JP2959639B2 - Method for manufacturing developer carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention supplies a non-magnetic one-component developer externally supplemented with an auxiliary agent as necessary to a rotatable developer carrier,
Carrying and transporting the developer on the surface of the outer developer carrier,
In a developing region where the latent image carrier and the developer carrier are opposed to each other, the electrostatic latent image formed on the latent image carrier is visualized by the developer carried on the developer carrier. The present invention relates to a method for manufacturing a developer carrier used in an image forming method.

[Conventional technology]

An image forming apparatus such as an electronic copier, a printer or a facsimile that forms a latent image on a latent image carrier and visualizes the latent image with a developer to obtain a recorded image is a dry type using a powdery developer. Is widely used.

As such a powdery developer, a two-component developer having a toner and a carrier and a one-component developer without a carrier are known, and two-component development using the former two-component developer is known. In the method, although a relatively stable and good recorded image is obtained, deterioration of the carrier and fluctuation of the mixing ratio of the toner and the carrier are apt to occur, maintenance of the apparatus is complicated, and the structure of the entire apparatus is easily enlarged. Has disadvantages.

From such a viewpoint, a one-component developing method using a one-component developer which does not have the above-mentioned disadvantages has attracted attention. The one-component developer includes a toner composed of only a toner and a mixture of a toner and an auxiliary agent to which an auxiliary agent is added as necessary. As the toner, there are a magnetic toner in which magnetic powder is kneaded into each toner particle itself, and a non-magnetic toner containing no magnetic material.

Here, since the magnetic material is generally opaque, if a color image including full-color or multi-color is formed with magnetic toner, the developed visible image becomes unclear and a vivid color image cannot be obtained. Therefore, it is desirable to adopt a one-component developing method using a non-magnetic toner especially for color development.

By the way, in a developing device employing a one-component developing method, a one-component developer is carried on a developer carrier and transported. In a developing region where the developer carrier and the latent image carrier are opposed to each other, The electrostatic latent image formed on the latent image carrier is visualized with a developer, but in order to form a high quality visible image of a predetermined density, a large amount of sufficiently charged toner must be applied to the developing area. The latent image needs to be conveyed and visualized with the toner.

When the magnetic toner is used, the above-described requirement can be satisfied relatively easily because the one-component developer can be carried on the developer carrier by using the magnetic force of a magnet provided in the developer carrier. Is possible.

However, when a non-magnetic one-component developer is used,
Since this cannot be carried on the developer carrying member by magnetic force, it is difficult to satisfy the above requirements. Various countermeasures against this have been proposed in the past. For example, JP-A-61-42672 discloses a developer carrier (developing roller).
A layer of a dielectric (insulator) is formed on the surface of the substrate, and a developer supply member such as a sponge roller is pressed against the layer to frictionally charge the two with different polarities. A method has been proposed in which a non-magnetic toner charged to a polarity is electrostatically attached to a dielectric and such a one-component developer is transported to a development area. However, even with this method, the strength of the electric field formed in the vicinity of the dielectric surface cannot be sufficiently increased, so that it is difficult to carry a large amount of toner on the surface of the developing roller, and the developing roller can be transported to the developing area. Insufficient amounts of the agent make it difficult to form a high-density visible image.

A configuration in which a non-magnetic toner is applied between the developing roller and the developer supply member in a direction in which the non-magnetic toner is electrostatically transferred to the developing roller 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.

Examples of the toner supply member include a conductive foam of 10 ² to 10 ⁶ Ω · cm (JP-A-60-229057), an elastic body with a skin layer (JP-A-60-229060), and a fur brush. (Japanese Patent Application Laid-Open No. 61-42672) and the like, and as a developing roller, a metal body having an uneven surface (Japanese Patent Application Laid-Open No. 60-53976), an insulating coated roller body ( Japanese Unexamined Patent Publication No. Sho 55-46768 discloses a medium resistance coated roller (Japanese Unexamined Patent Publication No. 58-13278) and an electrode roller having an insulator and a conductive surface (Japanese Unexamined Patent Publication No. Sho 53-36245). .

In a developing apparatus using a non-magnetic one-component developer, a sponge roller is disclosed in JP-A-60-229057, an elastic roller is disclosed in JP-A-62-222960, and a developing roller is disclosed in JP-A-61-52663.
In the publication, a fur brush or the like is used to apply electric charge to the toner by frictional charging between the toner and the replenishing member, and further, by friction in contact with the developing roller, electrostatically attaches the toner to the developing roller. The latent image on the photosensitive member is developed by controlling the toner layer using a layer thickness regulating member such as a blade. As the material of the developing roller, various materials such as an insulating material, a medium-resistance material, and a laminated material are used.

According to the methods described in these references, toner is adhered to the developing roller by frictional charging between the toner replenishing member and the developing roller. And toner adhesion is insufficient. The following describes the optimal amount of adhesion and the amount of charge in the non-magnetic one-component developing system.

For black and white, the charge amount is important, and it is generally 10 to
20 μC / g. If the value is smaller than this value, the image quality such as background smear and sharpness is inferior. Regarding the coating weight, although the adhesion amount on the developing roller is 0.1 to 0.3 mg / cm ^2, the transfer paper is required 0.4~0.5mg / cm ^2, the speed of the developing roller of the photosensitive body speed 3 to 4 times, the amount of adhered toner is covered. However,
For the rotation of the developing roller 3 to 4 times, "from the rear end of the toner"
In other words, when the solid portion is developed, that is, the development that the density at the rear end of the image becomes high occurs. To prevent this development, the speed of the developing roller should be made closer to the speed of the photoconductor. That is, the number of rotations must be reduced by increasing the amount of adhesion on the developing roller.

On the other hand, in the color toner, the color characteristics are small in degree of coloring in comparison with black toner, and when you try to improve the "from toner rear", further more 0.8~1.2mg / cm ² compared to the black toner
Is required on the developing roller. Also, regarding the charge amount, in order to obtain a stable image, 5 to 20 μm
A value of C / g (preferably 10-15 μC / g) is desired.

As a method for solving these problems, the present inventors have previously described "a one-component developer composed of a non-magnetic toner externally supplemented with an auxiliary agent as needed on a rotatable developer carrier." The developer is carried on the surface of the carrier, and is conveyed. The electrostatic latent image formed on the latent image carrier is developed in a developing area where the latent image carrier and the developer carrier face each other. In a developing method of visualizing an image with the developer carried on a developer carrier, a plurality of minute particles are formed in the vicinity of the surface of the carrier by selectively holding electric charges on the surface of the developer carrier. An image forming method in which a closed electric field is formed, the charged toner is sucked by the closed electric field, the developer is adhered to and supported on the surface of the developer carrier, and the electrostatic latent image is visualized by the carried developer. Suggested.

According to such a method, a large number of minute closed electric fields (microfields) are formed in the vicinity of the surface of the developer carrying member, so that the electric field intensity can be significantly increased as compared with the related art.
It has many advantages such that a large amount of charged non-magnetic toner can be carried on a developer carrier and transported to a development area.

However, an industrially advantageous method for producing a developer carrier used in such a method has not yet been sufficiently studied, and a solution has been desired.

[Problems to be solved by the invention]

An object of the present invention is to form a plurality of microfields in the vicinity of the surface of the developer carrying member, and a method for developing an electrostatic latent image in a developing area after holding the toner on the carrier by the microfields. In the developing area, the surface of the developer carrier and the surface of the electrostatic latent image can be maintained and maintained at a constant distance between the surface of the developer carrier and the surface of the electrostatic latent image carrier. It is an object of the present invention to provide a simple and inexpensive method for producing a developer carrier used in a developing method which does not impair the developability such as uneven development density by bringing the surface of the latent image carrier into contact.

[Means for solving the problem]

That is, according to the present invention, a large number of dielectric micro-regions made of a conductive elastic member main body, each of which is made of a dielectric material provided independently and at intervals on at least the surface thereof, are provided on the shaft core. In the method for manufacturing a developer carrier used for electrostatic latent image development having an elastic surface layer, a shaft and a conductive elastomer composition are placed in a mold having minute irregularities on the inner wall, and the minute irregularities are formed on the surface. Forming a conductive elastic layer having a conductive elastic layer on a shaft core, removing the conductive elastic layer from the shaft core, embedding a dielectric material in the surface recesses, integrating the dielectric material with the surface elastic layer, and smoothing the surface. A method for manufacturing an agent carrier is provided, and on a shaft core, a conductive elastic member main body, at least on its surface, each of which is made of a dielectric material provided independently and at intervals. In a method of manufacturing a developer carrier used for electrostatic latent image development having an elastic surface layer provided with a large number of electro-microscopic regions, a large number of minute projections made of a dielectric material are attached to an inner wall of a mold. After that, the shaft core and the conductive elastomer composition are put therein, and the elastic surface layer is integrated on the shaft core, and the fine surface protrusion made of the dielectric material is embedded in the elastic surface layer. And subjecting the surface to a smoothing treatment as necessary.

By using the developer carrier obtained by the method of the present invention, a precise gap between a rigid latent image carrier such as a photoconductor provided with photoconductivity on a metal drum and the developer carrier is provided. There is no need for maintenance and the like, and the design tolerance can be widened.

First, an image forming method using the developer carrier manufactured by the method of the present invention will be described.

FIG. 1 shows an outline of a typical developing device useful for carrying out this image forming method, focusing on a developer carrying portion. First
In the figure, the toner 60 contained in the toner tank 70 is
Is forcibly brought to a toner supply member (such as a sponge roller or a fur brush) 40 by a stirring blade (toner supply auxiliary member) 50, and the toner 60 is supplied to the toner supply member 40. On the other hand, the developer carrier (developing roller: for example, 20φ) 20 having completed the development rotates in the direction of the arrow (for example, 100
pm), and reaches a 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, 67 rp).
m) Then, the developer carrier 20 and the toner 60 are charged, and the toner 60 adheres to the developer carrier 20. Further, the developer carrier 20 rotates, and the toner attached to the developer carrier 20 is stabilized in charge while being controlled in thickness by the toner layer thickness regulating member (elastic blade) 30, and reaches the developing region 80. In the developing region 80, the developer carrier 20 and the latent image carrier 10 are brought into rotational contact in the same direction on the surface thereof (the rotational speed of the latent image carrier: for example, 120 rpm). The latent image is developed. Here, as necessary, DC, AC, DC superimposed AC,
An optimum image can be controlled by applying a bias 90 such as a pulse.

In addition, when the amount of deformation of the surface elastic layer on the surface of the developer carrier in the development area is set to be equal to or less than 3/10 of the thickness of the elastic layer, deformation of the entire developer carrier is less likely to occur, and contact is prevented. This is preferable in order to suppress the generation of vibration due to.

Next, a method for producing the developer carrier of the present invention will be described.

A first method of the present invention for producing a developer carrier includes a step of placing a shaft core and a conductive elastomer composition in a mold having minute irregularities on an inner wall, and forming a conductive elastic layer having minute irregularities on a surface. This is a method in which a molding process is performed on the upper surface, the substrate is taken out, a dielectric material is buried in the surface recesses, integrated with the surface elastic layer, and then the surface is smoothed.

As a method for providing minute irregularities on the inner wall of the mold, a conventionally known method such as a sand blast method or a knurling method is employed.

Further, as the conductive elastomer composition, one obtained by adding a conductivity-imparting agent to an elastomer (rubber material) is used.

Examples of the elastomer include the following.

Diene rubbers such as styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile-butadiene rubber (NBR), nitrile-isoprene rubber (NIR), chloroprene rubber (CR); butyl rubber (IIR) ), Olefin rubbers such as ethylene-propylene rubber (EPM, EPDM) and chlorosulfonated polyethylene (CSM); ether rubbers such as epichlorohydrin rubber (CHR, CHC); other silicone rubber, fluorine rubber, acrylic rubber, urethane rubber And elastomer materials such as thermoplastic elastomers such as styrene, olefin, polyvinyl chloride, urethane, polyester, polyamide, fluorine and chlorinated polyethylene.

Further, as the conductivity-imparting agent, metal powders such as Ni and Cu;
Carbon blacks such as furnace black, lamp black, thermal black, acetylene black and channel black; conductive oxides such as tin oxide, zinc oxide, molybdenum oxide, antimony oxide and potassium titanate; plating on titanium oxide and mica Electroless plated material; examples include inorganic fillers such as graphite, metal fibers, and carbon fibers, and surfactants.

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

As the shaft core, a conductive substrate, for example, a metal material such as Al, Fe, and SUS is used.

Further, as the dielectric material embedded in the surface of the elastic surface layer, a dielectric material of 10 ¹³ Ω · cm or more, preferably 10 ¹⁴ Ω · cm or more is used.

The average particle size is preferably 30 μm or more, and more preferably 50 μm or more. If it is less than 30 μm, it is difficult to form a microfield, and stable toner adhesion and charging cannot be obtained. It should be noted that, regardless of whether it is a fixed or irregular shape, the use of an irregular shape is superior in that the dielectric material does not separate from the conductive elastomer during the surface smoothing process.

Specific examples of these materials include alumina, beryllia, magnesia, silicon nitride, boron nitride, mullite,
Inorganic particles such as steatite, forsterite, zircon, cordierite, epoxy resin, fluorine resin,
Organic particles such as a silicone resin, an acrylic resin, a polyamide resin, a polystyrene resin, a phenol resin, a melamine resin, and a polyethylene resin are exemplified. In the present invention, it is preferable to use an elastomer as the dielectric material.

As the elastomer in this case, the same material as the elastomer used for the conductive elastomer is used.

To produce dielectric elastomer particles, after freezing the elastomer with dry ice or the like, pulverizing and pulverizing, a method of pulverizing and pulverizing with a grinder, forming an aqueous emulsion using a surfactant, etc.,
A known method such as a curing method is employed.

In addition, as the elastomer used for the conductive elastomer composition and the dielectric material, silicone rubber is particularly preferable from the viewpoint of low hardness, environmental resistance, mold release property, and the like.

The second method of the present invention for producing a developer carrier includes a method in which a large number of minute projections made of a dielectric material are attached to the inner wall of a mold, and then a shaft core and a conductive elastomer composition are added. A method in which an elastic surface layer is integrated thereon, and a developer carrier in which fine projections made of the dielectric material are embedded in the elastic surface layer is taken out, and if necessary, the surface is smoothed. .

In this case, as the conductive elastomer composition, the shaft core, and the dielectric material, the same materials as those used in the first method can be used.

In the second method, in order to attach a large number of minute projections made of a dielectric material to the inner wall of the mold, an adhesive is first applied to the inner wall surface, and a dielectric material (insulating material) is formed thereon. It can be obtained by spraying powder. Another method is to apply a water-repellent or oil-repellent material such as a fluorine-based surfactant to the inner wall and then spray a solution of an insulating material such as a resin or an elastomer or an emulsion liquid to spray the liquid of the spray liquid on the inner wall surface. A method of forming a droplet and then solidifying the droplet is exemplified.

Further, as the smoothing method, conventionally known cutting or polishing can be used as it is.

As the mold used in the first and second methods,
The warp type is the most convenient and preferable, but it may be a drawing type. In this case, for example, after heating and curing the liquid elastomer, the cooled molded product is shrunk. By doing so, it can be easily pulled out.

Further, the area of the surface dielectric portion of the developer carrier used in the present invention is preferably in the range of 50 to 80%, and the amount of the dielectric material added is appropriately adjusted so as to be within this range after the production of the carrier.

In the present invention, when the developer carrier and the latent image carrier are developed while rotating in the same direction and at substantially the same speed as shown in FIG. It is preferable that the strain (JIS K 6301) is 25% or less. As a result, a sufficient amount of toner can be carried and conveyed on the developer carrier, and the occurrence of vibration due to the contact rotation between the two carriers can be suppressed, so that there is no development density unevenness. It has the advantage that.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples. Parts represent parts by weight.

Example 1 A conductive silicone rubber (trade name: DY32-700u; manufactured by Toray Silicone Co., Ltd.) was wrapped around the surface of a SUS metal roller to which a conductive primer (trade name: DY39-011; manufactured by Toray Silicone Co., Ltd.) was previously applied. After putting it into a mold press mold with square groove knurling of 0.4mm pitch and 0.5mm depth on the inner wall, primary vulcanization (170 ℃ / 10min, 120kgf
/ cm ² ) and subjected to secondary vulcanization (200 ° C. for 4 hours) to mold.
Next, after applying X and Y primers (manufactured by Toray Silicone Co., Ltd.) on the surface of the mold removed from the molding machine, a soft silicone resin (product name: SR2407: manufactured by Toray Silicone Co., Ltd.)
Was applied by spraying to fill the surface recesses with a soft silicone resin. After curing at 150 ° C. for 1 hour, the surface was polished to prepare a developer carrying member.

Example 2 50% of liquid silicone rubber (trade name: DX35-203: manufactured by Toray Silicone Co., Ltd.) is applied to the entire inner wall of the warri-type press-formed metal.
After applying the toluene solution, silicone rubber particles (particles having an average particle diameter of about 200 μ obtained by freeze-pulverizing and classifying SE1185u manufactured by Toray Silicone Co., Ltd.) were sprayed and dried. Next, a metal roller around which conductive silicone rubber was wound as in Example 1 was set in a molding machine, vulcanization was performed under the same conditions as in Example 1, molding was performed, and then surface polishing was performed to obtain a developer carrier. Was prepared.

〔The invention's effect〕

According to the manufacturing method of claims (1) and (2), a developer carrier used for developing an electrostatic latent image having a conductive elastic layer having independent fine dielectric portions on the surface thereof on the axis is simple. In addition, it can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view centering on a developer carrying portion showing an example of a developing device in which a microfield electric field is formed on a developer carrying member useful for carrying out the present invention. 10 electrostatic latent image carrier, 20 developer carrier, 20 toner layer thickness regulating member, 40 toner supply member, 50 stirring blade, 60 toner, 70 toner tank , 80: developing area, 90: bias.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuichi Ueno 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (72) Inventor Naoki Iwata 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 15/08-15/09 F16C 13/00

Claims (2)

(57) [Claims] 1. An electroconductive elastic member main body on a shaft core,
Manufacture of a developer carrier used for electrostatic latent image development, having an elastic surface layer provided with a large number of dielectric minute regions made of a dielectric material provided independently and at intervals on at least the surfaces thereof In the method, the shaft core and the conductive elastomer composition are put into a mold having minute irregularities on the inner wall, and a conductive elastic layer having minute irregularities on the surface is subjected to molding on the shaft core, and then taken out. A method for producing a developer carrying member, comprising: embedding a dielectric material in the surface recesses, integrating the dielectric material with the surface elastic layer, and then smoothing the surface. 2. An electroconductive elastic member main body on a shaft core,
Manufacture of a developer carrier used for electrostatic latent image development, having an elastic surface layer provided with a large number of dielectric minute regions made of a dielectric material provided independently and at intervals on at least the surfaces thereof In the method, after allowing a large number of minute projections made of a dielectric material to adhere to the inner wall of the mold, put the shaft core and the conductive elastomer composition,
The developer carrier having the elastic surface layer integrated on the shaft core and having the fine protrusions made of the dielectric material embedded in the elastic surface layer is taken out and, if necessary, the surface is smoothed. A method for producing a developer carrying member, comprising: