JPH0442177A - Developer carrier - Google Patents

Abstract

PURPOSE:To secure stable toner sticking quantities and toner electrostatic charging quantities for various dielectric materials by incorporating an electrostatic charging control agent in either or both of a dielectric part and a conduction part. CONSTITUTION:The developer carrier 20 has the electrostatic charging control agent incorporated in the dielectric part or (/and) conduction part. This constitution increases the controllability of the electrostatic charging of toner carried by a toner supply member 40 to secure the sufficient toner sticking quantity and toner electrostatic charging quantity, and consequently stableness is obtained for a long period; and much nonmagnetic toner 60 which is charged sufficiently can be carried on the developer carrier 20 and conveyed to a development area.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention supplies a non-magnetic one-component developer to which an auxiliary agent is externally added as necessary to a rotating developer carrier, The developer is carried and conveyed on the surface of the developer carrier, and an electrostatic latent image is formed on the latent image carrier in 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 for visualizing images using 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. Furthermore, toners include magnetic toners in which magnetic powder is kneaded into each toner particle itself, and non-magnetic toners that do 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 employing 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). A developer supply member made of, for example, a sponge roller is brought into pressure contact with the dielectric material, and the two 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 the insufficient amount of agent, it is difficult to form a high-density visible image.

Furthermore, a configuration is also known in which an electric field is applied between the developing roller and the developer supply member in a direction in which the non-magnetic toner electrostatically moves toward the developing roller, but even if such a configuration is added, It is difficult to make a sufficient amount of toner adhere to the developing roller.

In addition, as a toner supply member, 102 to 106 Ω・C
11 conductive foam (Japanese Unexamined Patent Publication No. 60-229057), elastic body with skin layer (Unexamined Japanese Patent Application No. 60-229060), fur brush (Unexamined Japanese Patent Application No. 61-42672), etc. has been proposed, and as a developing roller.

Metal body with uneven surface (Japanese Unexamined Patent Publication No. 60-53976), integral insulated roller (Unexamined Japanese Patent Application No. 55-46768)
Publication) Medium and low antibody coated roller (Japanese Patent Application Laid-Open No. 58-13278
JP-A-53-36245) and an electrode roller having an insulator and a conductive surface (JP-A-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. The toner is electrostatically adhered to the developing roller by friction at the toner, and a layer thickness regulating member such as a plate 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.
1-0.3mg/ca+2, but 0.3mg/ca+2 on the transfer paper.
4-0.5 mg/cm2 is required, and the amount of toner adhesion is covered by increasing the speed of the developing roller to 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 trailing edge" occurs, that is, when a solid area is developed, the density at the trailing edge of one 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 smaller degree of coloring compared to black toner, and if you try to improve the "from the rear end of the toner", the degree of coloring will be even higher than that of black toner, from 0.8 to 1,2.
An amount of adhesion on the developing roller of mg/am2 is required. Regarding the amount of charge, in order to obtain a stable image, the amount of charge should be 5 to 20 μC/g (preferably 10 to 15 μC/g).
g) 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 auxiliary agent has been externally added as necessary is supplied to a rotating 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 transferred by the developer carried by the developer carrier. In the visual development method, 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 1. The charged toner is attracted by this closed electric field. The authors proposed an image forming method in which a developer is attached to and carried on the surface of a developer carrier, and an electrostatic latent image is visualized by the carried developer.

In this invention, since a large number of microfields are formed near the surface of the developer carrier, the electric field strength can be significantly increased compared to the conventional method, and a large amount of charged non-magnetic toner can be removed. It has many advantages such as being able to be carried on a developer carrier and transported to a developing area.

[Problem to be solved by the invention]

However, even in the above-described image forming method in which a large number of microfields are formed near the surface of the developer carrier, other properties necessary for the developer carrier, such as toner releasability, low coefficient of friction, and durability, are required. When various materials are used as dielectrics in order to satisfy abrasion resistance, etc., there is a problem in that triboelectric charging characteristics vary widely. That is, it is very difficult to simultaneously satisfy the desired toner adhesion amount, toner charge amount, and other characteristics.

Therefore, an object of the present invention is to arbitrarily control the triboelectric charging characteristics of the toner in the above-mentioned image forming method.
It is an object of the present invention to provide a developer carrier capable of ensuring stable toner adhesion amount and toner charge amount for various dielectric materials.

[Means to solve the problem]

As a result of intensive study, the inventors found that the dielectric part or (and)
The present inventors have discovered that a developer carrier containing a charge control agent in a conductive portion is suitable for the above purpose, and have completed the present invention.

That is, according to the present invention, on the surface of the developer carrier,
By selectively retaining charge.

A large number of minute electric fields are formed near the surface of the developer carrier, and 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. slight t
J＼A developer carrier used in an image forming method in which the developer is supported on the surface of the developer carrier by a closed electric field and an electrostatic latent image is visualized by the carried developer, the developer carrier having a dielectric layer on its surface. A developer carrier is provided, characterized in that a conductive part and a conductive part are mixed in a small area, and a charge control agent is contained in either or both of the M-shaped part and the conductive part. Ru.

In the image forming method using the developer carrier of the present invention, since a large number of minute closed electric fields are formed near the surface of the developer carrier, the electric field strength can be significantly increased compared to the conventional method. Since the developer carrier has a structure in which a charge control agent is contained in the dielectric part or (and) the conductive part, the controllability of toner charge is increased and a sufficient amount of toner adhesion and toner charge is ensured. As a result, a large amount of sufficiently charged non-magnetic toner can be carried on the developer carrier and transported to the development area stably for a long period of time.

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, toner 6 contained in a toner tank 70 is shown.
0 is a toner supply member (sponge roller, fur brush, etc.) 4 by a stirring blade (toner supply auxiliary member) 50.
Forced to 0.

Toner 60 is supplied to toner supply member 40 . on the other hand,
Developer carrier (developing roller) 2 of the present invention that has completed development
0 is rotation in the direction of the arrow (for example, 40 Orpm) L,
The contact portion with the toner supply member 40 is reached. The toner supply member 40 rotates in the opposite direction to the developer carrier 20 (for example, 300
rpm) L, the developer carrier 20 and the toner 60 are charged, and the toner 60 is deposited on 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, since the thickness is not controlled, the charging is stabilized 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 2o, as shown in FIG. 2, for example, the developer carrier 2o is configured such that a dielectric portion and a conductive portion coexist in a small area on its surface. Assuming that the area is circular, minute areas with a diameter of 10 to 500 pm are distributed randomly or according to a certain rule. As for the area ratio, the area of the conductor part is 2
A range of 0 to 60% is preferred.

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 40, 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:
It is stabilized and initialized by friction. Next, the toner carried by the supply member 4Q 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.

Further, the electric field on the developer carrier 20 at this time becomes a micro field (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. Become. 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 1o, thereby performing development.

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

As described above, the developer carrier of the present invention has a structure in which dielectric portions and conductive portions are mixed in a small area on the surface thereof. In addition to the V-groove type roller shown in Figure 2, the rollers shown in Figures 3 (a) and (b)
The following can be mentioned.

Any insulating material can be used as the material for the dielectric portion. However, 1012Ω・cff1 or more.

Particularly preferred is one with a resistance of 1014 Ω·cm or more. Specific examples include the following organic polymers.

Vinyl resins such as polyvinyl chloride, polyvinyl butyral, polyvinyl alcohol, polyvinylidene chloride, polyvinyl acetate, and polyvinyl formal; polystyrene,
Polystyrene resins such as styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer; polyethylene resins such as polyethylene, ethylene-vinyl acetate copolymer; polymethyl methacrylate, polymethyl methacrylate-styrene copolymer, etc. Acrylic resin; resin materials such as polyacetal, polyamide, cellulose, polycarbonate, phenoxy resin, polyester, fluororesin, polyurethane, phenol resin, urea resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin; natural rubber, impregnated resin, etc. Ngomu.

Butadiene rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber, chloroprene rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, nitrile rubber, acrylic rubber, urethane rubber, polysulfide rubber,
Rubber materials such as silicone rubber, fluororubber, silicone-modified ethylene-propylene rubber, etc.

On the other hand, as a conductive material used for the conductor part.

]012Ω・cm or less, preferably 10″Ω・cm or less. Specific examples include AQ, SUS
In addition to metals such as , Fc, and Nj, and ceramics, examples include organic polymers to which a conductivity imparting agent is added. In this case, the organic polymers include the same ones as exemplified as the dielectric material.

In addition, conductivity imparting agents include metal powders such as N1 and Cu; carbon blanks such as furnace black, lamp black, thermal black, acetylene black, and channel black; tin oxide, zinc oxide, molybdenum oxide, antimony oxide, and titanic acid. Conductive oxides such as potash; electroless plated materials such as titanium oxide and mica; inorganic fillers such as graphite, metal fibers, and carbon fibers; surfactants; and the like.

Note that an organic ion conductor in which metal ions are coordinated to a polymer matrix such as polyethylene oxide or polysiloxane can also be used.

The developer carrier of the present invention is characterized in that one or both of the dielectric part and the conductive part contains a charge control agent. In this case, the charge control agent used is the same as that used for controlling the polarity of toner and the like. Specifically, things that give a positive charge include electron-donating dyes such as nigrosine dyes, quaternary ammonium salts, basic dyes, triphenylmethane dyes, amino group-containing polymers, etc. As for things that give electrical charge,
Any conventionally known dyes such as chromium-containing monoazo dyes, chlorine-containing organic dyes, and metal salts of salicylic acid derivatives can be used, but they are not limited to these.

This charge control agent is usually added to the dielectric part, but it can also be added to the conductive part if the conductive part is made of a conductive polymer.

This allows for more precise charging control. That is, the charge control agent may be contained in either the dielectric part or the conductive part, but it is more preferable that the charge control agent be contained in both.

In order to more effectively control the charging of toner using the developer carrier of the present invention, it is preferable to use different charge control agents to be contained in the developer carrier depending on the polarity of the toner used. That is, when the toner to be used has positive polarity, it is preferable to add the above-mentioned positive charge control agent, and when the toner used has negative polarity, it is preferable to add the above-mentioned negative charge control agent.

By adding the control agent, the triboelectrification property of the toner increases, and it becomes possible to use dielectric or conductive materials that could not be used conventionally due to insufficient triboelectrification of the toner. Moreover, ideal toner charge amount and adhesion amount can be easily obtained.

These charge control agents may be dissolved and dispersed in a common solvent with the material used, or may be directly dispersed in the material. The developer carrier is produced by a conventional molding method such as spray dipping, injection molding, extrusion molding, or press molding. As a representative example of a specific method for manufacturing a developer carrier, the case of a V-groove type roller shown in FIG. 2 will be described.

(i) First, a metal roller whose surface is grooved is prepared. A method such as fleur-de-lis knurling is used to form the grid-like V-grooves. (2) The grooves have a pitch of 0.1 to 0.5 mm and are formed at an angle of about 45 degrees with respect to the longitudinal direction of the roller.

(ii) Next, (1) coat the grooved metal surface with a dielectric material in which a charge control agent has been dispersed in advance;

harden or dry. The coating thickness should be such that the grooves are completely filled.

(iii) Next, the surface of the roller is cut or polished so that the conductive surface and the dielectric surface are mixed in a small area,
Cut so that the area of the conductive part is 20 to 60%.

〔Example〕

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

Example 1 Charge control agent Nigrosine dye Charge control agent/dielectric part resin (solid content ratio): 0.1 ■ A grooved metal roller was spray coated with the above material, and then polished to form a conductive part of 502. A developer carrier (developing roller) was produced.

Example 2 A developing roller was produced in the same manner as in Example 1, except that a phenol resin (trade name: Pryophen TD-447; manufactured by Dainippon Ink and Chemicals, Inc.) was used as the dielectric resin.

Example 3 A developing roller was produced in the same manner as in Example 1, except that urethane resin (trade name C230U; manufactured by Hirono Chemical Co., Ltd.) was used as the dielectric resin.

Example 4 Polyamide resin (product name: C-8000) was used as the dielectric resin.
A developing roller was produced in the same manner as in Example 1, except that a developing roller (manufactured by DuPont Toray) was used.

Comparative Examples 1 to 4 Comparative developing rollers were produced in the same manner as in Examples 1 to 4, except that no charge control agent was used.

Example 5 A chromium-containing monoazo dye was used as a charge control agent, and an addition reaction silicone resin (trade name 5R24) was used as a dielectric material.
A developing roller was produced in the same manner as in Example 1, except that 07; manufactured by Toray Silicone Co., Ltd.) was used.

Example 6 Except for using a chromium-containing monoazo dye as a charge control agent,
A developing roller was produced in the same manner as in Example 1.

Comparative Example 5 In Example 5, except that no charge control agent was used,
A comparative developing roller was produced in the same manner as in Example 5.

Each developing roller of the tail plate was attached to the developing device shown in FIG. 1, and positively charged toner was loaded, and the amount of toner charge (blow-off method) and the amount of toner adhesion (tape transfer method) were measured. The results are shown in Table 1.

In the above-mentioned developing device, the toner thinning blade was made of urethane rubber, and the toner supply roller was equipped with a conductive urethane sponge ring.

Table 1 From Table 1, it can be seen that according to the present invention, dielectric materials (for example, polyamide resin,
It is now possible to use urethane resin, etc., and the amount of toner charge and toner adhesion can be controlled arbitrarily.

Next, the developing device is loaded with negatively charged toner,
The toner charge amount and toner adhesion amount were measured in the same manner as above. The results are shown in Table 2.

Table 2 From Table 2, it can be seen that according to the present invention, it is possible to increase the toner charge amount and toner adhesion amount, and to obtain stable toner charge amount and toner adhesion amount for various materials.

〔Effect of the invention〕

The developer carrier according to claim (1) is configured to contain a charge control agent in at least one of the dielectric portion and the conductive portion on the surface thereof. Image formation in which the developer is supported on the surface of the developer carrier by a large number of minute closed electric fields near the surface of the developer carrier by holding an electric charge, and the electrostatic latent image is visualized by the supported developer. When the developer carrier of the present invention is used in the method, a large amount of sufficiently charged non-magnetic one-component developer can be carried on the developer carrier and transported to the development area stably for a long period of time. , high-density, high-quality images can be stably obtained.

Further, the developer carrier according to claim (2) can further increase the amount of charge of the toner by containing a charge control agent having a chargeability depending on the polarity of the toner used.

[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 field due to a microfield is generated on the developer carrier of the present invention in the apparatus shown in FIG. Further, FIGS. 3(a) and 3(b) are schematic cross-sectional views showing an example of the structure of the surface of the developer carrier of the present invention. 10... Electrostatic latent image carrier, 20... Developer carrier, 3
0... Toner layer thickness regulating member, 40... Toner supply member, 50... Stirring blade, 60... Toner, 70... Toner tank, 80... Development area. Figure 1 Patent applicant Rico Co., Ltd.

Claims (2)

[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 dielectric part and a conductive part are mixed in a small area on the surface thereof, and either or both of the dielectric part and the conductive part are charged. A developer carrier characterized by containing a control agent. (2) When the toner has positive polarity, the positive charge control agent
In addition, when the toner has negative polarity, a negative charge control agent is used.
The developer carrier according to claim 1, wherein the developer carrier contains: