JPH04282644A - Image forming method - Google Patents

Abstract

PURPOSE:To provide the image forming method comprising laminating >=2 toner layers stably and uniformly on a developer carrying sleeve, developing an electrostatic latent image, and obtaining a high-density and high-quality image. CONSTITUTION:A large number of fine closed electric fields are formed near the surface of the developer carrying sleeve by electrically and selective by charging the surface of the sleeve, and the one-component type developer is fed on the sleeve to develop the electrostitc latent image on a latent image carrying drum 10. Some of the following group of compounds is added to the developer as a negative polarity controller: (1) salicylaldimine or alkylsalicylaldimine chelate compound, (2) salicylamine or alkylsalicylamine chelate compound, (3) salicylaldehyde or alkylsalicylaldehyde chelate compound, and (4) salicylaldoxime or alkylsalicylaldoxime chelate compound.

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 powdered developers, two-component developers containing toner and a carrier, and one-component developers that do not contain a carrier are known. The former two-component development method using a two-component developer can produce relatively stable and good recorded images, but on the other hand, it is prone to carrier deterioration and fluctuations in the toner and carrier mixing ratio, making it difficult to maintain and manage the equipment. However, this method has the disadvantage that it is complicated and the structure of the entire device tends to increase in size.

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. JP-A-58-132768), an electrode roller having an insulating surface and a conductive surface (JP-A-53-36245), and the like have been 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 documents, 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.

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 positively adhered to the developing roller by a developer supplying member. It is not possible to increase the amount of developer carried on the surface of the developing roller, and it is not possible to convey a large amount of developer 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. It has been found that problems arise, such as the amount of toner held on the developer carrier decreases, making it difficult to sufficiently develop the 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] The image forming method of the present invention creates a minute closed electric field near the surface of the developing roller by selectively retaining electric charge on the surface of the developing roller, and the developer is carried on the developing roller. (1) A chelate compound of salicylaldimine or alkylsalicylaldimine represented by the general formula (I) shown below (the chelate-forming metal is Ni, Zn, Cr) as a binder resin, a colorant, and a charge control agent. ,Co,F
e or Cu. )

[Chemical Formula 1] (R1, R2, and R3 may be the same or different at the same time and are a hydrogen atom or an alkyl group having 1 to 24 carbon atoms.) (2) General formula (II) of Chemical Formula 2 below A chelate compound of salicylamine or alkyl salicylamine represented by (
Chelate forming metals are Ni, Zn, Cr, Co, Fe, C
d or Cu. )

[Chemical formula 2] (R1, R2, R3 are the same as in general formula (I).) (
3) A chelate compound of salicylaldehyde or alkyl salicylaldehyde represented by the general formula (III) shown below (chelate-forming metals include Ni, Zn, Cr, Co,
Fe, Cd, Mn, Ti, Al, Mg, Ba, Zr, T
h or Cu. )

embedded image (R1, R2, and R3 are the same as in general formula (I)) or (4) a chelate compound of salicylaldoxime or alkyl salicylaldoxime represented by general formula (IV) of the following chemical formula (4) ( Chelate-forming metals include Ni, Zn, Cr,
Co, Fe, Cd, Mn, Ti, Al, Mg, Ba, Z
r, Th or Cu. )

[Chemical formula 4] (R1, R2, R3 are the same as those in general formula (I).) A one-component system consisting of a toner containing at least one of the following, and optionally supplemented with an auxiliary agent. Supplying a developer, causing the developer to be carried on the surface of the developer carrier by the minute closed electric field, and visualizing the electrostatic latent image on the latent image carrier by the carried developer. It is a feature.

[0018] The method of the present invention will be explained in more detail below. In the developing method of the present invention that forms a minute closed electric field (micro field), the toner layer on the developing roller is always stabilized by having two or more layers. In order to prevent the toner layer from becoming thinner, resulting in uneven development and fogging, a toner that always has stable charging characteristics is required. Therefore, it is effective to use the above-mentioned chelate compounds as the charge control agent (negative polarity control agent) used in the present invention.

(1) Specific examples of chelate compounds represented by general formula (I) (chelate-forming metals: Ni, jZr, C
r, Co, Fe, Cu), its ligands include salicylaldimine 3-methylsalicylaldimine 3-ethylsalicylaldimine 3-n-butylsalicylaldimine 3-stearylsalicylaldimine 5-methylsalicylaldimine 5-ethylsalicylaldimine 5- t-Butylsalicylaldimine 5-uralylsalicylaldimine 3,5-dimethylsalicylaldimine 3,5-diethylsalicylaldimine 3-methyl-5-ethylsalicylaldimine 3-methyl-5-t-butylsalicylaldimine 3-ethyl-5 −
Examples include n-butylsalicylaldimine 3-methyl-5-uralylsalicylaldimine 3-ethyl-5-stearylsalicylaldimine 3,5-di-t-butylsalicylaldimine.

(2) Specific examples of chelate compounds represented by general formula (II) (chelate-forming metals: Zn, Cu, N
i, Co, Cd, Cr, Fe), its ligands include salicylamine 3-methylsalicylamine 3-ethylsalicylamine 3-isopropylsalicylamine 3-n-butylsalicylamine 3-stearylsalicylamine 5-methylsalicylamine 5-ethylsalicylamine 5-n-propylsalicylamine 5-t-butylsalicylamine 5-laurylsalicylamine 3,5-dimethylsalicylamine 3,5-diethylsalicylamine 3,5-di-n-propylsalicylamine 3 -Methyl-
5-ethylsalicylamine 3-methyl-5-t-butylsalicylamine 3-ethyl-5-t-butylsalicylamine 3-methyl-5-laurylsalicylamine 3-ethyl-5-stearylsalicylamine 3,5-di -t-butylsalicylamine and the like.

(3) Specific examples of chelate compounds represented by general formula (III) (chelate-forming metals: Co, Ni,
Cu, Zn, Cd, Fe, Cr, Mn, Ti, Al, M
g, Ba, Zr, Th), the ligands include salicylaldehyde 4-methylsalicylaldehyde 4,6-di-t-butylsalicylaldehyde 4-n-propylsalicylaldehyde 5-t-butylsalicylaldehyde 3,5- Examples include di-t-butylsalicylaldehyde. In some cases, halogen ions, perchlorate ions,
It may be one that can form a complex salt with borofluoride ions or the like.

(4) Specific examples of chelate compounds represented by general formula (IV) (chelate-forming metals: Co, Ni, C
u, Zn, Cd, Fe, Cr, Mn, Ti, Al, Mg
, Ba, Zr, Th), the ligand is salicylaldoxime 5-methylsalicylaldoxime 3,5-di-t-butylsalicylaldoxime 5-n-
Examples include propyl salicylaldoxime.

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 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. It can contain animal waxes such as wax; mineral waxes such as montan wax and ozokerite; oil-based waxes such as hydrogenated castor oil, hydroxystearic acid, fatty acid amides, and phenol fatty acid esters.

Toner used in the present invention (negatively chargeable toner)
In addition to the above-mentioned binder resin, colorant, etc., various plasticizers (dibutyl phthalate, dioctyl phthalate, etc.) are used to adjust the thermal properties, electrical properties, physical properties, etc. of the toner as necessary. ), resistance modifiers (tin oxide, lead oxide, antimony oxide, etc.) and other auxiliary agents can also be added. 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 retaining 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.

The 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 1 shows the preferred materials based on their releasability with toner and durability.

[0033]

[Table 1]

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 a silicone resin and cured and dried. The coating thickness should be such that the grooves are completely filled. [See FIG. 3(b)] (iii) Next, 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)
]

[0035] In addition to the above-mentioned method, the conductive rubber material having concavities on its surface may be formed by molding, and the concavities 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, it is necessary to always stabilize the toner layer on the developer carrier by forming 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 chelate compound is used, the pulverization of the toner on the developer carrier is suppressed, and as a result, filming on the developer carrier occurs. is suppressed, a sufficient microfield effect is exhibited, and the method of the present invention makes it possible to obtain high-density, high-quality images over a long period of time.

[0038]

[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

Part 8 Charge control agent Co chelate of salicylaldimine
Two parts of the mixture having the above composition were melt-kneaded, cooled, and 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 about 11 μm. This particle 100
0.2 part of colloidal silica was added and mixed to obtain a negatively chargeable toner.

Next, a developing roller [FIG. 3(a)] having a cross section as shown in FIG. 3(c) (a dielectric part made of epoxy-modified silicone resin and a conductive part are mixed in a small area) , the area ratio of which is 50%) is prepared (a part of the developing section of Ricoh FT4200 is modified), and the toner is installed in the developing device,
Image was produced (+800 using selenium photoreceptor)
When developing was performed by applying a charging potential of V), a clear image with high image density and no background stain was obtained. Further, even after running 5000 sheets continuously, 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 3,5-
Fe chelate of di-t-butylsalicylaldimine
Two parts of the mixture having the above composition were melt-kneaded, cooled, and 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 about 12 μm. A negatively chargeable toner was obtained by adding and mixing 0.3 parts of titanium oxide to 100 parts of the present particles. Next, when an image was produced in the same manner as in Example 1, similar results were obtained.

Binder resin styrene/acrylic copolymer 95 parts
Mold release agent Low molecular weight polypropylene

Part 5 Colorant Carbon black

8 parts Charge control agent Co chelate of salicylamine
Two parts of the mixture having the above composition were melt-kneaded, cooled, and 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 about 11 μm. This particle 1
0.00 parts of colloidal silica was added and mixed to obtain a negatively chargeable toner. Next, when an image was produced in the same manner as in Example 1, similar results were obtained.

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 Co chelate of 5-methylsalicylamino
Two parts of the mixture having the above composition were melt-kneaded, cooled, and 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 about 12 μm. Add and mix 0.3 parts of colloidal silica to 100 parts of the present particles,
A negatively chargeable toner was obtained. Next, when an image was produced in the same manner as in Example 1, similar results were obtained.

Example 5 Binder resin Styrene/acrylic copolymer 95 parts
Mold release agent Low molecular weight polypropylene

Part 5 Colorant Carbon black

Part 8 Charge control agent Cu chelate of salicylaldehyde
Two parts of the mixture having the above composition were melt-kneaded, cooled, and 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 about 11 μm. This particle 100
0.2 part of colloidal silica was added and mixed to obtain a negatively chargeable toner. Next, when an image was produced in the same manner as in Example 1, similar results were obtained.

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 3,5-
Fe chelate of di-t-butylsalicylaldehyde
Two parts of the mixture having the above composition were melt-kneaded, cooled, and 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 about 12 μm. A negatively chargeable toner was obtained by adding and mixing 0.3 parts of colloidal silica to 100 parts of the present particles. Next, when an image was produced in the same manner as in Example 1, similar results were obtained.

Example 7 Binder resin Styrene/acrylic copolymer 95 parts
Mold release agent Low molecular weight polypropylene

Part 5 Colorant Carbon black

Part 8 Charge control agent Ni chelate of salicylaldoxime
Two parts of the mixture having the above composition were melt-kneaded, cooled, and 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 about 11 μm. Add and mix 0.2 parts of colloidal silica to 100 parts of this particle,
A negatively chargeable toner was obtained. Next, when an image was produced in the same manner as in Example 1, similar results were obtained.

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 3,5,
- 2 parts of Ni chelate of di-t-butylsalicylaldoxime 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 about 12 μm. A negatively chargeable toner was obtained by adding and mixing 0.3 parts of colloidal silica to 100 parts of the present particles. Next, when an image was produced in the same manner as in Example 1, similar results were obtained.

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 images were produced in the same manner as in Example 1. A high-density image was not obtained, and some background staining was observed.

[0049]

According to the image forming method of the present invention, two or more layers of toner can be stably and uniformly laminated on a developer carrier, and toner filming on the developer carrier can be suppressed. High-density, high-quality images can be obtained over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view centered on a developer carrier portion showing an example of a developing device 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

Claims (4)

[Claims] Claim 1: By selectively retaining charges on the surface of the developing roller, a minute closed electric field is formed near the surface of the developing roller, and the binder resin, colorant, and charged particles are formed on the developer carrier. A chelate compound of salicylaldimine or alkylsalicylaldimine represented by the following general formula 1 as a control agent (chelate-forming metals include Ni, Zn,
A one-component developer consisting of a toner containing at least one type of toner (selected from Cr, Co, Fe, or Cu) and optionally supplemented with an auxiliary agent is supplied, and the minute closed electric field causes the An image forming method characterized by carrying a developer on the surface of a developer carrier and visualizing an electrostatic latent image on the latent image carrier by the carried developer. [Chemical formula 1] (R1, R2, and R3 may be the same or different at the same time, and are a hydrogen atom or an alkyl group having 1 to 24 carbon atoms.) 2. By selectively retaining charges on the surface of the developing roller, a minute closed electric field is formed near the surface of the developing roller, and the binder resin, colorant, and charged particles are formed on the developer carrier. A chelate compound of salicylamine or alkyl salicylamine represented by the following general formula 2 as a control agent (chelate-forming metals include Ni, Zn, Cr, C
o, Fe, Cd or Cu)
Supplying a one-component developer consisting of a toner containing a seed and externally adding an auxiliary agent if necessary, and causing the developer to be supported on the surface of the developer carrier by the minute closed electric field, and the developer being supported. An image forming method characterized by visualizing an electrostatic latent image on a latent image carrier using a developer. embedded image (R1, R2, and R3 may be the same or different and are a hydrogen atom or an alkyl group having 1 to 24 carbon atoms.) 3. By selectively holding charges on the surface of the developing roller, a minute closed electric field is formed near the surface of the developing roller, and the binder resin, colorant, and charged particles are formed on the developer carrier. A chelate compound of salicylaldehyde or alkylaldehyde represented by the following general formula 3 as a control agent (chelate-forming metals include Ni, Zn, Cr, C
o, Fe, Cd, Mn, Ti, Al, Mg, Ba, Zr
, Th, or Cu), and if necessary, an auxiliary agent is externally added to the toner. An image forming method characterized by carrying a developer on the surface of a developer carrier and visualizing an electrostatic latent image on the latent image carrier using the carried developer. embedded image (R1, R2, and R3 may be the same or different at the same time and are a hydrogen atom or an alkyl group having 1 to 24 carbon atoms.) 4. By selectively retaining charges on the surface of the developing roller, a minute closed electric field is formed near the surface of the developing roller, and the binder resin, colorant, and charged particles are formed on the developer carrier. A chelate compound of salicylaldoxime or alkylaldoxime represented by the following general formula 4 as a control agent (the chelate-forming metal is Ni, Zn, Cr).
, Co, Fe, Cd, Mn, Ti, Al, Mg, Ba,
A one-component developer consisting of a toner containing at least one of Zr, Th, or Cu (selected from Zr, Th, or Cu) and optionally externally added with an auxiliary agent is supplied, and the minute closed electric field causes the developer to 1. An image forming method characterized by carrying on the surface of a developer carrier, and visualizing an electrostatic latent image on the latent image carrier with the carried developer. embedded image (R1, R2, and R3 may be the same or different and are a hydrogen atom or an alkyl group having 1 to 24 carbon atoms.)