JP3365014B2 - Image forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for developing an electrostatic latent image formed on an image bearing member having a surface layer with toner.

[0002]

2. Description of the Related Art In recent years, an image forming method of developing an electrostatic latent image formed on a photoconductor having a surface layer with toner has been attracting attention. For example, in the electrophotographic field, a technique of forming an electrostatic latent image on a photoreceptor having a carbon-based high hardness coating layer as a surface layer and developing the electrostatic latent image with a toner containing a resin component and a colorant (for example, a special technique). Kaisho 61-25154
And JP-A-63-97962). Such a carbon-based high-hardness coating layer has a high hardness and has an advantage that the photoconductor is not scraped even if the image forming process is repeated many times.

However, a photoreceptor having a carbon-based high hardness coating layer as a surface layer, for example, a photoreceptor including a surface layer of amorphous silicon carbide and a photosensitive layer made of amorphous silicon, or an amorphous hydrocarbon film. When the image forming process is repeatedly carried out by using a photoreceptor including a photosensitive layer composed of the surface layer and the organic photosensitive layer, a problem of image deletion occurs. This problem remarkably occurs especially in a high humidity environment. Since the surface layer of the above-mentioned photoconductor hardly undergoes film scraping, as the image forming process is repeated, charge generation of nitrates and the like based on nitrogen oxides (NOx) generated in the charging step for uniformly charging the photoconductor Objects accumulate on the surface layer. Due to this charging product, the resistance of the surface layer of the photoconductor is lowered, and image deletion gradually occurs especially in a high humidity environment.

A photoreceptor having a carbon-based high hardness coating layer has a tendency that the residual potential tends to increase due to the low mobility of the coating layer, and therefore, when repeated image formation is performed. Fog and toner on white background are likely to occur.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method which solves the above problems.

That is, even when the image forming process is repeated by using an image bearing member having a high hardness carbon-based high hardness coating layer as a surface layer, an image forming method which does not cause image deletion or fog on a white background is provided. The challenge is to provide.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a toner obtained by fixing magnetic fine particles on the surface of a toner particle and externally adding post-treated fine particles is used. The present invention relates to an image forming method for developing an electrostatic latent image formed on an image carrier having a hardness coating layer as a surface layer.

[0008]

In the present invention, after the magnetic fine particles are fixed on the surface of the toner particles , the toner having the carbon-based high hardness coating layer as the surface layer is used on the image carrier using the toner to which the post-treated fine particles are externally added. It was found that the problem of image deletion can be solved by developing the electrostatic latent image. The reason why the image deletion is eliminated by using such a specific developer is not always clear, but it is considered as follows.

That is, in the present invention, the post-treatment fine particles are externally added to the toner particles, which means that the fine particles are movably interposed as a lubricant between the toner particles and the surface layer of the image carrier. At this time, the fine particles rub against the surface layer of the image bearing member, and by this physical rubbing force,
It has the effect of mechanically and physically scraping and removing the charged products accumulated on the surface layer. However, since the toner particles contain the fixing component, the externally added fine particles are buried in the toner particles together with the printing durability, so that the scraping removal effect cannot be sufficiently exerted. The present inventors have completed the present invention by finding that it is effective to immobilize the magnetic fine particles on the surface of the toner particles in order to prevent the fine particles from being buried due to the printing durability. That is, the surface of the toner particles can be apparently hardened by the magnetic particles that have been subjected to the immobilization treatment, so that the externally added particles are prevented from being buried.

Further, the image bearing member having the carbon-based high hardness coating layer tends to increase the residual potential due to the low mobility of the coating layer. In addition, fog in the white background and toner scattering easily occur. On the other hand, by using magnetic fine particles as the fine particles to be fixed, the magnetic binding force of the toner to the developing roller, which is the developer carrier, can be increased and fogging and toner scattering can be prevented.

In the present invention, the term "immobilization treatment" means a state in which at least a part of the magnetic fine particles is embedded in the toner particles and fixed, preferably 30 times the volume of the magnetic fine particles. It is desirable that at least 100% be embedded and fixed in the toner particles.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic structure of an image forming apparatus for carrying out the image forming method of the present invention. 1 is a photosensitive drum, 2 is a corona charger, 3 is exposure light, 4 is a developing device, and 5 is transfer. paper,
6 is a transfer charger, 7 is a separation charger, 8 is a cleaning device, 9 is an eraser lamp, and 10 is a fixing device.

The photoconductor drum 1 is uniformly charged by the corona charger 2, and then exposed to the exposure light 3 based on the image information to form an electrostatic latent image on the surface thereof. The electrostatic latent image is subsequently developed by the toner described later stored in the developing device 4, the obtained toner image is transferred onto the transfer paper 5 by the transfer charger 6, and the transfer paper 5 having the toner image is separated from the separation charger 7. Is peeled off from the photosensitive drum 1.
The toner image held on the transfer paper 5 is fixed by the fixing device 10 to obtain a fixed image. On the other hand, after the transfer paper 5 is peeled off, the residual toner is removed by the blade of the cleaning device 8 and the residual charge is removed by the eraser lamp 9 to prepare for the next image formation.

As the toner stored in the developing device 4,
The toner obtained by fixing the magnetic fine particles on the surface and externally adding the post-treated fine particles is used.

As the magnetic fine particles used for the immobilization treatment, a metal showing a ferromagnetic material such as cobalt, iron or nickel,
Alloys of metals such as aluminum, cobalt, iron, lead, magnesium, nickel, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures and oxides thereof, fired bodies (ferrite) Known magnetic fine particles such as).

As these magnetic fine particles, it is desirable to use primary particles having a volume average particle diameter of 0.01 to 2 μm. The addition amount of the magnetic fine particles is preferably such that the surface of the toner is sufficiently covered with the magnetic fine particles, and is preferably about 1.0 to 10% by weight based on the toner particles.

Further, when the magnetic fine particles are subjected to a hydrophobizing treatment with a hydrophobizing agent such as a silane coupling agent, a titanium coupling agent, a higher fatty acid, or silicone oil, the change of the toner characteristics due to the change of use environment is suppressed. It is possible to do so, which is preferable.

Further, in the present invention, as a concrete apparatus for immobilizing the magnetic fine particles on the toner surface, a Henschel mixer (manufactured by Mitsui Miike Kakoki Co., Ltd.), a hybridizer (manufactured by Nara Machinery Co., Ltd.), a homogenizer (Japan Seiki Co., Ltd.), Kryptron System (Kawasaki Heavy Industries Co., Ltd.), Turbo Mill (Tabo Kogyo Co., Ltd.), and the like. Using these devices, a part of the magnetic fine particles is embedded and fixed in the toner bulk.

If the fixing treatment is not carried out in this manner, the magnetic fine particles are detached from the surface of the toner particles , and the externally added fine particles are buried in the toner particles in the detached portion as described above. There is a disadvantage that the effect of scraping and removing that the added fine particles cannot fully bring out.

The post-treated fine particles added externally in the present invention include silica, titanium dioxide, alumina, magnesium fluoride, silicon carbide, boron carbide, titanium carbide, zirconium carbide, boron nitride, titanium nitride, zirconium nitride, magnetite, Inorganic fine particles having a volume average particle diameter of about 0.01 to 5 μm, such as molybdenum disulfide, can be exemplified.

Further, when these inorganic fine particles are subjected to a hydrophobizing treatment with a hydrophobizing agent such as a silane coupling agent, a titanium coupling agent, a higher fatty acid, and silicone oil,
This is preferable because it is possible to suppress changes in toner characteristics due to changes in the use environment.

Not only the inorganic fine particles, but also styrene, acrylic, methacrylic, benzoguanamine, silicon granulated by a wet polymerization method such as emulsion polymerization, soap-free emulsion polymerization, non-aqueous dispersion polymerization, or gas phase polymerization method. Examples include various organic fine particles having a volume average particle diameter of about 0.01 to 5 μm, such as Teflon, polyethylene, and polypropylene.

The amount of the post-treatment fine particles added to the toner particles is such that the fluidity required for the toner is imparted and the charged products accumulated on the surface layer of the image carrier are scraped off. On the other hand, it is preferable to add about 0.05 to 5% by weight, preferably about 0.1 to 3% by weight.

Further, in the present invention, in order to externally add the fine particles to the toner, the toner particles to which the magnetic fine particles have been fixed and the fine particles for external addition may be mixed and processed. Examples thereof include Henschel mixer, homogenizer, Hi-X (manufactured by Nippon Steel Industrial Co., Ltd.) and the like. From the viewpoint of process simplification, cost reduction, etc., use the same device as the device used for immobilization processing and external addition processing, and perform immobilization processing and external addition processing by controlling the processing conditions such as rotation speed. Is desirable.

As described above, the effect of scraping and removing the charged product accumulated on the surface layer of the image bearing member cannot be achieved unless the fine particles are externally added. Further, if the fine particles are not externally added, the fluidity of the toner is significantly reduced, which causes a disadvantage that stable toner cannot be supplied to the developing unit.

Further, in the present invention, an image bearing member having a carbon-based high hardness coating layer is used.

In the present invention, the carbon-based high hardness coating layer means
It is defined as the outermost surface layer of the image carrier having a Vickers hardness of 50 or more and a ratio of the number of carbon atoms in the total number of atoms of 30% or more. Further, as the carbon-based high hardness coating layer, one having a Vickers hardness of 300 or more is preferable from the viewpoint of durability. Specific examples thereof include an amorphous hydrocarbon film, an amorphous silicon carbide film, a resin film made of a resin such as polyester, polyurethane, and polyamide, or a copolymer containing these resin components. Among them, the amorphous hydrocarbon film is preferable from the viewpoint of durability and the film forming property on the organic photosensitive layer which is low in cost and high in performance.

As a specific manufacturing method for obtaining the carbon-based high hardness coating layer, dry processes such as plasma CVD method, sputtering method, vacuum deposition method, etc., wet processes such as dip coating method, dipping method, spray method, etc. Can be illustrated.

In the present invention, an image bearing member having a carbon-based high hardness coating layer as a surface layer means an electrophotographic photoreceptor having the above-mentioned carbon-based high hardness coating layer as the outermost surface, or an ion flow system or the like. Examples thereof include those having the above-mentioned carbon-based high hardness coating layer as the outermost surface layer of the dielectric used in the system in which the electrostatic latent image is formed on the image carrier.

As an image bearing member having a specific carbon-based high hardness coating layer as a surface layer, a photoreceptor including a surface layer of amorphous silicon carbide and a photosensitive layer composed of amorphous silicon, or an amorphous carbon Examples thereof include a photoreceptor including a photosensitive layer including a surface layer of a hydrogen film and an organic photosensitive layer. Note that these photoreceptors tend to have a serious image smearing and fog in the white background as well as the printing durability. However, by carrying out the image forming method of the present invention, the image smearing and the fog in the white background can be prevented.

The toner applicable to the present invention may be any toner obtained by immobilizing magnetic fine particles on the surface and externally adding post-treated fine particles as described above. Known components can be used as the other components.

Examples of the binder resin include styrene resin, acrylic resin, methacrylic resin, styrene-acrylic resin, styrene-butadiene resin, olefin resin, polyester resin, epoxy resin, urethane resin, amide resin. A resin, a thermoplastic resin such as a phenolic resin or a thermosetting resin, and a copolymer, a block polymer, a graft polymer or a polymer blend thereof can be used.

In such a resin, the number average molecular weight Mn and the molecular weight distribution (Mw / Mn: weight average molecular weight Mw) are 1000 ≦ Mn ≦ 20000 and 2 ≦ M.
It is desirable to use w / Mn ≦ 80 and further, for the number average molecular weight, 2000 ≦ Mn ≦ 15000. Further, the glass transition point of the resin is 55 ° C to
It is desirable to use one having a softening point of 70 ° C. and a softening point of 80 ° C. to 140 ° C.

As the colorant, black pigments include carbon black, copper oxide, manganese dioxide, aniline black,
Activated carbon, ferrite, magnetite and the like can be used.

The yellow pigments include yellow lead, zinc yellow,
Cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, bunzer yellow G, bunzer yellow 10G, benzidine yellow G, benzidine yellow GR, quinoline yellow rake, permanent yellow NCG, tartrazine rake. Etc. can be used.

As the red pigment, red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange GK, red iron oxide, cadmium red, red lead, permanent red 4R, resole red, pyrazolone red. , Watching Red, Lake Red C, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, Permanent Orange GTR, Balkan Fast Orange GG, Permanent Red F4.
RH, permanent carmine FB, etc. can be used.

As the blue pigment, dark blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue and the like can be used.

The amount of these colorants is 1 to 20 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of the resin in the toner.

As the anti-offset agent, a low molecular weight polyethylene wax, a low molecular weight oxidized polyethylene wax, a low molecular weight polypropylene wax, a low molecular weight oxidized polypropylene wax, a higher fatty acid wax, a higher fatty acid ester wax, a sazol wax, etc. may be used alone or in combination. A mixture of more than one type can be used.

The offset preventive agent is used in an amount of 1 to 15 parts by weight, preferably 2 to 8 parts by weight, based on 100 parts by weight of the resin in the toner.

When the magnetic fine particles are internally added to the toner, 1 to 80 parts by weight, preferably 5 to 60 parts by weight of the above-mentioned magnetic fine particles are used with respect to 100 parts by weight of the resin in the toner. Good.

As the charge control agent, as a positive charge control agent, nigrosine base EX, a quaternary ammonium salt,
A polyamine compound, an imidazole compound, etc. can be used.

On the other hand, as the negative charge control agent, a chromium complex salt type azo dye, a copper phthalocyanine dye, a chromium complex salt, a zinc complex salt, an aluminum complex salt, a calixarene compound or the like can be used.

The amount of these charge control agents is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the resin in the toner.

The volume average particle diameter of the toner is 5 to 20 μm.
m is good. This is because if it is too small, cleaning failure will occur, and if it is too large, the resolution of the obtained copy image will decrease and toner scattering will increase. When reproducing a high-definition image, the volume average particle size is 5 to 1
It is desirable to use 0 μm toner.

The above toner can be used as a one-component developer or a two-component developer.

When used as a two-component developer, the above-mentioned toner and a known carrier may be mixed and used.

Next, the present invention will be described in more detail with reference to specific experimental examples.

(Production of Positively Chargeable Photoreceptor 1) JP-A-61-161
No. 25154, a photoconductor in which an a-Si photoconductive layer and an a-SiC surface protective layer were sequentially laminated on a conductive substrate was formed under the following manufacturing conditions using a known glow discharge decomposition apparatus.

Conditions for forming a-Si photoconductive layer: source gas (gas flow rate): H ₂ (486.5 scc)
m), SiH ₄ (90 sccm), B ₂ H ₆ (22.5s
ccm), O ₂ (1 sccm) ・ Pressure: 1.0 Torr ・ Frequency: 13.56 MHz ・ Power: 250 W ・ Substrate temperature: 240 ° C ・ Discharge time: 6 hours a-SiC surface protective layer (carbon-based high hardness coating layer) Formation conditions: -Source gas (gas flow rate): H ₂ (486.5 scc)
m), SiH ₄ (90 sccm), B ₂ H ₆ (90 sccc)
m), C ₂ H ₄ (270 sccm) ・ Pressure: 1.0 Torr ・ Frequency: 13.56 MHz ・ Power: 250 W ・ Substrate temperature: 240 ° C ・ Discharge time: 2 minutes In the above photoconductor, the film thickness is a-Si light About 20 conductive layers
μm, the thickness of the a-SiC surface protective layer was about 0.1 μm, and the Vickers hardness of the surface protective layer was 3000. Also,
The carbon content of the a-SiC surface protective layer is about 75 atomi.
It was c%.

(Production of Negatively Chargeable Photoreceptor 2) A photoreceptor was prepared by sequentially laminating an organic charge generating layer, an organic charge transporting layer, and a surface protective layer composed of an amorphous carbon film on a conductive substrate.

The organic charge generating layer and the organic charge transporting layer were obtained by sequentially applying a coating solution under the following conditions on a conductive substrate by a dipping method.

Organic charge generation layer (organic photosensitive layer) ・ 0.45 parts by weight of an azo compound represented by the following structural formula

[0054]

[Chemical 1]

Polyester resin (Byron 200: manufactured by Toyobo Co., Ltd.) 0.45 parts by weight Cyclohexanone 50 parts by weight Organic charge transport layer (organic photosensitive layer) 10 parts by weight of styryl compound represented by the following structural formula

[0056]

[Chemical 2]

Polycarbonate resin (Panlite K-
1300: Teijin Kasei Co., Ltd.) 7 parts by weight / 1,4-dioxane 40 parts by weight The organic charge generation layer had a thickness of about 0.3 μm, and the organic charge transport layer had a thickness of about 20 μm.

A surface protective layer for an amorphous carbon film is disclosed in JP-A-63-9.
7962 was formed on the organic charge transport layer using the already known glow discharge decomposition apparatus under the following manufacturing conditions.

Amorphous carbon film (carbon-based high hardness coating layer) -Source gas (gas flow rate): H ₂ (300 sccm), butadiene (15 sccm) -Pressure: 1.0 Torr-Frequency: 100 KHz-Power: 150 W-Substrate temperature : 50 ° C. Discharge time: 3 minutes The amorphous carbon film had a thickness of 0.11 μm and Vickers hardness of 1000. The carbon content in the amorphous carbon film was about 48 atomic%.

(Production of Carrier) The following materials were thoroughly mixed, melt-mixed with a twin-screw extrusion kneader, and then cooled.

100 parts by weight of polyester resin (Mn: 5000, Mw: 115000, Tg: 67 ° C., Tm: 123 ° C.) 500 parts by weight of ferrite fine particles (MFP-2: manufactured by TDK Corporation) 3 parts by weight of silica fine particles (Aerosil # 200: manufactured by Nippon Aerosil Co., Ltd.) The cooled product was roughly pulverized, then finely pulverized by a jet mill, and further classified by using an air classifier. The obtained carrier has a volume average particle diameter of 60 μm and an electric resistance value of 5.8 × 10 ¹³ Ω.
It was cm.

(Production of Positively Chargeable Toner) The materials shown below were thoroughly mixed, melt-mixed in a twin-screw extrusion kneader, and then cooled.

Styrene-acrylic copolymer resin 100 parts by weight (Mn: 5400, Mw: 156000, Tg: 60 ° C., Tm: 120 ° C.) Colorant: Carbon black 10 parts by weight (Raven 1250: Columbia Carbon Co., Ltd.)・ Anti-offset agent: 3 parts by weight of wax (Viscor 550P: manufactured by Sanyo Chemical Industry Co., Ltd.) ・ Charge control agent: 3 parts by weight of quaternary ammonium salt (P-51: manufactured by Orient Chemical Industry Co., Ltd.) , Finely pulverized with a jet mill and further classified with a wind classifier to obtain a volume average particle size of 9.5μ
m toner particles A were obtained.

(Production of Negatively Chargeable Toner) The following materials were thoroughly mixed, melt-mixed in a twin-screw extrusion kneader and then cooled.

100 parts by weight of styrene-acrylic copolymer resin (Mn: 5400, Mw: 156000, Tg: 60 ° C., Tm: 120 ° C.) ・ Colorant: carbon black 10 parts by weight (Raven 1250: Columbia Carbon Co., Ltd.)・ Anti-offset agent: Wax 3 parts by weight (Viscor 550P: manufactured by Sanyo Kasei Co., Ltd.) ・ Charge control agent: Chromium complex salt type azo dye 3 parts by weight (S-34: manufactured by Orient Chemical Industry Co., Ltd.) , Finely pulverized with a jet mill and further classified with a wind classifier to obtain a volume average particle size of 11.0.
Toner particles B of μm were obtained.

(Example 1) For 100 parts by weight of the toner particles B, 1.5 parts by weight of ferrite fine particles (volume average particle diameter of primary particles: 0.3 μm) as magnetic fine particles were added to a Henschel mixer (Mitsui Miike Kako Co., Ltd.). 3000 rp)
m for 5 minutes to immobilize on the surface of the toner particles.
Furthermore, hydrophobic silica (R972: volume average particle size 0.0
16 μm: manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by weight was added, and the mixture was treated at 1000 rpm for 1.5 minutes to obtain a toner to which silica was externally added. The volume average particle diameter of the obtained toner was 11.2 μm.

The toner and the carrier were mixed at a mixing ratio of 5:
The developer mixed in 95 was stored in a developing device of a copying machine EP8600 (manufactured by Minolta Camera Co., Ltd.) modified so that the photoconductor 1 could be used, and a copy durability test of about 600,000 sheets was performed. . Specifically, after copying the test chart for every 200,000 sheets at room temperature, after printing 10,000 sheets in an environment of a temperature of 30 ° C. and a humidity of 85%, the image flow of the obtained copied image and The fog on the white background was evaluated.

The evaluation criteria for image deletion are as follows.

O: No image deletion is observed.

Δ: Some bleeding is recognized at the end of the character.

X: The entire character flows.

XX: Characters cannot be identified.

If the evaluation is Δ or above, there is no problem in practical use. The evaluation results are as shown in Table 1.

The evaluation criteria for white background fog are as follows.

B: No fog is observed.

Δ: Some fog is recognized, but there is no problem in practical use (ID of white background is less than 0.15) ×: ID of white background exceeds 0.15 due to fog.

XX: The white background ID is 0.2 due to fogging
It exceeds 0.

If the evaluation is Δ or above, there is no problem in practical use. The evaluation results are as shown in Table 1.

Example 2 2.0 parts by weight of iron powder fine particles (volume average particle diameter of primary particles: 0.3 μm) as magnetic fine particles were added to 100 parts by weight of the toner particles A described above in a Henschel mixer (Mitsui Mitsuike). 3500 rpm at 3500 rpm
The toner particles were treated for a minute, and then fixed on the surface of the toner particles. Furthermore, alumina fine particles (C604: volume average particle size 0.02
μm: manufactured by Nippon Aerosil Co., Ltd.)
The toner was treated at 000 rpm for 1.5 minutes to obtain a toner to which alumina was externally added. The volume average particle diameter of the obtained toner was 9.8 μm.

This toner and the carrier are mixed at a mixing ratio of 5:
The developer mixed in 95 is stored in the developing device of a copying machine EP8600 (manufactured by Minolta Camera Co., Ltd.) modified so that the photoreceptor 2 can be used, and a copy durability test is conducted in the same manner as in Example 1. It was The experimental results are as shown in Table 1.

Example 3 2.0 parts by weight of ferrite fine particles (volume average particle diameter of primary particles: 0.3 μm) were used as magnetic fine particles with respect to 100 parts by weight of the above toner particles B, and externally added fine particles were used. A toner was obtained in the same manner as in Example 1 except that 0.3 part by weight of alumina fine particles (C604: volume average particle diameter 0.02 μm: manufactured by Nippon Aerosil Co., Ltd.) was used. The volume average particle diameter of the obtained toner was 11.2 μm. A copy printing durability test was conducted on this toner in the same manner as in Example 1. The experimental results are as shown in Table 1.

Example 4 3.0 parts by weight of ferrite fine particles (volume average particle diameter of primary particles 0.3 μm) as magnetic fine particles were used with respect to 100 parts by weight of the toner particles A, and externally added fine particles were used. Hydrophobic silica fine particles (R972:
Volume average particle diameter 0.016 μm: manufactured by Nippon Aerosil Co., Ltd.)
A toner was obtained in the same manner as in Example 2 except that 0.1 part by weight was used.

The volume average particle diameter of the obtained toner is 9.7 μm.
It was m. A copy durability test was conducted on this toner in the same manner as in Example 2. The experimental results are as shown in Table 1.

Example 5 With respect to 100 parts by weight of the toner particles A, 2.0 parts by weight of magnetite particles (volume average particle diameter of primary particles: 0.15 μm) were used as magnetic particles, and externally added particles were used. Hydrophobic silica fine particles (R9
74: volume average particle diameter 0.012 μm: manufactured by Nippon Aerosil Co., Ltd.) A toner was obtained in the same manner as in Example 2 except that 0.1 part by weight was used. The volume average particle diameter of the obtained toner is 9.
It was 7 μm. A copy durability test was conducted on this toner in the same manner as in Example 2. The experimental results are as shown in Table 1.

Example 6 With respect to 100 parts by weight of the toner particles B, 3.0 parts by weight of magnetite particles (volume average particle diameter of primary particles: 0.15 μm) were used as magnetic particles, and externally added particles were used. Hydrophobic silica fine particles (R9
74: volume average particle diameter 0.012 μm: manufactured by Nippon Aerosil Co., Ltd.) A toner was obtained in the same manner as in Example 1 except that 0.3 part by weight was used. The volume average particle size of the obtained toner is 1
It was 1.2 μm. A copy printing durability test was conducted on this toner in the same manner as in Example 1. The experimental results are as shown in Table 1.

Example 7 3.0 parts by weight of ferrite fine particles (volume average particle diameter of primary particles: 0.3 μm) as magnetic fine particles were used with respect to 100 parts by weight of the above toner particles B, and externally added fine particles were used. Hydrophobic titanium dioxide fine particles (MT
A toner was obtained in the same manner as in Example 1 except that 0.3 part by weight of -400BS: volume average particle diameter 0.04 μm: manufactured by Teika Co., Ltd. was used. The volume average particle size of the obtained toner is 1
It was 1.1 μm. A copy printing durability test was conducted on this toner in the same manner as in Example 1. The experimental results are as shown in Table 1.

(Example 8) 5.0 parts by weight of magnetite particles (volume average particle diameter of primary particles 0.15 μm) were used as magnetic particles with respect to 100 parts by weight of the above toner particles A, and externally added particles were used. Hydrophobic silica fine particles (R9
72: volume average particle diameter 0.016 μm: manufactured by Nippon Aerosil Co., Ltd.) A toner was obtained in the same manner as in Example 2 except that 0.1 part by weight was used. The volume average particle diameter of the obtained toner is 9.
It was 8 μm. A copy durability test was conducted on this toner in the same manner as in Example 2. The experimental results are as shown in Table 1.

Example 9 7.0 parts by weight of ferrite fine particles (volume average particle diameter of primary particles: 0.3 μm) as magnetic fine particles were used with respect to 100 parts by weight of the above toner particles B, and externally added fine particles were used. Hydrophobic silica fine particles (R972:
Volume average particle diameter 0.016 μm: manufactured by Nippon Aerosil Co., Ltd.)
A toner was obtained in the same manner as in Example 1 except that 0.3 part by weight was used.

The volume average particle diameter of the obtained toner is 11.2.
was μm. A copy printing durability test was conducted on this toner in the same manner as in Example 1. The experimental results are shown in Table 1.

(Comparative Example 1) A toner was obtained in the same manner as in Example 1 except that the magnetic fine particles were not fixed on the surface of the toner particles. The obtained toner has a volume average particle diameter of 11.0 μ.
It was m. A copy durability test was conducted on this toner in the same manner as in Example 1. The experimental results are as shown in Table 1.

(Comparative Example 2) A toner was obtained in the same manner as in Comparative Example 1 except that the amount of silica fine particles added externally was 0.3 part by weight. The volume average particle diameter of the obtained toner is 11.2 μ.
It was m. A copy durability test was conducted on this toner in the same manner as in Example 1. The experimental results are as shown in Table 1. However, after 400,000 sheets, the image deletion occurred and the fog became very bad, so the printing durability was finished.

Comparative Example 3 Same as Comparative Example 1 except that 0.1 part by weight of silica fine particles and 2.0 parts by weight of ferrite fine particles (volume average particle diameter of primary particles: 0.3 μm) are used as externally added fine particles. To obtain a toner. The volume average particle diameter of the obtained toner was 11.3 μm. A copy durability test was conducted on this toner in the same manner as in Example 1. The experimental results are as shown in Table 1.

(Comparative Example 4) A toner was obtained in the same manner as in Example 4 except that the fine particles were not externally added. The volume average particle diameter of the obtained toner was 9.7 μm. A copy printing durability test was conducted on this toner in the same manner as in Example 2. The experimental results are as shown in Table 1.

[0094]

[Table 1]

[0095]

As described above, according to the present invention, even when an image is formed by repeatedly carrying out printing using an image carrier having a carbon-based high hardness coating layer as a surface layer, the image is formed after printing. It is possible to obtain an excellent image in which no flow or fog in the white background occurs.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus for carrying out an image forming method of the present invention.

[Explanation of symbols]

1: photoconductor drum, 2: corona charger, 3: exposure light,
4: developing device, 5: transfer paper, 6: transfer charger,
7: Separation Charger, 8: Cleaning Device, 9: Main Eraser, 10: Fixing Device

Front page continuation (51) Int.Cl. ⁷ identification code FI G03G 15/08 507 G03G 15/08 507L (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 5/00-5/147 G03G 9/08-9/113 G03G 13/08-13/095 G03G 15/08-15/095

Claims (3)

(57) [Claims] 1. A toner obtained by immobilizing magnetic fine particles on the surface of toner particles and externally adding post-treated fine particles onto an image carrier having a carbon-based high hardness coating layer as a surface layer. An image forming method for developing a formed electrostatic latent image. 2. The addition amount of the magnetic fine particles is 1 to 10 wt% with respect to the toner particles, and the addition amount of the post-treatment fine particles is 0.05 to 5 wt% with respect to the toner particles. 1. The image forming method described in 1. 3. The image forming method according to claim 1, wherein the average particle diameter of the primary particles of the magnetic fine particles is 0.01 to 2 μm.