrostatic image holding layer 9 is formed and the developer carrier 2 are conveyed to a development area where they are pressed together with the toner 1 interposed therebetween. Further, the toner 1 is applied to the latent image carrier 1
0 potential contrast and development bias application means 11
Accordingly, the support electrode 8 of the latent image carrier 10 and the developer carrier 2
The electrostatic latent image attached to the latent image carrier 10 is visualized in response to a developing electric field formed by a bias applied to the conductive layer 5 .

(Example 1) In this example, SUS
An elastic layer 4 made of conductive silicone rubber formed on the outer periphery of a base 3 formed by a manufactured shaft is used as an object 40 to be coated, and a roll coater using a natural coating method using a commercially available gravure roll as an applicator roll is used. Depending on the method of manufacturing the developer carrier,
A magnetic paint 30 whose main components are γ-Fe2O3 (magnetic material), polyurethane (binder resin), and carbon black (conductive fine particles) is applied to form a magnetic field generation layer 6, and the developer carrier 2 is prepared. did.

In this embodiment, after the application of the magnetic paint 30 was completed (the object to be coated 40 was separated from the applicator roll), a magnetic field was immediately applied by the magnetic field applying means 33 having the configuration shown in FIG. . After completing the application of the magnetic field, the coating film was dried and cured to form the magnetic field generation layer 6.

The surface of the magnetic field generating layer 6 in this example was smooth, and almost no unevenness in the thickness of the magnetic field generating layer was observed.

Furthermore, the developer carrier 2 produced in this example was used in a developing device as shown in FIG.
When a 00 DPI line latent image and a solid latent image were developed, a 600 DPI line image was formed on the latent image carrier 10 without being crushed, there was almost no background fog in the non-image area, and the optical density (OD value) was 1. It was possible to stably form a solid image with a high density of 4 or more. In this embodiment, the potential of the image area of the latent image carrier 10 is -
An electrostatic latent image with a potential of 100 V and a potential of -600 V in the non-image area was developed at a developing bias of -400 V.

Furthermore, development was repeated to form images equivalent to 1000 sheets of A4 size paper, but since the surface of the developer carrier (the magnetic field generating layer constituting it) is smooth, the surface of the developer carrier No toner filming was observed.

(Example 2) In this example, an article 4 to be coated consisting of a base 3 and an elastic layer 4 similar to Example 1 was used.
Using the same roll coater as in Example 1, the same magnetic paint 30 as in Example 1 is applied to the developer carrier according to the method of manufacturing a developer carrier of the present invention to form a magnetic field generating layer 6, Body 2 was created.

In this embodiment, application of a magnetic field is started by the same magnetic field applying means as in embodiment 1 from the middle of coating the magnetic coating material 30, and the application of the magnetic coating material 30 is completed (the object to be coated 4).
Even after the magnetic paint 30 applied to the object 40 was dried at room temperature, the magnetic field was continued to be applied. After confirming that the surface of the magnetic paint 30 applied to the object 40 had lost its tackiness, the application of the magnetic field was terminated. After the application of the magnetic field was completed, the coating film was cured by heating to form the magnetic field generation layer 6.

The surface of the magnetic field generating layer 6 in this example was smooth, and almost no unevenness in the thickness of the magnetic field generating layer was observed.

Furthermore, when the developer carrier 2 produced in this example was used in a developing device as shown in FIG. 600DPI on the image carrier 10
A line image was formed without collapse, there was almost no background fog in the non-image area, and a high-density solid image with an optical density (OD value) of 1.4 or more could be stably formed. In this example, the same developing conditions as in Example 1 were used.

[0041] Further, development was repeated to form an image equivalent to 1000 sheets of A4 size paper, but since the surface of the developer carrier (the magnetic field generating layer constituting it) is smooth, the surface of the developer carrier No toner filming was observed.

(Example 3) In this example, an object to be coated 4 consisting of a base 3 and an elastic layer 4 similar to Example 1 was used.
0, a magnetic coating material 30 similar to Example 1 was applied using a roll coater using a reverse coating method using a commercially available flat roll as an applicator roll and a magnetic coating material 30 similar to Example 1 was applied by the method for producing a developer carrier of the present invention. A generation layer 6 was formed, and a developer carrier 2 was produced.

In this example, after the application of the magnetic paint 30 was completed (the object to be coated 40 was separated from the applicator roll), a magnetic field was immediately applied by the magnetic field applying means 33 having the configuration shown in FIG. . After completing the application of the magnetic field, the coating film was dried and cured to form the magnetic field generation layer 6.

The surface of the magnetic field generating layer 6 in this example was smooth, and almost no unevenness in the thickness of the magnetic field generating layer was observed.

Furthermore, when the developer carrier 2 produced in this example was used in a developing device as shown in FIG. 600DPI on the image carrier 10
A line image was formed without collapse, there was almost no background fog in the non-image area, and a high-density solid image with an optical density (OD value) of 1.4 or more could be stably formed. In this example, the same developing conditions as in Example 1 were used.

[0046] Further, development was repeated to form an image equivalent to 1000 sheets of A4 size paper, but since the surface of the developer carrier (the magnetic field generating layer constituting it) is smooth, the surface of the developer carrier No toner filming was observed.

(Comparative Example 1) In this comparative example, the magnetic field applying means 3, which is a feature of the method for manufacturing a developer carrier of the present invention, was
The same magnetic paint as in Example 1 was coated on the same substrate 3 and elastic layer 4 as in Example 1 using the roll coater used in Example 1 without applying the magnetic field as in Example 3. As a result, the surface of the magnetic paint 30 applied to the object 40 has the following properties:
Irregularities were generated due to the mesh engraved on the gravure roll, and the magnetic paint 30 was locally and excessively applied to the position that was in the coating nip when coating was completed.

The coating film of the magnetic paint 30 applied to the object to be coated 40 is dried and cured to form the magnetic field generating layer 6,
When the developer carrier 2 was manufactured, it was found that the surface of the magnetic field generating layer 6 was uneven and had poor surface smoothness. The film thickness of the magnetic field generating layer 6 was locally thick, and cracks in the magnetic field generating layer 6 were observed in these areas.

Developer carrier 2 produced in this comparative example
When a line latent image and a solid latent image of 600 DPI were developed by using the developing device as shown in FIG. 2 in the same manner as in Example 1, the area where the magnetic paint was locally applied excessively and the area before and after it were detected. In this case, the contact state between the developer carrier 2 and the latent image carrier 10 becomes unstable, and on the latent image carrier 10, line images are crushed, background fog in non-image areas, and solid images are blurred. Also, the vibration of the developing device was large, making it impossible to form images stably.

Furthermore, when development was repeated to form images equivalent to 50 sheets of A4 size paper, toner filming occurred on the surface of the developer carrier 2, and localized excessive magnetic Cracking and peeling of the magnetic field generation layer occurred in the area where the paint was applied and the areas before and after it.

(Comparative Example 2) In this comparative example, the same magnetic paint as in Example 1 was applied to the substrate 3 and elastic layer 4 as in Example 1 using the roll coater used in Example 3.

As a result, unevenness occurs on the surface of the coating film of the magnetic paint 30 applied to the object to be painted 40 due to the magnetic paint that has become string and mist at the exit of the coating nip.
Moreover, the magnetic paint 30 was locally applied in excess at the position that was in the coating nip when the coating was completed.

When the coating film of the magnetic paint 30 applied to the object to be coated 40 was dried and cured, the surface of the coating film was uneven and the surface smoothness was poor. In areas where the coating was applied locally in excess, the coating film was locally thick and cracks were observed in those areas.

A magnetic field was applied to the coating film of the magnetic paint 30 described above in the same manner as in Example 1 to form the magnetic field generating layer 6, and the developer carrier 2 was prepared. Regarding the thick film, no change was observed compared to before the application of the magnetic field.

Developer carrier 2 produced in this comparative example
When a line latent image and a solid latent image of 600 DPI were developed by using the developing device as shown in FIG. 2 in the same manner as in Example 1, the area where the magnetic paint was locally applied excessively and the area before and after it were detected. In this case, the contact state between the developer carrier 2 and the latent image carrier 10 becomes unstable, and on the latent image carrier 10, line images are crushed, background fog in non-image areas, and solid images are blurred. Also, the vibration of the developing device was large, making it impossible to form images stably.

Furthermore, when development was repeated to form an image equivalent to 50 sheets of A4 size paper, toner filming occurred on the surface of the developer carrier 2, and localized excessive magnetic Cracking and peeling of the magnetic field generation layer occurred in the area where the paint was applied and the areas before and after it.

Although the embodiments have been described above, the present invention is applicable not only to the above embodiments, but also to a wide range of methods for manufacturing developer carriers in developing devices such as electrophotography, particularly in developing devices such as printers, copying machines, and facsimile machines. Can be applied.

[0058]

As described above, in the method of manufacturing a developer carrier having at least a magnetic field generating layer according to the present invention, it is extremely easy to control the thickness of the magnetic field generating layer, and a very uniform magnetic field can be generated. Since it is possible to form a magnetic field generation layer with a smooth surface only by the coating process, it is possible to manufacture a long-life developer carrier. Since there is no need for smoothing treatment such as surface polishing as a post-process, it is possible to produce a large amount of developer carrier (magnetic field generation layer) in an extremely short time compared to other coating methods. In addition, it is a simple process, the scale of the equipment is small, and the painting process does not waste paint, so it has the effect of being low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of a method for manufacturing a developer carrier according to the present invention.

FIG. 2 is a cross-sectional schematic view of an embodiment of a developing device using a developer carrier according to the present invention.

[Explanation of symbols]

1 Toner 2 Developer carrier 3 Base 4 Elastic layer 6 Magnetic field generation layer 10 Latent image carrier 30 Magnetic paint 31 Magnet N pole 32 Magnet S pole 33 Magnetic field application means 40 Object to be painted

Claims (1)

[Claims] 1. A method for manufacturing a developer carrier having at least a magnetic field generating layer, which is used in a developing device for developing a latent image carrier with a magnetic developer, comprising at least applying a magnetic paint by a roll coating method. A method for manufacturing a developer carrier, characterized in that the magnetic field generating layer is formed by applying a magnetic field to the applied magnetic paint.