JPH0427981A - Developer carrying member - Google Patents

Abstract

PURPOSE:To obtain the stable adhesion and electrostatic charge quantity of toners and to obtain high-quality copied images by making conductor parts and dielectric parts to coexist in microareas on the surface of the developer carrying member and incorporating a material having specific Vickers hardness in either thereof. CONSTITUTION:The developer carrying members are so constituted that the conductor parts and the dielectric parts coexist in the microareas on its surface. The material having >=100kg/mm<2> Vickers hardness is incorporated into at least either of the conductor parts or the dielectric parts. Since the many micro- closed electric fields are formed near the surface of the developer carrying member, the electric field intensity thereof is made much higher than heretofore and the friction characteristics of the developer carrying member surface are improved. The wear resistance is thus greatly improved. A large quantity of the sufficiently electrostatically charged nonmagnetic toners are deposited on the developer carrying member and transported to a developing region stably over a long period of time, by which the high-quality copied images are obtd.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention supplies a non-magnetic one-component developer to which an adjuvant is externally added as necessary to a rotationally driven developer carrier. The developer is carried on the surface of a developer carrier, and the electrostatic latent image formed on the latent image carrier is transferred to a development area where the latent image carrier and the developer carrier face each other. The present invention relates to a developer carrier used in an image forming method in which an image is visualized by the developer carried on the developer carrier.

[Conventional technology]

Image forming devices such as electronic copying machines, printers, and facsimile machines that form an electrostatic latent image on a latent image carrier and visualize it with a developer to obtain a recorded image use a dry type that uses a powdered developer. This developing device is widely used.

As such powder-like developers, two-component developers containing toner and carrier and one-component developers that do not contain carrier are known, and two-component developers using the former two-component developer are known. Although this method allows relatively stable and good recorded images to be obtained, carrier deterioration and toner-to-carrier mixing ratio fluctuations are likely to occur, the maintenance and management of the device is complicated, and the overall structure of the device tends to increase in size. It has its drawbacks.

From this point of view, a one-component development system using a one-component developer that does not have the above-mentioned drawbacks is attracting attention. - Component type developers include those consisting only of toner and those consisting of a mixture of toner and an auxiliary agent, to which an auxiliary agent is externally added as required. Toners include magnetic toner, in which each toner particle itself contains magnetic powder, and non-magnetic toner, which does not contain magnetic material.

Here, since magnetic materials are generally opaque, when a full-color or multi-color image is formed using magnetic toner, the developed visible image becomes unclear, making it impossible to obtain a vivid color image. Therefore, especially for color development, it is desirable to adopt a one-component development method using non-magnetic toner.

By the way, in a developing device that employs a -component development method, a -component developer is carried on a developer carrier and transported, and in a development area where the developer carrier and the latent image carrier face each other, The electrostatic latent image formed on the latent image carrier is made into a visible image using a developer, but in order to form a high-quality visible image with a predetermined density, a large amount of sufficiently charged toner must be applied to the development area. It is necessary to convey the latent image and visualize the latent image using the toner.

When magnetic toner is used, the one-component developer can be carried on the developer carrier by utilizing the magnetic force of the magnet inside the developer carrier, so the above requirements can be met relatively easily. is possible.

However, when a non-magnetic one-component developer is used, it is difficult to satisfy the above requirements because it cannot be supported on a developer carrier by magnetic force. Various countermeasures against this problem have been proposed in the past. For example, in Japanese Patent Laid-Open No. 61-42672, a layer of dielectric material (insulator) is laminated on the surface of the developer carrier (developing roller). 1. A developer supplying member made of, for example, a sponge roller is brought into pressure contact with the dielectric material, and both are frictionally charged to opposite polarities, and non-magnetic toner charged to the opposite polarity to the dielectric material is electrostatically attached to the dielectric material. A method of transporting such a -component developer to a development area has been proposed. However, even with this method, it is not possible to sufficiently increase the strength of the electric field formed near the dielectric surface, so it is difficult to carry a large amount of toner on the surface of the developing roller. Due to insufficient amount of toner, it is difficult to form a high-density visible image. A configuration in which an electric field is applied is also known, but even if such a configuration is added, it is difficult to attach a sufficient amount of toner to the developing roller.

Nao, as a toner supply member, 1oζ1o-・clll
conductive foam (Japanese Unexamined Patent Publication No. 60-229057),
Elastic body with skin layer (Japanese Unexamined Patent Publication No. 60-229060)
It has been proposed to use a fur brush (Japanese Unexamined Patent Publication No. 61-42672), and as a developing roller.

Metal body with uneven surface (Japanese Unexamined Patent Publication No. 60-53976), integrated insulating coated roller (time open! @ 55-4676)
No. 8) Medium and low antibody coated roller (Japanese Patent Application Laid-Open No. 58-1327
8) and an electrode roller having an insulator and a conductive surface (Japanese Unexamined Patent Publication No. 53-36245).

Furthermore, in a developing device using a non-magnetic component developer,
In Japanese Patent Application Laid-Open No. 60-229057, a sponge roller,
JP-A No. 62-229060 uses an elastic roller, and JP-A No. 61-52663 uses a fur brush or the like to apply an electric charge to the toner through frictional charging between the toner and a replenishing member, and furthermore, by contact with a developing roller. Friction causes the toner to electrostatically adhere to the developing roller, and a layer thickness regulating member such as a blade is used to control the toner layer to develop the latent image on the photoreceptor. Various materials are used for the developing roller, such as insulating materials, medium resistance materials, and laminated materials.

According to the methods shown in these references, toner adhesion to the developing roller is achieved by frictional electrification between the toner replenishing member and the developing roller, but sufficient electrification cannot be achieved due to friction between the toner-attached member. This results in insufficient toner adhesion. The optimum adhesion amount and charge amount in the non-magnetic component development method will be explained as follows.

For black and white, emphasis is placed on the amount of charge, which is generally 10~
It is 20μC/g. If the value is smaller than this value, the image quality will be poor in terms of background stains, sharpness, etc.

Regarding the amount of adhesion, the amount of adhesion on the developing roller is 0.
1-0.3+ag/cm2, but 0.3+ag/cm2 on the transfer paper.
4-0.5B/c2 is required, and the amount of toner adhesion is covered by making the speed of the developing roller 3 to 4 times the speed of the photoreceptor. However, when the developing roller rotates 3 to 4 times faster, there is a problem in that the phenomenon of ``toner from the rear edge'' occurs, that is, when a solid area is developed, the density at the rear edge of the image becomes higher. be.

To prevent this phenomenon, the speed of the developing roller should be made close to the speed of the photoreceptor. In other words, it is necessary to increase the amount of toner deposited on the developing roller and reduce the number of rotations.

On the other hand, color toner has a lower degree of coloring than black toner, and when trying to improve the toner's trailing edge, O08-1, 2 is even more concentrated than black toner.
An amount of adhesion on the developing roller of "B/am" is required.

In addition, regarding the amount of charge, in order to obtain a stable image, 5 to 20 μC/g (preferably 10 to 15 μC/g)
A value of is desired.

As a method to solve these problems, the present inventors
First, a one-component developer consisting of a non-magnetic toner to which an adjuvant is externally added as necessary is supplied to a rotationally driven developer carrier, and the developer is carried on the surface of the carrier. In a developing area where the latent image carrier and the developer carrier face each other, the electrostatic latent image formed on the latent image carrier is made visible by the developer carried on the developer carrier. In the developing method for image formation, a large number of minute electric fields are formed near the surface of the developer carrier by selectively holding charges on the surface of the developer carrier, and the charged toner is attracted by the closed electric field, The developer is attached and supported on the surface of the developer carrier,
We proposed an image forming method in which an electrostatic latent image is visualized using the developer carried thereon.

In this method, a large number of microfields are formed near the surface of the developer carrier, so the field strength can be significantly increased compared to the conventional method, and a large amount of sufficiently charged non-magnetic This has many advantages, such as being able to carry toner on a developer carrier and transport it to a developing area.

[Problem to be solved by the invention]

However, even in the image forming method in which a large number of microfields are formed near the surface of the developer carrier as described above, there are many members on the developer carrier, such as a toner supply member, a toner layer thickness regulating member, During contact development, the photoreceptor and the like are in contact with each other, and when the developing device is opened, the developer carrier slides against each of the above-mentioned members.

If the surface of the developer carrier is heavily worn, repeated use over a long period of time will cause changes in the contact pressure with each contact member, especially the toner layer thickness regulating member, making it difficult to obtain the desired toner adhesion amount and toner charge amount. In addition, the surface smoothness of the dielectric portion and the conductive portion is impaired, resulting in unevenness in one image, uneven density, and the like.

Therefore, an object of the present invention is to improve durability such as abrasion resistance, obtain stable toner adhesion amount and toner charge amount even after long-term use, and produce high-quality copied images in the image forming method described above. The object of the present invention is to provide a developer carrier that provides the following properties.

[Means to solve the problem]

As a result of intensive study, the present inventors found that at least one of the dielectric part and the conductive part has a Vickers hardness of 100 kg/
The present inventors discovered that a developer carrier containing a material with a diameter of 1 mm or more is suitable for the above purpose, and completed the present invention.

That is, according to the present invention, on the surface of the developer carrier,
By selectively retaining electric charge, a large number of minute electric fields are formed near the surface of the developer carrier, and a non-magnetic film made of toner to which an auxiliary agent is externally added as necessary is placed on the developer carrier. A developer carrier used in an image forming method in which a component-based developer is supplied, the developer is carried on the surface of the developer carrier by the minute electric field, and an electrostatic latent image is visualized by the carried developer. It is characterized in that a conductor part and a dielectric part are mixed in a small area on the surface thereof, and at least one of these parts contains a material having a Vickers hardness of 100 kg/mm or more. A developer carrier is provided.

In the image forming method using the developer carrier of the present invention, a large number of minute closed electric fields are formed near the surface of the developer carrier, so the electric field strength can be significantly increased compared to the conventional method. Because at least one of the body portion or the conductor portion is made of a material with a Vickers hardness of 100 kg/+am” or more, wear resistance is improved, and as a result, it is stable for a long period of time, and a large amount of sufficiently charged non-magnetic toner can be produced. It can be carried on a developer carrier and transported to a developing area, giving high quality copied images.

This image forming method will be explained below.

FIG. 1 shows an outline of a typical developing device useful for carrying out this image forming method, centering on the developer carrier section. In FIG. 1, the toner 6 contained in the toner tank 7o
0 is a toner supply member (sponge roller, fur brush, etc.) 4 by a stirring blade (toner supply auxiliary member) 50.
0, the toner 60 is forcibly brought to the toner supply member 4
o. On the other hand, the developer carrier (developing roller) 20 of the present invention, which has completed the development, rotates in the direction of the arrow (for example, 400 rpm) L/, and reaches the contact portion with the toner supply member 40 . The toner supply member 40 rotates in the opposite direction to the developer carrier 20 (for example, at 300 rpm) L, charges the developer carrier 20 and the toner 60, and causes the toner 60 to adhere to the developer carrier 20.

Further, the developer carrier 20 rotates, and the toner adhering to the developer carrier 20 is removed by the toner layer thickness regulating member (elastic blade) 3.
0, the charging is stabilized while the thickness is controlled, and the developing area 80 is reached. In the development area 80, the latent image is developed by contact or non-contact development. Here, if necessary, direct current may be applied to the developer carrier 20 and the toner supply member 40.
The optimal image can be controlled by applying bias such as alternating current, direct current superimposed alternating current, and pulses.

Next, the mechanism of toner adhesion to this type (electrode type) developer carrier 20 will be explained.

As an example of the developer carrier 20, as shown in FIG. 2, the developer carrier 20 is configured such that a dielectric portion and a conductive portion coexist in a small area on its surface.

The size of the area is, if the shape is circular, the diameter is 1
Minute areas ranging in size from 0 to 500 are distributed randomly or according to a certain rule. As for the area ratio, the area of the insulating portion is preferably in the range of 20 to 60%.

Toner adhesion is as follows. First, the developer carrier 20 that has completed development rotates in the direction of the arrow and comes into contact with the toner supply member 40 . The remaining toner in the non-image area that has not been developed is mechanically and electrically scraped off by the toner supply member 4o, and the dielectric portion is charged by friction. At this time, the charges on the developer carrier 20 and toner due to the previous development are as follows:
The toner carried by the supply member 4o is made constant and initialized by friction, and then the toner is charged by friction and electrostatically adheres to the dielectric portion of the developer carrier 20. At this time, the polarity of the toner is opposite to the charge on the photoreceptor, and the dielectric portion of the developer carrier 20 is of the same polarity.

At this time, the electric field on the developer carrier 20 becomes a microfield (closed electric field) as shown in FIG. 2, and becomes an electric field with a large electric field gradient, making it possible to adhere the toner in multiple layers. Further, since the adhered toner is in a closed electric field, it is strongly attracted to the developer carrier 20 side and becomes difficult to separate.

The thickness of this toner layer is further controlled by a toner layer thickness regulating member 30, and the toner layer reaches the development area 80.

The developer carrier 20 and the electrostatic latent image carrier (
The electric field between the photoconductors 10 has a large electrode effect, and the toner on the developer carrier 20 easily adheres to the electrostatic latent image carrier 10, thereby performing development.

Next, one developer carrier of the present invention will be explained.

As described above, the developer carrier of the present invention is characterized in that at least one of the dielectric portion and the conductive portion on the surface thereof contains a material having a Vickers hardness of 100 kg 10+++” or more.

Materials with a Vickers hardness of 100 kg/m2 or more include various metals, alloys, and 1120. , AQ20
3-TiO,, TiO2, Cr, O, -i, o, -5i
O2, TiN, Si3N,.

Examples include ceramics such as SiC.

According to the research conducted by the present inventors, at least one of the dielectric part and the conductive part has a Vickers hardness of 100 kg/m.
It has been found that the inclusion of a material with a diameter of u'' or more improves the frictional characteristics of the surface of the developer carrier and significantly improves the abrasion resistance.

In the present invention, the basic materials used as the dielectric material constituting the developer carrier include alkyd resin, chlorinated polyether, chlorinated polyethylene, epoxy resin, fluororesin, phenol resin, polyamide, polycarbonate, polyethylene, methacrylic resin, Resins such as polypropylene, polystyrene, polyurethane, polyvinyl chloride, polyvinylidene chloride, silicone resin, butadiene rubber, styrene-butadiene rubber, ethylene propylene rubber, chloroprene rubber, chlorinated polyethylene, epichlorohydrin rubber, nitrile rubber, acrylic rubber, silicone rubber , fluororubber and other rubbers, but silicone resins and fluororesins are preferably used from the viewpoint of heat resistance and moisture resistance.

At least a part of the surface of the dielectric part has a Vickers hardness of 1
In order to create a structure with a hardness of 00 kg/m2 or more, metals, alloys, and ceramics having a Vickers hardness of 100 kg/m12 or more can be incorporated into the basic material used as the dielectric material as described above. good.

In addition, in order to create a structure in which at least a part of the surface of the conductor part has a Vickers hardness of 100 kg/mm2 or more, a metal, alloy, ceramic, etc. having a Vickers hardness of 100 kg/mm2 or more is used as the core of the developer carrier. Alternatively, conductive particles such as carbon or metal particles are added to the resin or rubber exemplified as the dielectric material to make it conductive, and the Vickers hardness is 100K.
A method is adopted in which a material containing ceramics of g/am2 or more is used as the core metal material.

In order to produce the developer carrier of the present invention, for example, (A)
(i) First, a metal roller with a Vickers hardness of 100 kg/l 11 m" or more, whose surface is grooved by fleur-de-lis knurling or the like, is prepared. In this case, the grooves are 0.1 to 0.
5 pitch, approximately 45° to the longitudinal direction of the roller.
(see Figure 3(a)), (iii
Next, the dielectric material is coated on the grooved metal surface by spraying, dipping, etc., and cured and dried under predetermined conditions until the coating thickness is adjusted so that the grooves are completely filled. Figure 3 (b)], (■) Next, the surface of the roller is cut or polished so that the conductive surface and dielectric surface are mixed in a small area, and the conductive part area is 20.
The method is to shave down to ~60% [see Figure 3 (C)].

(B) (iv) First, a metal roller whose surface is grooved by fleur-de-lis knurling etc. is prepared. In this case,
The grooves have a pitch of 0.1 to 0.5 mm, and are machined at an angle of approximately 45° to the longitudinal direction of the roller.) [See Figure 3 (
a)], (V) Next, a dielectric material containing a material with a Vickers hardness of 100 kg/mm" or more is coated on the V-grooved metal surface by a method such as spraying or dipping, and cured under predetermined conditions. Make sure the coating is dry and thick enough to completely fill the V-groove) [See Figure 3 (b)
)], (vi) Next, the surface of the roller is cut or polished so that the conductive surface and dielectric surface are mixed in a small area, and the area of the conductive part is reduced to 20 to 60% [see;
The method shown in FIG. 3(C) is adopted.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that parts represent parts by weight.

Example 1 Coronate EH (50 xylene solution) 2
0 parts toluene 10
0 parts xylene 100
A developer carrier (developing roller) was prepared in the following manner using the materials with the above formulation.

(i) Grooves were formed on the surface of a metal roller made of steel with a Pinkers hardness of 600 kg/am by fleur-de-lis knurling. The grooves had a pitch of 0.2 mm and were formed at approximately 45 degrees to the longitudinal direction of the roller.

(ii) The V-grooved roller surface was coated with the above dielectric material, and cured and dried at 100° C. for 71 hours. The coating thickness was such that the grooves were completely filled.

(iii) The surface of the roller was polished so that a conductive surface and a dielectric surface coexisted in a small area, so that the conductive part area was 50%.

Example 2 Conductive primer (manufactured by Toray Silicone Co., Ltd. = DY39)
The following roller-forming components were press-molded onto the core bar coated with 200° C.-011) under the following conditions: primary vulcanization: 170° C. for 710 minutes, 120 kg/cm” secondary vulcanization: 200° C. for 74 hours.

C roller forming components] Methyl vinyl polysiloxane 100 parts Carbon (Ketchen Black EC) 5 parts Quartz
20 parts PZT (52/48) (Jumin Cement Co., Ltd.)
100 parts xane; Toray Silicone Co., Ltd.) After molding the above mixture with two rolls, the surface is polished so that dielectric parts and conductive parts made of ceramic (PZT) coexist to form the developer carrier of the present invention (developing material). roller)
was created.

Note that PZT is a ceramic fine particle having a Vickers hardness of 1320 kg/mm.

Comparative Example Conductive primer (manufactured by Toray Silicone Co., Ltd.: DY39)
Primary vulcanization of the following roller forming components onto the core bar coated with -011): 170°C, 710 minutes, 120kg/ca+”2
Post-vulcanization: Press molding was performed at 200° C. for 74 hours.

[Roller forming component]

Methyl vinyl polysiloxane 100 parts Carbon (Ketchen Black EC) 5 parts Quartz
20 parts The above mixture was kneaded with two rolls. After molding, the same V grooves as in Example 1 were formed by fleur-de-lis knurling. 6 Then, the dielectric material used in Example 1 was coated on the grooved surface. A developing roller for comparison was then produced in the same manner as in Example 1.

〔evaluation〕

Toner, Amount of Amount, and Charge Amount Each developing roller was attached to the developing device shown in FIG. 1, and the amount of toner adhering to the roller and the amount of toner charge on the roller were measured after 10 rotations of the developing roller and after copying 10,000 sheets.

The results are shown in Table 1.

In the above-mentioned developing device, the toner layer thickness regulating member was made of urethane rubber, the toner supply member was made of conductive urethane sponge, and positively charged toner was loaded.

Abrasion of Image Roller Using the same developing device and toner as described above, the amount of wear of each developing roller after running idly for 2 DEG hours was measured by measuring the diameter of the developing roller. The diameter of the roller was measured using a laser micro gauge (DT-4002A; manufactured by Iwatsu Electronics Co., Ltd.).

The results are shown in Table 1.

11 Yield: Images obtained by copying 10,000 sheets using the same developing device and toner as described above were visually evaluated.

From the results in Table 1, it can be seen that by using the developing roller of the present invention, sufficient toner adhesion and toner charge amount can be obtained, the abrasion of the developing roller can be reduced, and high quality images can be obtained. I understand.

〔Effect of the invention〕

The developer carrier of the present invention has a structure in which a conductor part and a dielectric part coexist in a small area on the surface thereof, and at least one of them contains a material having a Vickers hardness of 100 kg/c112 or more. Therefore, by selectively holding charges on the surface of the developer carrier, a large number of minute electric fields are formed near the surface of the developer carrier.
A non-magnetic one-component developer made of toner to which an auxiliary agent is externally added as necessary is supplied onto the developer carrier, and the developer is supported on the surface of the developer carrier by the minute electric field. When the developer carrier of the present invention is used in an image forming method in which an electrostatic latent image is visualized using the developer carrier, a large amount of sufficiently charged non-magnetic one-component developer can be transferred to the developer carrier. It can be carried and conveyed to the developing area, and the sliding force with other contact members can be alleviated, improving abrasion resistance, that is, durability.

As a result, high-density, high-quality images can be stably obtained over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view centered on a developer carrier portion showing an example of a developing device in which a microfield electric field is formed on a developer carrier useful for carrying out the present invention. Also,
FIG. 2 is a schematic cross-sectional view for explaining a state in which a closed electric field is generated by a microfield on a developer carrier in the apparatus shown in FIG. Furthermore, FIGS. 3(a) to 3(C) are schematic cross-sectional views showing the surface state during the manufacturing process of the developer carrier of the present invention. 10... Electrostatic latent image carrier, 20... Developer carrier,
30... Toner layer thickness regulating member, 40... Toner supply member, 50... Stirring blade, 60... Toner, 70...
...Toner tank, 80...Development area.

Claims (1)

[Claims] (1) By selectively retaining electric charges on the surface of the developer carrier, a large number of minute closed electric fields are formed near the surface of the developer carrier, and as needed, A non-magnetic one-component developer made of toner externally added with an adjuvant is supplied, the developer is supported on the surface of the developer carrier by the minute closed electric field, and the electrostatic latent image is made visible by the supported developer. A developer carrier used in an image forming method, in which a conductor part and a dielectric part are mixed in a small area on the surface thereof, and at least one of these parts has a Vickers hardness of 100 kg/mm^2 or more. A developer carrier characterized in that it contains a material.