JPH04296767A - Image forming method - Google Patents

Abstract

PURPOSE:To provide the formation of the image which can laminate toner stably and uniformly in two layers on a developer carrier and suppresses its filming as to a development system which produces many fine closed electric fields nearby the surface of the developer carrier. CONSTITUTION:The toner which consists of at least binding resin and a coloring agent and contains a metal containing azo pigment electrostatic charging control agent is used. Many fine closed electric fields are produced nearby the surface of the carrier by holding charges selectively on the surface of the developer carrier and a single-component developer consisting of the toner is supplied onto the carrier; and the developer is carried on the surface of the carrier with the fine electric fields and the electrostatic latent image is visualized with the carried developer. This image forming method uses the developer to obtain an image of high quality with high density for a long period.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention supplies a one-component developer to which an auxiliary agent is externally added as necessary to a rotationally driven developer carrier, and applies the developed material to the surface of the developer carrier. The electrostatic latent image formed on the latent image carrier is conveyed while supporting the developer, and the electrostatic latent image formed on the latent image carrier is transferred to the developing area where the latent image carrier and the developer carrier face each other. The present invention relates to an image forming method in which images are visualized using a developer.

0002

2. Description of the Related Art In image forming apparatuses such as electronic copying machines, printers, and facsimile machines, an electrostatic latent image is formed on a latent image carrier and visualized with a developer to obtain a recorded image.
Dry type developing devices that use powdered developer are widely used.

[0003] As such powder-like developers, two-component developers containing toner and a carrier and one-component developers that do not contain a carrier are known. Although the two-component development method can provide relatively stable and good recorded images, it is prone to carrier deterioration and fluctuations in the toner-to-carrier mixture ratio, and the equipment is complicated to maintain and manage, and the overall equipment structure is large. It has the disadvantage that it can easily become

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. One-component developer consists of only toner,
There are also those to which auxiliary agents are externally added as necessary. 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 color image including full color or multicolor is formed using magnetic toner, the developed visible image becomes unclear and a vivid color image cannot be obtained. 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 one-component development method, a one-component developer is carried on a developer carrier and transported, and the developer carrier and the latent image carrier face each other for development. In the area, the electrostatic latent image formed on the latent image carrier is visualized 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 used. It is necessary to convey the latent image to a development area and visualize the latent image using the toner.

When magnetic toner is used, the one-component developer can be supported on the developer carrier using the magnetic force of a magnet installed inside the developer carrier, so the above requirements can be met relatively easily. It is possible to meet the requirements.

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, Japanese Patent Laid-Open No. 61-42672 discloses that a dielectric (insulator) layer is laminated on the surface of a developer carrier (developing roller), and a developer supplying member made of a sponge roller, for example. are brought into pressure contact with each other, triboelectrically charging them to opposite polarities, and electrostatically attaching non-magnetic toner charged to the opposite polarity to the dielectric, and transporting the one-component developer to the development area. A method 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.
It is difficult to carry a large amount of toner on the surface of the developing roller, and the amount of developer that can be transported to the developing area is insufficient, making it difficult to form a high-density visible image.

[0008]Also, a configuration is 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. However, it is difficult to make a sufficient amount of toner adhere to the developing roller.

[0009] As the toner supply member, 102~
106Ω・cm conductive foam (Japanese Patent Application Laid-Open No. 60-2290
No. 57), elastic body with skin layer (Japanese Patent Application Laid-Open No. 60-229
No. 060) and fur brush (Japanese Patent Laid-Open No. 61-426)
It has been proposed to use a metal body with an uneven surface (Japanese Patent Application Laid-Open No. 60-53976), an insulating coated roller body (Japanese Patent Laid-Open No. 55-46768), etc. as a developing roller. A medium-resistance coated roller (Japanese Patent Application Laid-Open No. 58-132768) and an electrode roller having an insulating surface and a conductive surface (Japanese Patent Application Laid-Open No. 53-36245) are disclosed.

Further, in a developing device using a non-magnetic one-component developer, JP-A-60-229057 uses a sponge roller, JP-A-62-229060 uses an elastic roller, and JP-A-61-52663 uses a sponge roller. Using a fur brush or the like, the toner is charged by frictional charging between the toner and the replenishing member, and the toner is electrostatically adhered to the developing roller by the friction in contact with the developing roller. The layer thickness regulating member is used to control the toner layer and 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 friction between the toner replenishing member and the developing roller, but since the friction is caused by the member to which the toner is attached, sufficient charging is not achieved. is difficult to obtain, resulting in insufficient toner adhesion. The requirement for this large amount of deposition also makes one-component development difficult.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 54-51841, after scraping off the one-component developer on the developing roller after passing through the developing area, the surface layer of the developing roller is coated with A technique has also been proposed in which a corona discharge is applied to apply an electric charge, and then non-magnetic toner is electrostatically and actively deposited on the developing roller using a developer supplying member. Also, the amount of developer carried on the surface of the developing roller cannot be increased, and a large amount of developer cannot be conveyed to the developing area.

As a method for solving these problems, the present inventors have previously developed a one-component system consisting of a non-magnetic toner to which an auxiliary agent is added externally to a rotatably driven developer carrier. A developer is supplied, the developer is carried on the surface of the carrier and transported, and a 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. In a developing method in which an electrostatic latent image is visualized by the developer carried on a developer carrier, electric charges are selectively retained on the surface of the developer carrier, so that the electrostatic latent image is visualized in the vicinity of the surface of the developer carrier. An image in which a large number of minute closed electric fields are formed, charged toner is attracted by the closed electric fields, developer is attached and carried on the surface of a developer carrier, and the electrostatic latent image is visualized by the carried developer. ``formation method'' was proposed.

[0014] In this method, since a large number of micro-closed electric fields (micro-fields) 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 sufficiently charged This method has many advantages, such as being able to carry toner on a developer carrier and transport it to a developing area.

[0015]

[Problems to be Solved by the Invention] However, according to subsequent research by the present inventors, it has been found that in the development method that forms a large number of minute closed electric fields (microfields) near the surface of the developer carrier as described above, In this case, it is difficult to always maintain a stable toner layer on the developer carrier with two or more layers, and the toner layer becomes thinner and the amount of toner to be developed decreases, resulting in low density in the image area. The toner layer may become non-uniform, resulting in uneven development or fogging.Furthermore, a filming phenomenon often occurs on the developer carrier, reducing the microfield effect and hindering development. It has been found that the amount of toner retained on the agent carrier decreases, causing problems such as difficulty in sufficiently developing toner onto the latent image carrier.

Therefore, an object of the present invention is to be able to stably and uniformly laminate toner in two or more layers on a developer carrier in the above-mentioned image forming method, and to form a film of toner on the developer carrier. An object of the present invention is to provide an image forming method that can control printing and obtain high-density, high-quality images over a long period of time.

[0017]

[Means for Solving the Problems] As a result of intensive studies, the present inventors have found that it is possible to use a toner that contains a binder resin and a colorant, and further contains a charge control agent made of a compound made of a metal-containing azo dye. The present inventors have found that the above object is met, and have completed the present invention.

That is, according to the present invention, by selectively retaining 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 the developer carrier is A one-component developer consisting of toner to which an auxiliary agent is externally added as necessary is supplied onto the body, the developer is carried on the surface of the developer carrier by the minute closed electric field, and the carried developer causes static An image forming method for visualizing an electrostatic latent image, characterized in that a toner comprising at least a binder resin and a colorant and containing a metal-containing azo dye charge control agent is used. A method is provided.

In the development method that forms a minute closed electric field (micro field), the toner layer on the developer carrier is always stabilized by having two or more layers, and the toner layer becomes thin, causing uneven development and fogging. In order to prevent this from occurring, it is necessary to use a toner that always has stable charging characteristics, but in the present invention, this problem can be solved by using a toner containing a metal-containing azo dye charge control agent. is resolved.

In the toner used in the present invention, a metal-containing azo dye is used as a charge control agent, and specific examples thereof include the compounds shown in Table 1 below. In addition, compound No. Compound Nos. 1 to 321 are examples of charge control agents exhibiting negative charge. 322 to 370 are examples of charge control agents that exhibit positive charge. These may be used alone or in combination.

[0021]

[Table 1-(1)]

As the binder resin used in the toner used in the present invention, all binder resins conventionally used as binder resins for toners can be used. Specifically, monopolymers of styrene and its substituted products such as polystyrene, polychlorostyrene, and polyvinyltoluene; styrene/
p-chlorostyrene copolymer, styrene/propylene copolymer, styrene/vinyltoluene copolymer, styrene/vinylnaphthalene copolymer, styrene/methyl acrylate copolymer, styrene/ethyl acrylate copolymer,
Styrene/butyl acrylate copolymer, styrene/octyl acrylate copolymer, styrene/methyl methacrylate copolymer, styrene/ethyl methacrylate copolymer,
Styrene/butyl methacrylate copolymer, styrene/α
- Methyl chlormethacrylate copolymer, styrene/acrylonitrile copolymer, styrene/vinyl methyl ether copolymer, styrene/vinyl ethyl ether copolymer, styrene/vinyl methyl ketone copolymer, styrene/
butadiene copolymer, styrene/isoprene copolymer,
Styrenic copolymers such as styrene/acrylonitrile/indene copolymer, styrene/maleic acid copolymer, styrene/maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene , polypropylene, polyester, polyvinyl butyral butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. These can be used alone or in combination of two or more.

Further, as the colorant used in the toner used in the present invention, all the pigments and dyes conventionally used as colorants for toners can be used. Specifically, carbon black, lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, calco oil blue,
DuPont Oil Red, Quinoline Yellow, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Hansa Yellow G, Rhodamine 6C Lake,
chrome yellow, quinacridone, benzidine yellow,
Examples include malachite green, malachite green hexalate, oil black, azo oil black, rose bengal, monoazo dyes and pigments, disazo dyes and pigments, and trisazo dyes and pigments.

Furthermore, in the toner used in the present invention,
In order to provide mold release properties, in addition to synthetic waxes such as low molecular weight polyethylene and polypropylene, vegetable waxes such as candelilla wax, carnauba wax, rice wax, tree wax, and jojoba oil; beeswax, lanolin, and whale oil are used. Animal waxes such as wax; Mineral waxes such as montan wax and ozokerite; Hydrogenated castor oil, hydroxystearic acid, fatty acid amide,
It can contain oil-based waxes such as phenol fatty acid esters.

In addition to the above-mentioned binder resin, colorant, etc., the toner used in the present invention may contain various plasticizers ( It is also possible to add auxiliary agents such as dibutyl phthalate, dioctyl phthalate, etc.), resistance adjusters (tin oxide, lead oxide, antimony oxide, etc.). Furthermore, additives other than the above-mentioned binder resin, colorant, auxiliary agent, etc. can also be mixed into the toner of the present invention, if necessary. Examples of such additives include fluidizing agents such as colloidal silica, titanium oxide, and aluminum oxide.

As described above, the image forming method of the present invention forms a large number of minute closed electric fields near the surface of the developer carrier by selectively holding charges on the surface of the developer carrier. , A one-component developer consisting of toner to which an adjuvant is externally added as necessary is supplied onto this developer carrier, and the developer is supported on the surface of the developer carrier by the minute closed electric field. An electrostatic latent image is visualized by a supported developer.

[0027] 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. Figure 1
, the toner 6 contained in the toner tank 70
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 (
The developing roller) 20 rotates in the direction of the arrow (for example, 400
rpm) 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, charges the developer carrier 20 and the toner 60, and causes the toner 60 to adhere to the developer carrier 20. Further, the developer carrier 20 rotates, and the toner adhering to the developer carrier 20 is removed by a toner layer thickness regulating member (elastic blade) 30.
The charging is stabilized while the thickness is controlled, and the developing area 80
reach. In the development area 80, the latent image is developed by contact or non-contact development. Here, if necessary, a bias voltage such as direct current, alternating current, direct current superimposed alternating current, pulse, etc. is applied to the developer carrier 20 and the toner supply member 40.
Optimal images can be controlled.

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, for example, 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 30 to 2000 μm
, preferably 100 to 400 μm in size, are dispersed randomly or according to a certain rule. The area ratio is preferably in the range of 50 to 80% of the area of the dielectric portion.

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 the toner due to the previous development are made constant 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. The electric field on the developer carrier 20 at this time becomes a micro field (closed electric field) as shown in FIG.
This creates an electric field with a large electric field gradient, making it possible to adhere toner in multiple layers. In addition, since the attached toner is in a closed electric field, it is strongly attracted to the developer carrier 20 side.
It becomes difficult to leave.

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. In the electric field between the developer carrier 20 and the electrostatic latent image carrier (photoreceptor) 10 in the development area 80, the electrode effect increases,
The toner on the developer carrier 20 forms an electric field that easily adheres to the electrostatic latent image carrier 10, and development is performed.

Although many types of developing device parts can be used, Table 2 shows the preferred materials based on their releasability with toner and durability.

[0032]

[Table 2]

Next, the method for manufacturing the developer carrier used in the present invention will be explained. For example, the following method is employed. (i) First, a metal roller whose surface is grooved is manufactured. As the groove processing method, a method such as fleur-de-lis knurling is used. 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. [See FIG. 3(a)] (ii) Next, the grooved metal surface is coated with, for example, a fluororesin (Lumiflon LF200; manufactured by Asahi Glass Co., Ltd.), and cured and dried at 100° C. for about 30 minutes. The coating thickness should be such that the grooves are completely filled. [See; Figure 3(b)]
(iii) Subsequently, the surface of the roller is cut or polished so that the conductive surface is mixed in a small area, and the conductive area is reduced to 20 to 50%. [See; Figure 3(c)
]

[0034] In addition to the above-mentioned method, the conductive rubber material having recesses on its surface may be formed by molding, and the recesses may be filled with an insulating material and polished. be able to.

However, in this development method in which a large number of minute closed electric fields (microfields) are formed near the surface of the developer carrier, the toner layer on the developer carrier must always be stabilized by having two or more layers. The toner layer becomes thinner, the amount of toner developed decreases, and the density of the image area becomes low, and the toner layer becomes uneven, resulting in uneven development and the density of the image area becomes uneven. or fog may occur. Additionally, when a filming phenomenon occurs on the developer carrier, filming is formed on the developer carrier, reducing the microfield effect.
The amount of toner held on the developer carrier decreases, making it difficult to sufficiently develop toner onto the latent image carrier.

However, when a toner containing a charge control agent made of the above-mentioned metal-containing azo dye is used, the pulverization of the toner on the developer carrier is suppressed, and as a result, the toner is prevented from being pulverized on the developer carrier. Since filming is suppressed, a sufficient microfield effect is exhibited, and the method of the present invention allows high-density, high-quality images to be obtained over a long period of time.

[0037]

[Examples] The present invention will be explained in more detail with reference to Examples below. Note that parts represent parts by weight.

Example 1 Binder resin Styrene/acrylic copolymer 95 parts
Mold release agent Low molecular weight polypropylene

Part 5 Colorant Carbon black

8 parts Charge control agent Exemplary compound (1)
2.5 parts

The mixture having the above composition was melt-kneaded, cooled, and coarsely pulverized using a hammer mill, and then finely pulverized using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 11μ.
It was set as m. A toner was obtained by adding and mixing 0.2 parts of colloidal silica to 100 parts of the present particles.

Next, a developing roller [FIG. 3(a)] having a cross section as shown in FIG. 3(c) (a dielectric portion made of epoxy-modified silicone resin and a conductive portion are mixed in a minute area, Prepare a developing device (a modified FT4420 machine with an area ratio of 50%) and an inorganic photoreceptor (selenium-based), install the toner in the developing device, and
When an image was formed by applying a charging potential of 0 V, a clear image with high image density and no background stain was obtained. Furthermore,
Even after continuous running of 5,000 sheets, no toner was filmed on the developing roller, and a clear image was maintained.

Example 2 Binder resin Styrene/acrylic copolymer 95 parts
Mold release agent Low molecular weight polypropylene

Part 5 Colorant Carbon black

8 parts Charge control agent Exemplary compound (2)
2.5 parts

The mixture having the above composition was melt-kneaded, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 12μ.
It was set as m. Titanium oxide: 0.3 parts per 100 parts of this particle
A toner was obtained by adding and mixing the following parts.

Next, when the toner was installed in the developing device used in the example and an image was produced, a clear image with high image density and no background stain was obtained. Furthermore, 50 consecutive
Even in the running of 00 sheets, no toner was filmed on the developing roller, and a clear image was maintained.

Example 3 Binder resin Styrene/acrylic copolymer 95 parts
Mold release agent Low molecular weight polypropylene
Part 5 Colorant Carbon black
8 parts Charge control agent Exemplary compound (81)
2.5 parts

The mixture having the above composition was melt-kneaded, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 11 μm.
And so. 0 parts of colloidal silica per 100 parts of this particle
．． Two parts were added and mixed to obtain a toner.

Next, when the toner was installed in the developing device used in Example 1 and an image was produced, a clear image with high image density and no background stain was obtained. Furthermore, 5 consecutive
Even during the running of 000 sheets, no toner was filmed on the developing roller, and a clear image was maintained.

Example 4 Binder resin Styrene/acrylic copolymer 95 parts
Mold release agent Low molecular weight polypropylene
Part 5 Colorant Carbon black
8 parts Charge control agent Exemplary compound (90)
2.5 parts

The mixture having the above composition was melt-kneaded, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 12 μm.
And so. A toner was obtained by adding and mixing 0.3 parts of titanium oxide to 100 parts of the present particles.

Next, when the toner was installed in the developing device used in Example 1 and an image was produced, a clear image with high image density and no background stain was obtained. Furthermore, 5 consecutive
Even during the running of 000 sheets, no toner was filmed on the developing roller, and a clear image was maintained.

Example 5 Binder resin Styrene/acrylic copolymer 95 parts
Mold release agent Low molecular weight polypropylene
Part 5 Colorant Carbon black
8 parts Charge control agent Exemplary compound (106)
2.5 parts

[0051] The mixture having the above composition was melt-kneaded, cooled, and coarsely ground using a hammer mill.
Then, it was pulverized using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 11 μm. 0.0 parts of colloidal silica per 100 parts of this particle.
Two parts were added and mixed to obtain a toner.

Next, the toner was installed in the developing device used in Example 1 and an image was produced, and a clear image with high image density and no background stain was obtained. Furthermore, 5 consecutive
Even during the running of 000 sheets, no toner was filmed on the developing roller, and a clear image was maintained.

Example 6 Binder resin Styrene/acrylic copolymer 95 parts Mold release agent Low molecular weight polypropylene
Part 5 Colorant Carbon black
8 parts Charge control agent
Exemplary compound (189)
Part 3

The mixture having the above composition was melt-kneaded, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 12 μm. A toner was obtained by adding and mixing 0.3 parts of titanium oxide to 100 parts of the present particles.

Next, when the toner was installed in the developing device used in Example 1 and an image was produced, a clear image with high image density and no background stain was obtained. Furthermore, 5 consecutive
Even during the running of 000 sheets, no toner was filmed on the developing roller, and a clear image was maintained.

Example 7 Binder resin Styrene/acrylic copolymer 95 parts Mold release agent Low molecular weight polypropylene
Part 5 Colorant Carbon black
8 parts Charge control agent
Compound example (249)
Part 3

The mixture having the above composition was melt-kneaded, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 11 μm. A toner was obtained by adding and mixing 0.2 parts of colloidal silica to 100 parts of the present particles.

Next, when the toner was installed in the developing device used in Example 1 and an image was produced, a clear image with high image density and no background stain was obtained. Furthermore, 5 consecutive
Even during the running of 000 sheets, no toner was filmed on the developing roller, and a clear image was maintained.

Example 8 Binder resin Styrene/acrylic copolymer 95 parts Mold release agent Low molecular weight polypropylene
Part 5 Colorant Carbon black
8 parts Charge control agent
Compound examples (300)
Part 3

The mixture having the above composition was melt-kneaded, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 12 μm. A toner of the present invention was obtained by adding and mixing 0.3 parts of titanium oxide to 100 parts of the present particles.

Next, when the toner was installed in the developing device used in Example 1 and an image was produced, a clear image with high image density and no background stain was obtained. Furthermore, 5 consecutive
Even during the running of 000 sheets, no toner was filmed on the developing roller, and a clear image was maintained.

Example 9 Binder resin Styrene/acrylic copolymer 95 parts Mold release agent Low molecular weight polypropylene
Part 5 Colorant Carbon black
8 parts Charge control agent
Compound example (315)
Part 3

The mixture having the above composition was melt-kneaded, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 11 μm. A toner was obtained by adding and mixing 0.2 parts of colloidal silica to 100 parts of the present particles.

Next, when the toner was installed in the developing device used in Example 1 and an image was produced, a clear image with high image density and no background stain was obtained. Furthermore, 5 consecutive
Even during the running of 000 sheets, no toner was filmed on the developing roller, and a clear image was maintained.

Example 10 Binder resin Styrene/acrylic copolymer 95 parts Mold release agent Low molecular weight polypropylene
Part 5 Colorant Carbon black
8 parts Charge control agent
Compound example (335)
3.5 parts

The mixture having the above composition was melt-kneaded, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 12 μm. A toner was obtained by adding and mixing 0.3 parts of titanium oxide to 100 parts of the present particles.

Next, a developing roller (FIG. 3(a)) having a cross section as shown in FIG. 3(c) (a dielectric part and a conductive part coexist in a small area, and their area ratio is 50%) A developing device (a modified FT4530) equipped with a photoconductor (OPC)
)), and installing the toner in the developing device,
When a charging potential of -750 V was applied to produce an image, a clear image with high image density and no background stain was obtained. Furthermore, even during continuous running of 5,000 sheets, no toner was filmed on the developing roller, and clear images were maintained.

Comparative Example A toner for comparison was prepared in the same manner as in Example 1 except that no charge control agent was added, and the toner was charged into the same developing device as in Example 1. However, when an image was produced under similar conditions, the image had a low density and a lot of background stains.

[0070]

Effects of the Invention Since the image forming method of the present invention uses a toner containing a charge control agent made of the metal-containing azo dye described above, a large number of micro-closing particles are formed near the surface of the developer carrier. In the development method that forms an electric field, two or more layers of toner can be stably and uniformly stacked on the developer carrier, and toner filming on the developer carrier is suppressed, resulting in high concentration and high quality over a long period of time. images can be obtained.

[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 that forms a microfield electric field on a developer carrier useful for carrying out the present invention.

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. 1; FIG.

3A to 3C are schematic cross-sectional views showing the surface state of a developer carrier used in the developing device of the type shown in FIG. 1 during the manufacturing process.

[Explanation of symbols]

10 Electrostatic latent image carrier 20 Toner conveyance member 30 Toner layer thickness regulating member 40 Toner supply member 50 Stirring blade 60 Toner 70 Toner tank 80 Development area

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[Table 1-86)]

[Table 1-(87)]

[Table 1-(88)]

[Table 1-(89)]

[Table 1-(90)]

[Table 1-(91)]

[Table 1-(92)]

[Table 1-(93)]

[Table 1-(94)]

[Table 1-(95)]

[Table 1-(96)]

Claims (1)

[Claims] Claim 1: By selectively retaining 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 required, Accordingly, a one-component developer consisting of a toner externally added with an adjuvant 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 made visible by the carried developer. In the image forming method, as a toner,
An image forming method comprising using at least a binder resin and a colorant, and containing a metal-containing azo dye charge control agent.