JPH0427980A - Developer carrying member - Google Patents

Abstract

PURPOSE:To prevent charges from remaining on a surface by coating the surface of a smooth roller with a conductive adhesive layer, then adhering electrode particles onto this layer, coating the surface with dielectrics and further polishing the surface after drying to provide the microelectrode surface and incorporating a surfactant into the conductive adhesive layer. CONSTITUTION:This developer carrying member has the microelectrode surface obtd. by coating the surface of the smooth roller of the member with the conductive adhesive layer and adhering the electrode particles thereon, then coating the surface with the dielectrics and further polishing the surface after drying. In addition, the surfactant is incorporated into the conductive adhesive layer. The electric field intensity of the many microclosed electric field formed near the surface of the developer carrying member is, therefore, greatly increased. Since the surfactant is incorporated into the conductive adhesive layer existing between the electrode particles and the metallic roller, the characteristic to implant the charges from the metallic roller to the induced part is excellent and eventually, the charges remaining on the surface are formed with the electric fields in the implanted charge direction; in addition, the charge quantity in the dielectrics is offset. The remaining of the charges on the surface is prevented in this way.

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, if a color image including full color or multicolor is formed using magnetic toner, the developed visible image will be unclear and a vivid color image cannot be obtained. Particularly 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 attach a sufficient amount of toner to the developing roller.

Note that the toner supply member has a resistance of 10" to 10'Ω.
cm conductive foam (Japanese Patent Application Laid-Open No. 60-229057), an elastic body with a skin layer (Japanese Patent Application Laid-Open No. 60-229060), a fur brush (Japanese Patent Application Laid-open No. 61-42672), etc. has been proposed, and as a developing roller, a metal body with an uneven surface (Japanese Patent Laid-Open No. 60-5
No. 3976), integrated insulation coated roller (Japanese Unexamined Patent Application Publication No. 1987-
46768) Medium and low antibody coated roller (Japanese Patent Application Laid-open No. 1983-
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-62-229060 discloses an elastic roller.

JP-A No. 61-52663 discloses that a fur brush or the like is used to charge the toner by frictional charging between the toner and a replenishing member, and further electrostatically transfers the toner to the developing roller by the friction in contact with the developing roller. The latent image on the photoreceptor is developed by controlling the toner layer using a layer thickness regulating member such as a blade. 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. <<, resulting 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 to 0.3 mg/c2, but 0.4 mg/c on the transfer paper.
~0.511 g/cm" is required, and the amount of toner adhesion is covered by increasing the speed of the developing roller to 3-4 times the speed of the photoconductor. The rotation of the toner has the problem of causing a phenomenon called "toner from the rear edge", that is, when a solid area is developed, the density at the rear edge of the image becomes higher.To prevent this phenomenon, The speed of the developing roller must be brought close to the speed of the photoreceptor. In other words, the amount of toner deposited on the developing roller must be increased and the number of rotations must be decreased.

On the other hand, with color toner, the degree of coloring is smaller than that of black toner, and when trying to improve the "from the rear end of the toner", the color characteristic is 0.8 to 1.2 m, which is even more than that of 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 5-20 μC/g (preferably 10-15 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 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 closed 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, many small closed electric fields (microfields) are formed near the surface of the developer carrier, so the electric 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.

[Problems to be Solved by the Invention] However, in the image forming method in which a large number of microfields are formed near the surface of the developer carrier as described above, the developer carrier has an insulating dielectric material on its surface. To have
If the electrical charge generated by frictional charging with other parts tends to remain on the surface, and if the electrical charge remains even after the static electricity removal process,
There is a problem in that it affects the next process.

For example, if the charged charge of the toner remains, a negative afterimage will occur, and if the charged charge of the toner supply member or toner layer thickness regulating member remains, it will be detected as a residual potential, which may also have an adverse effect on the formation of microfields. become.

In order to solve this problem, it is possible to reduce the electrical resistance of the dielectric material and promote the leakage of residual charges.
If such a method is adopted, it becomes difficult to form a microfield, and the desired amount of toner adhesion and amount of charge cannot be obtained.

Therefore, an object of the present invention is to provide a developer carrier in which no charge remains on the surface of the developer carrier in the image forming method described above, without impairing the ability to form microfields on the surface of the developer carrier.

[Means to solve the problem]

As a result of extensive studies, the present inventors found that a developer carrier using a conductive adhesive containing a surfactant is suitable for the above purpose. The present invention has now been completed.

That is, according to the present invention, l! By selectively retaining a charge on the surface of the image side supporter, a large number of minute closed electric fields are formed near the surface of the developer supporter, and an auxiliary agent is applied on the developer supporter as necessary. A non-magnetic one-component developer made of toner externally added is supplied, the developer is carried on the surface of the developer carrier by the minute closed electric field, and the electrostatic latent image is visualized by the carried developer. Two developer carriers are used in the image forming method, in which a conductive gripping agent layer is coated on a smooth roller, an electrode shield is adhered thereon, a dielectric material is then coated, and after drying, polishing is performed. There is provided a developer carrier having a microelectrode surface obtained by the above method, and further characterized in that the conductive adhesive layer contains a surfactant.

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.
In addition to being able to significantly increase the electric field strength compared to conventional methods, the use of a surfactant-containing conductive adhesive layer that makes up the developer carrier maintains the insulation properties of the dielectric material. In other words, the ability to form microfields on the surface of the developer carrier is maintained, and there is no residual charge.As a result, a large amount of sufficiently charged non-magnetic toner is carried on the developer carrier and the developing area is maintained. It can be conveyed in a long time and has low afterimage property.

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.
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
On the other hand, the developer carrier (developing roller) 20 of the present invention, which has completed development, rotates in the direction of the arrow (for example, 400 rpm) I, 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, 300 rpm) L/, charges the developer carrier 20 and the toner 60, and charges the developer carrier 20.
A toner 60 is applied thereon.

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
0~500. The small areas of size 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 6 parts.

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 40 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 micro field (closed 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. . Furthermore, since the adhered toner forms a closed 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, in the developer carrier of the present invention, a mechanism will be described in which the residual charge disappears to such an extent that it does not affect the primary process while maintaining insulation.

A counter charge of the charge remaining on the surface of the developer carrier as the opposite charge of the frictional charging member with the toner and other members is induced in the conductive part directly below the dielectric part of the grounded developer carrier [see;
Figure 3(a)]. In the developer carrier of the present invention, since a surfactant is mixed in the conductive adhesive layer between the electrode particles and the metal roller, it has excellent charge injection characteristics from the metal roller to the dielectric part. Therefore, the induced charge is injected into the dielectric part, and as a result, the charge remaining on the surface forms an electric field in the direction of the injected charge, and the amount of charge inside the dielectric is canceled out [see Figure 3 (b)] ], it becomes difficult for electric force to act on the outside of the developer carrier.

The developer carrier of the present invention is characterized in that the conductive adhesive layer contained therein contains a surfactant, and in this case, the surfactant includes nonionic, cationic,
Both anionic and amphoteric compounds can be used. Specifically, nonionic compounds include ester compounds such as fatty acids, ether ester compounds, ether compound diamide condensates, and cationic compounds include aliphatic amine salts and their quaternary ammonium salts. salts, aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts, and the like.

In addition, anionic salts include alkyl carboxylates, N-acyl amino acid salts, alkyl ether carboxylates, acylated peptides, alkyl sulfonates, alkylbenzene and alkylnaphthalene sulfonates, sulfosuccinates, and α-olefins. Sulfonates, N-acyl sulfonates, alkyl sulfates, alkyl ether sulfates, alkyl allyl ether sulfates, alkyl amide sulfates, alkyl phosphates, alkyl ether phosphates, alkyl allyl ether phosphates, etc. mentioned,
Examples of amphoteric compounds include carboxybetaine, sulfobetaine, and aminocarboxylate salts. Among these, ionic ones are preferred in terms of their effects.

In addition, it is particularly preferable to use a fluorine-based surfactant that has excellent environmental resistance. Specific examples thereof include nonionic surfactants such as perfluoroalkyl group-containing lipophilic group-containing oligomers, perfluoroalkyl group-containing hydrophilic Examples include group-containing oligomers, perfluoroalkylethylene oxide adducts, and the like. In addition, cationic ones include perfluoroalkyl-containing quaternary ammonium salts, and anionic ones include perfluoroalkyl-containing sulfonic acids, monovalent metal salts of carboxylic acids, phosphate esters, and amphoteric ones. Examples include betaine containing perfluoroalkyl.

These can be appropriately selected from the viewpoint of compatibility with the materials used. It is also possible to use a mixture of various surfactants. The amount of the surfactant mixed is 0.00 parts by weight based on 100 parts by weight of the solid content of the resin material constituting the adhesive layer.
1 to 50 parts by weight is preferred.

More preferably, it is 0.5 to 20 parts by weight. If the amount is less than 0.1 part by weight, the effect will not be sufficient and an afterimage will occur.

On the other hand, if it exceeds 50 parts by weight, deterioration in environmental resistance and film-forming properties will occur.

The conductive adhesive used in the present invention includes epoxy resin,
A resin having adhesive properties such as polyimide resin, phenol resin, or polyester resin mixed with a conductivity imparting agent such as a conductive filler is used. In this case, the conductive filler includes, for example, Ag, Mu, Cu, Ni.
, Ag-plated Cu, Ag-plated glass, carbon black, etc.

In addition, the material used for the electrode particles has a volume resistance of 101
It is possible to use particles of 2 Ω·C or less, preferably 10” Ω·cl or less, and metal sphere particles (20 to 100 M) such as Cu or AQ are used.

In the present invention, these electrode particles are melted and kneaded,
After cooling this composition, it is pulverized and the pulverized product is classified to obtain particles having a target particle size range.

In the present invention, the material used as the dielectric is as follows.

Any insulating material can be used, but organic polymers are usually used. In this case, specific examples of organic polymers include the following.

Vinyl resins such as polyvinyl chloride, polyvinyl butyral, polyvinyl alcohol, polyvinylidene chloride, polyvinyl acetate, polyvinyl formal; polystyrene,
Polystyrene resins such as styrene-acrylonitrile copolymer and acrylonitrile-butadiene-styrene copolymer; polyethylene resins such as polyethylene and 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, etc.

For producing the developer carrier of the present invention, for example.

(i) First, a conductive adhesive containing a surfactant (resin such as epoxy, polyimide, phenol, or polyester with a conductive filler such as Ag, Au, Cu, Ni, etc.) is applied to the surface of the metal roller. Ag-metsted Cu
After applying 1g of plated glass, carbon black, etc.), the aforementioned electrode particles were embedded, and (ii
) Next, the dielectric material is coated by a method such as spraying or dipping, and the dielectric material is coated at a predetermined curing or drying temperature.
A dielectric part is formed over time, and then 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%. This method is adopted.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Cu particles (60/s) 1 mm diameter Fluororesin (trade name: Lumiflon LF200; manufactured by Asahi Glass Co., Ltd.) A developer carrier (developing roller) was produced using the above-mentioned ingredients in the following manner. .

(i) After applying the conductive adhesive on the SO5 roller, the electrode particles are embedded thereon.

(ii) Next, the dielectric material was spray coated on the surface of the embedded roller and cured at 100° C. for 1 hour. The coating thickness was such that the electrode particles were completely buried.

(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 Example 2 except that an anionic fluorosurfactant (C7F1□C00Na) was used instead of the cationic fluorosurfactant in Example 1 as the surfactant in the conductive adhesive layer. A developing roller was produced in the same manner as in Example 1.

Example 3 As a surfactant in the conductive adhesive layer, an amphoteric fluorine-based surfactant (CIF, tso, NH(C,
A developing roller was produced in the same manner as in Example 1 except that Hs')N.(CH,), C, H, and COO were used.

Example 4 As a surfactant in the conductive adhesive layer, a nonionic fluorine-based surfactant [C, F,, -H pseudo-CH24-] was used instead of the cationic fluorine-based surfactant in Example 1. A developing roller was produced in the same manner as in Example 1 except that .

Comparative Example A developing roller was produced in the same manner as in Example 1, except that the surfactant in the conductive adhesive layer was not used.

〔evaluation〕

Each developing roller was installed in the developing device shown in FIG. 1, and the amount of toner adhesion and the amount of toner charge on the roller were measured after one and ten rotations of the developing roller. 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.

Each developing roller was installed in the apparatus shown in FIG. 1, and an OPC was installed as a photoreceptor, and the afterimage was evaluated based on the pattern image. That is, after solid black development, halftone dots are developed, and the image density (IDL) of the halftone dot corresponding to the position of the black solid and the halftone image density (IDH) of the halftone dot immediately beside it, other than the area corresponding to the black solid.
The ratio (IDL/IDH) was measured using a Macbeth densitometer. The results are shown in Table 1.

From the results in Table 1, it can be seen that by using the developing roller of the present invention, a sufficient amount of toner adhesion and toner charge amount can be obtained, and the afterimage property is also low.

〔Effect of the invention〕

The developer carrier of the present invention has a structure in which a conductive part and a dielectric part coexist in a small area on the surface, and the conductive adhesive layer contains a surfactant. By selectively retaining charges on the surface, a large number of minute closed electric fields are formed near the surface of the developer carrier, and the toner to which an auxiliary agent is externally added as necessary is placed on the developer carrier. An image forming method comprising: supplying a non-magnetic one-component developer, causing the developer to be carried on the surface of a developer carrier by the minute closed electric field, and visualizing an electrostatic latent image by the carried developer; By using the developer carrier of the present invention, a large amount of sufficiently charged non-magnetic one-component developer can be carried on the developer carrier and transported to the development area, and the residual charge due to triboelectric charging can be reduced. effectively disappear. As a result, high-density, high-quality images can be stably obtained over a long period of time.

[Brief explanation of drawings]

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. Further, FIGS. 3(a) and 3(b) are schematic cross-sectional views for explaining the mechanism by which residual charges are eliminated while maintaining insulation in 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. Patent applicant Rico Co., Ltd. - Representative patent attorney Toshiaki Ikeura (and one other person) No. 1 Kamezu Yoto

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 conductive adhesive layer is coated on a smooth roller, electrode particles are adhered thereon, and then a dielectric material is coated, and after drying, polishing is performed. 1. A developer carrier having a microelectrode surface obtained by the above method, and further characterized in that the conductive adhesive layer contains a surfactant.