JPH0450879A - developer carrier - Google Patents

Abstract

PURPOSE:To sufficiently secure toner adhesion quantity and toner electrification quantity, and also, to obtain the developer carrier at a low cost by forming a conductive material containing insulating particles as a surface layer. CONSTITUTION:A surface layer consisting of a conductive material in which insulating particles are dispersed is provided on a conductive base body, charge is held selectively on the surface of a developer carrying body, and many minute closed electric fields are formed in the vicinity of the surface of the developer carryier. In such a state, by the minute closed electric fields, a developer is carried on the surface of the developer carrying body, and an electrostatic latent image is converted to a visible image by the carried developer. In such a way, the toner adhesion quantity and the toner electrification quantity are secured stably extending over a long period, and also, the carrying body can be obtained at a low cost since it can be manufactured simply.

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. 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 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). 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.

Note that the toner supply member has a resistance of 102 to 10'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, a metal body with an uneven surface (Japanese Patent Application Laid-Open No. 1986-
No. 53976), integrated insulation coated roller (Japanese Unexamined Patent Publication No. 55
-46768 Publication) Medium and low antibody coated roller (JP-A-Sho sg
13278) 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 -10~ for boat fishing.
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 to 0.3 mg/am2, but 0.4 mg/am2 on the transfer paper
~0.5 [l1g/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, 3-4
The problem with rotating the developing roller twice as much is that a phenomenon of "toner from the trailing edge" occurs, that is, when a solid area is developed, the density at the trailing edge of the image becomes higher. 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, in the case of color toner, its color characteristic is that it sinks into the black toner and the degree of coloration is small, and if you try to improve the "from the rear end of the toner", it will be 0.8 to 1.2 m longer than the black toner.
The amount of adhesion on the developing roller of "g/cm" 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 for eliminating these intermittent points, the present inventors have
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 conventional methods, 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.

[Problems to be Solved by the Invention] However, when manufacturing the developer carrier used in the image forming method in which a large number of microfields are formed near the surface of the developer carrier, a metal roller is used. It requires many steps such as microfabrication, resulting in high costs.

Therefore, an object of the present invention is to provide a developer carrier that can ensure sufficient toner adhesion and toner charge in the image forming method, and that can be produced by a simple manufacturing method and at low cost. There is a particular thing.

[Means to solve the problem]

As a result of intensive study, the inventors found that! The present inventors have discovered that a developer carrier having a surface layer formed of a conductive material containing fringe particles is suitable for the above purpose, and has 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. There is provided a developer carrier characterized in that a surface layer formed by dispersing insulating particles in a conductive material is formed on a conductive substrate.

In the image forming method using the developer carrier of the present invention, since a large number of minute electric fields are formed near the surface of the developer carrier, the electric field strength can be significantly increased compared to conventional methods. Since this developer carrier has a structure in which a surface layer made of a conductive material in which insulating particles are dispersed is provided on a conductive substrate, a stable toner adhesion amount and toner charge amount can be obtained, and the carrier Since it can be easily produced, it is possible to reduce costs.

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.
0, the toner 60 is forcibly brought to the toner supply member 4
0. 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, the developer carrier 2
0 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, 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 developer carrier of the present invention will be explained.

As described above, the developer carrier of the present invention has a structure in which a surface layer made of a conductive material in which insulating particles are dispersed is formed on a conductive substrate. , 10"Ω・cm or less, preferably 10@Ω・
Those having Cl11 or less can be used. Specifically, examples include organic polymers to which a conductivity imparting agent is added. In this case, the organic polymers include resin materials (plastomers) and rubber materials (elastomers), and specific examples thereof include the following.

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; other polyacetal, polyamide,
Plastomer materials such as cellulose, polycarbonate, phenoxy resin, polyester, fluororesin, polyurethane, phenolic resin, urea resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin.

Styrene-butadiene rubber (SBR), butadiene rubber (BR), imprene rubber (IR), nitrile-butadiene rubber (NBR), nitrile-isoprene rubber (NI
R), diene rubber such as chloroprene rubber (CR);
Butyl rubber (IIR), ethylene-propylene rubber (E
PM, EPDM), chlorosulfonated polyethylene (
Olefin rubbers such as C3M); ether rubbers such as epichlorohydrin rubber (CHRlCHC); other silicone rubbers, fluororubbers, acrylic rubbers, urethane rubbers, as well as styrene rubbers, olefin rubbers, polyvinyl chloride rubbers, urethane rubbers, and polyester rubbers. , elastomer materials such as thermoplastic elastomers such as polyamide-based, fluorine-based, and chlorinated polyethylene-based.

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

Furthermore, organic ion conductors in which metal ions are coordinated to a polymer matrix such as polyethylene oxide or polysiloxane can also be used.

Note that when an elastomer is used among the organic polymers as the conductive material, the surface layer of the developer carrier has elasticity, making it easier to contact the rigid drum-shaped photoreceptor. The use of electrically conductive elastomers is particularly preferred since contact development is greatly facilitated.

On the other hand, as an insulating particle material, 1013Ω・Cl11
Above, preferably 1014 Ω·cm or more is used. Further, the average particle diameter is preferably 5 tones or more, preferably 10 tones or more. If it is less than 5, it is difficult to form a microfield and stable toner adhesion and charging cannot be obtained. In addition, it does not matter whether it is a fixed form or an amorphous form.

These specific materials include alumina, beryllia,
Inorganic particles such as magnesia, silicon nitride, boron nitride, mullite, steatite, forsterite, zircon, cordierite, epoxy resin, fluororesin, silicone resin, acrylic resin, polyamide resin, polystyrene resin, phenolic resin, Examples include organic particles such as melamine resin and polyethylene resin.

Note that when the conductive elastomer is used as the conductive material, it is preferable to use the elastomer as the insulating particles in order to further promote low hardness. As the elastomer in this case, the same material as exemplified as the elastomer used for the conductive elastomer is used. Insulating elastomer particles can be produced by freezing the elastomer with dry ice or the like and then pulverizing it into powder, by crushing it with a grinder and pulverizing it, or by forming an aqueous emulsion using a surfactant, etc. A known method such as a curing method is employed.

In addition, elastomers used for conductive materials and insulating particles are selected from the viewpoints of low hardness, environmental resistance, mold release properties, etc.
Particularly preferred is silicone rubber.

The amount of insulating particles added to the conductive material is appropriately selected in the range of 10 to 200 parts by weight based on 100 parts by weight of the conductive material. The area of the surface insulation part of the developer carrier is 2
A range of 0 to 60% is preferable, and the amount of insulating particles added is adjusted as appropriate so that it falls within this range after producing the carrier.

Next, a method for manufacturing the developer carrier of the present invention will be explained. FIG. 2 shows a typical structural example (an enlarged partial sectional view of the surface) of the surface of the developer carrier of the present invention. The developer carrier having the surface shown in FIG. 2 is produced by adding the insulating particles to the conductive material using a conventional dispersion method such as ball milling or kneading, and then injection molding the mixed material. It is manufactured by molding on a conductive substrate, typically a metal roller made of SUS, iron, AQ, etc., using methods such as extrusion molding, spray coating, or dipping, and then polishing the surface to make it smooth. This is an example.

Note that in order to improve the adhesion between the conductive material and the conductive substrate, it is also possible to use a primer, and in this case, the primer is preferably conductive.

〔Example〕

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

Example 1 Conductive paint 100
Part: The coating liquid with the above formulation was applied to a SUS metal roller by spray coating, and after drying at 80°C for 1 hour,
Polished developer carrier (developing roller) with a film thickness of 100 threshold
was created.

Example 2 10 parts of Ketchien Black EC (manufactured by Akzoshimie) Ball milling was performed for 72 hours according to the above recipe to produce a carbon black masterbatch.

Masterbatch 100 parts Toluene 100 parts A developing roller was produced in the same manner as in Example 1 using the coating liquid having the above formulation.

Example 3 Methylvinylsiloxane raw gum 100 parts Fluorosiloxane raw gum 100 parts After kneading the above mixture with two rolls, a crosslinking agent (2,4-dimethyl-2,4-di-tert-butyl 1.5 parts of peroxyhexane (trade name: RC-4, manufactured by Toray Silicone Co., Ltd.) was added to prepare a molding compound.

A molding compound with the above formulation was applied onto a SUS metal roller coated with a conductive primer (trade name DY39-011: manufactured by Toray Silicone Co., Ltd.) in advance, and then vulcanized at 170°C/10 minutes, 120 kgf/cI. ! +2, Secondary vulcanization: A surface layer was formed by press molding at 200°C for 4 hours, and then polished to produce a developing roller.

Example 4 Instead of wA edged silicone particles used in Example 3,
Insulating silicone rubber particles (trade name: TOREFIL E-8)
A developing roller was produced in the same manner as in Example 3, except that a developing roller (No. 50; manufactured by Toray Silicone Co., Ltd.) was used.

(2) The developing rollers obtained in Examples 1 and 2 were installed in the developing device shown in FIG. 1, and the amount of toner charge and toner adhesion was measured. The results are shown in Table 1.

In the above developing device, the toner thinning blade is made of urethane rubber, the toner supply roller is made of conductive urethane sponge, and the toner is positively charged toner.
The photoreceptor was loaded with a belt-like photoreceptor comprising an organic charge generation layer and an organic charge transfer layer sequentially provided on a support.

From the results shown in Table 1, it can be seen that the developing rollers manufactured in Examples 1 and 2 can obtain stable toner adhesion amounts and toner charge amounts.

Subsequently, for the developing rollers obtained in Examples 3 and 4, the above-mentioned developing device was used, and the drum OP was used only as a photoreceptor.
C was attached, and the toner charge amount and toner adhesion amount were measured in the same manner. The results are shown in Table 2.

Table 2 From the results shown in Table 2, the developing rollers manufactured in Examples 3 and 4 were able to obtain stable toner adhesion amounts and toner charge amounts, and were also compatible with contact developing devices using drum photoreceptors. It turns out that it is easy to use.

〔Effect of the invention〕

The developer carrier of claim (1) has a structure in which a surface layer made of a conductive material in which insulating particles are dispersed is provided on a conductive substrate. A non-magnetic one-component system consisting of toner with an externally added auxiliary agent is formed on the developer carrier by holding an electric charge to form a large number of minute closed electric fields near the surface of the developer carrier. An image forming method according to claim (1), wherein a developer is supplied, the developer is carried on the surface of a developer carrier by the minute closed electric field, and an electrostatic latent image is visualized by the carried developer. When a developer carrier is used, not only a stable toner adhesion amount and toner charge amount are ensured over a long period of time, but also the carrier can be easily manufactured, making it possible to reduce costs.

Furthermore, since the developer carrier of claim (2) is configured such that the conductive material is made of a conductive elastomer, it has the effect that it can be brought into contact with the rigid drum-shaped photoreceptor very easily. join.

[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 partial sectional view 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. Patent owner 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. 1. A developer carrier used in an image forming method, characterized in that a surface layer formed by dispersing insulating particles in a conductive material is formed on a conductive substrate. carrier. (2) The developer carrier according to claim 1, wherein the conductive material is a conductive elastomer.