JP3275227B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming method of a one-component developing system.

[0002]

2. Description of the Related Art Conventionally, many methods are known as electrophotography. In general, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means. The latent image is developed with a developer to form a visible image, and if necessary, the developer image is transferred to a transfer material such as paper, and then the developer image is fixed on the transfer material by heat, pressure, etc. and copied. Get things.

In recent years, devices using electrophotography have been increasing in number, such as printers and facsimile machines, in addition to conventional copying machines. Particularly in a printer or a facsimile, a developing device using a one-component developer is often used because it is necessary to reduce the size of a copying device.

[0004] Unlike the two-component system, the one-component system does not require carrier particles such as glass beads and iron powder, so that the developing device itself can be reduced in size and weight. Further, in the two-component developing method, since it is necessary to keep the toner concentration in the developer constant, a device for detecting the toner concentration and supplying a necessary amount of toner is required. Therefore, the developing device also becomes large and heavy here. In the one-component developing system, such a device is not required, so that the device can be made smaller and lighter, which is preferable.

On the other hand, with the recent increase in awareness of environmental protection / resource saving, it is necessary to reduce the amount of developer consumption (the amount of developer used to form one image) more than ever. It has been demanded.

The present inventor, while studying to achieve the above object, has found that more developer is developed in the line image area in the vertical direction of the image than in the solid image area.

It has been studied to reduce the amount of the developer excessively developed in the line image portion to an appropriate amount so as to reduce the consumption of the developer.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to fulfill the above-mentioned needs.

That is, an object of the present invention is to provide an image forming method which consumes less developer than conventional ones.

Another object of the present invention is to provide an image forming method capable of obtaining an image having a high image density and no fog.

[0011]

Means and operation for solving the problems] The present invention uses a developing device having a developer using a one-component developing method
An image forming method for developing an electrostatic latent image, and the peripheral speed relative to the photosensitive member of the developer carrying member in said developing device 105% or more, an electric field is applied, including an AC component to said developer carrying member
The peak of the AC component of the applied electric field
The magnitude of the two peaks (Vpp) is
4.0 kV / mm or more at the closest point to the light body
Ri, developer coated on said developer carrying member, in the volume particle size distribution, and containing less than 50% of particles having a particle size of at least 6.35Myuemu, developing in a developing device
Opening to the developer reservoir for the developer carrier in the developer container
The present invention relates to an image forming method having a width of 12 mm or less .

As described above, more developer is developed in the vertical direction of the image in the line image portion than in the solid image portion. The reason is considered as follows.

In the electrostatic latent image of the line image portion, unlike the solid image portion, the lines of electric force wrap around the line image portion from outside the line image portion. Therefore, the force for pressing the developer against the surface of the photoconductor is stronger in the line image area than in the solid image area.

In the one-component developing method, the developer is developed on the surface of the photoreceptor in a state where the developer particles are aggregated to some extent. It is considered that an excessive amount of the developer remains on the line image portion because the developer receives the strong electric field of the line image latent image portion and is pressed against the surface of the photoreceptor in the aggregated state.

The reason why the amount of the developer remaining in the line image portion is small and the consumption of the developer can be reduced by the image forming method of the present invention as compared with the conventional developer is considered as follows.

In the image forming method of the present invention, the developer carrier is at least 105% (preferably 1%) of the photosensitive member.
(20% or more), the developer aggregate has a speed difference with respect to the photoconductor surface. Due to the speed difference, a shear force acts on the aggregate of the developer on the surface of the photoreceptor, and a force for loosening the aggregate acts. If the peripheral speed of the developer carrier with respect to the photoconductor is less than 105%, the effect of loosening the aggregation of the developer is small, and the effect of reducing the consumption of the developer cannot be obtained.

Further, in the image forming method of the present invention,
6.3 in volume particle size distribution in developer used for development
5% or more is 50% or less (preferably 35% or less), and the developer having a small particle size and strong adhesion to the photoreceptor surface occupies more than half of the whole. Therefore, the shearing force caused by the speed difference acting between the photoreceptor surface and the developer aggregate becomes more effective, and the effect of loosening the aggregation appears more strongly.

When 6.35 μm or more in the volume particle size distribution of the developer coated on the developer carrier exceeds 50%, the ratio of the developer having a small adhesive force of the developer particles to the photoreceptor surface is large, The effect of loosening the agglomeration of the developer due to the peripheral speed difference between the developer carrier and the photoconductor is not sufficiently exhibited, and the effect of reducing the consumption of the developer cannot be obtained.

The developer is considered to be deagglomerated, so that a proper amount or more of the developer is returned to the developer carrier, and only a smaller amount of the developer remains on the photoreceptor. I have.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The developing step of the image forming method of the present invention will be described in detail.

The one-component developing method used in the image forming method of the present invention includes a method using a magnetic developer and a method using a non-magnetic developer.

First, a method using a magnetic developer will be described.

In FIG. 1, the substantially right half peripheral surface of the developer carrier 102 is always in contact with the developer reservoir in the developer container 106, and the developer near the surface of the developer carrier is charged with the developer. Is held by the magnetic force of the magnetism generating means 103 in the developer carrier and / or by the electrostatic force. The developer carrying member 102 is advice service as a thin layer T ₁ of the Components uniform thickness in the course of magnetic developer layer when driven rotation thereof the surface of the developer carrying member passes through the position of the doctor blade 104. The magnetic developer is charged mainly by contact between the surface of the developer carrier and the magnetic developer in a developer reservoir near the developer carrier. The thin layer of the magnetic developer on the developer carrier 102 is rotated by the rotation of the developer carrier. As a result, the photosensitive member 101 rotates toward the photosensitive member 101 and passes through the developing area A, which is the closest part between the photosensitive member 101 and the developer carrier 102. During this passage, the developer carrier 10
2 The magnetic developer in the thin layer of magnetic developer on the surface side
Flies between the photoconductor 101 surface of the development area A and the developer carrier 102 (gap α).
Reciprocate. The developer image T ₂ selectively shifts adhered to in accordance with the potential pattern of the latent image on the surface of the magnetic developer of the developer carrying member 102 side of the photosensitive member 101 surface are successively formed eventually.

After passing through the developing area A, the surface of the developer carrier on which the magnetic developer is selectively consumed is placed in the developer container 106.
Receiving a resupply of magnetic developer by re rotation in the developer reservoir, the magnetic thin developer layer T ₁ side of the developer carrying member 102 is transferred, repeatedly developing step is carried out to the developing area unit A.

The doctor blade used in the present invention comprises:
Any of a metal blade, a magnetic blade, or an elastic blade that abuts on the surface of the developer carrier with an elastic force can be used, but the metal blade is disposed at a fixed gap from the developer carrier.
In the present invention, a regulating method using a blade abutting on the surface of the developer carrying member is particularly preferable.

The volume particle size distribution of the developer coated on the developer carrier must be at least 6.35 μm but not more than 50%. However, the regulation method using a blade in contact with the surface of the developer carrier is more preferable. Is easy to realize.

As the elastic blade in contact with the surface of the developer carrier, a rubber elastic body such as silicone rubber, urethane rubber or NBR; a synthetic resin elastic body such as polyethylene terephthalate; and a metal elastic body such as stainless steel or steel can be used. Further, even a complex thereof can be used. Preferably, a rubber elastic body is good.

Further, the material of the elastic blade greatly affects the charging of the developer on the developer carrier. Therefore, an organic substance or an inorganic substance may be added to the elastic body, may be melt-mixed, or may be dispersed. For example, metal oxides, metal powders, ceramics, carbon allotropes, whiskers,
Examples include inorganic fibers, dyes, pigments, and surfactants. Furthermore,
For the purpose of controlling the chargeability of the developer, a material such as resin, rubber, metal oxide, or metal that is applied to a portion in contact with the developer carrier may be used for the purpose of controlling the charging property of the developer. good. When durability is required for the elastic body and the developer carrying member, it is preferable to bond a resin and a rubber to the metal elastic body so as to abut on the contact portion of the developer carrying member.

When the developer is negatively chargeable, it is preferable that the developer be easily charged to a positive polarity, such as urethane rubber, urethane resin, polyamide resin and nylon resin. When the developer is positively chargeable, it is preferable to use a material which is easily charged to a negative polarity, such as a silicone rubber, a silicone resin, a polyester resin, a fluorine-based resin, and a polyimide resin, in addition to urethane rubber and urethane resin.

In the case where the contact portion of the developer bearing member is a molded product such as a resin or rubber, silica, alumina, titania, tin oxide, zirconia, zinc oxide, etc. It is also preferable to include a metal oxide, carbon black, and a charge control agent generally used for a developer.

The base on the upper side of the elastic blade is fixed and held on the developer container side, and the lower side is bent in the forward or reverse direction of the developer carrying member against the elasticity of the blade for development. It is brought into contact with the surface of the agent carrier with moderate elastic pressure. 2 and 3 show examples of the image forming apparatus.

The contact pressure between the elastic blade and the developer carrying member is 0.98 N /
m (1 g / cm) or more, preferably 1.27 to 245 N
/ M (3-250 g / cm), more preferably 4.9-
118 N / m (5 to 120 g / cm) is effective. If the contact pressure is less than 0.98 N / m (1 g / cm), it becomes difficult to apply the developer uniformly, which causes fogging and scattering. The contact pressure is 245 N / m (250 g / c
If the value exceeds m), a large pressure is applied to the developer, and the deterioration of the developer is likely to occur, which is not preferable.

The gap α between the photosensitive member and the developer carrying member is preferably set to, for example, 50 to 500 μm.

The layer thickness of the developer layer on the developer carrier is preferably smaller than the gap α between the photoconductor and the developer carrier, but a part of the developer layer contacts the surface of the photoconductor. Such a form can also be used.

In the present invention, it is preferable that an electric field containing an AC component is applied between the developer carrier and the photosensitive member. Further, it is more preferable that the peak-to-peak electric field (Vpp) at the nearest part of the AC component between the developer carrier and the photoconductor is 4.0 kV / mm or more. The effect of the electric field containing an alternating current component between the developer carrier and the photoconductor further enhances the effect of the shearing force that loosens the aggregation of the developer that acts on the photoconductor surface. The frequency of the AC bias is 1.0 kHz to 5.0 kHz, preferably 1.5 kHz to 3.0 kHz. As the waveform of the AC bias, a waveform such as a rectangular wave, a sine wave, a sawtooth wave, and a triangular wave can be applied. In addition, asymmetrical AC biases having different times for applying the forward / reverse voltage can be used.

In the present invention, the developer carrier is made of metal,
Although materials such as ceramics are used, aluminum, SUS, and the like are preferable from the viewpoint of charging property to the developer. The developer carrier can be used as it is drawn or cut, but it can be polished, roughened in the circumferential or longitudinal direction, or blasted to control the developer transportability and triboelectricity. Processing and coating are performed. In the present invention, blast treatment may be performed, and shaped particles and irregular shaped particles are used as a blasting agent, and they may be used alone or in combination, and may be used as a blasting agent.

The developer carrier preferably has a coating layer containing conductive fine particles formed on the surface of the developer carrier.

As the conductive fine particles contained in the resin layer covering the surface of the developer carrier, conductive metal oxides such as carbon black, graphite, conductive zinc oxide and the like, and metal double oxides may be used alone or in combination. These are preferably used. Examples of the resin in which the conductive fine particles are dispersed include phenolic resins, epoxy resins, polyamide resins, polyester resins, polycarbonate resins,
Known resins such as polyolefin resin, silicone resin, fluorine resin, styrene resin, and acrylic resin are used. Particularly, a thermosetting or photocurable resin is preferable.

Next, an example of the case of performing non-magnetic one-component development using a non-magnetic developer will be described.

FIG. 4 shows an apparatus for developing an electrostatic image formed on a photosensitive member. Reference numeral 401 denotes a photoconductor, and a latent image is formed by an electrophotographic process unit or an electrostatic recording unit (not shown). Reference numeral 402 denotes a developer carrier, which is formed of a non-magnetic sleeve made of aluminum, stainless steel, or the like.

As the developer carrying member, a rough tube of aluminum or stainless steel may be used as it is, but preferably the surface is uniformly roughened by spraying glass beads or the like, mirror-finished, resin or the like. It is preferably coated, which is similar to that used in a magnetic one-component developing method.

The developer 406 is stored in a developer container 403, and is supplied onto a developer carrier by a supply roller 404. The supply roller is made of a foamed material such as polyurethane foam, and rotates in a forward or reverse direction at a relative speed other than 0 with respect to the developer carrier, and together with the supply of the developer, the development after development on the developer carrier is performed. The developer (undeveloped developer) is also stripped. The developer supplied onto the developer carrier is uniformly and thinly applied by the developer application blade 405.

The material of the blade, the contact means, the material of the developer carrier, the distance between the photosensitive member and the developer carrier, the bias applied to the developer carrier, and the like are the same as those of the magnetic one-component developing method. Follow.

In general, the particle size distribution of the original developer charged into the developer container and the particle size distribution of the developer coated on the developer carrier are greatly different. This phenomenon is thought to be caused by the action of electrostatic force and magnetic force on the sleeve surface, whereby particles of a certain particle size in the developer are selectively attracted to cause a selective coating. At this time, the particle size distribution of the developer coated on the developer carrier tends to be broad, and the ratio of 6.35 μm or more in the volume particle size distribution tends to increase as compared with the original developer.

As a preferred configuration of the developing device for suppressing this phenomenon in the present invention, it is preferable to make the portion of the developer carrying member 102 in contact with the developer reservoir on the substantially right half surface in FIG. 1 smaller. That is, the opening width in the developer reservoir is preferably 12 mm or less, more preferably 10 mm or less, and further preferably 8 mm or less. As a specific means, for example, an embodiment having a member 504 for partitioning a developer reservoir and a developer carrier as shown in FIG.

The reason that the above-mentioned phenomenon can be suppressed by adopting such a structure is that the chance of contact between the developer in the developer reservoir and the developer carrying member is reduced by reducing the opening width. I think that the selective coat of this can be suppressed.

As another structure, the developer carrier 1
The amount of the developer attracted by the magnetic force to the substantially right half surface of the developer carrier 102 by adjusting the magnetic force / position of the substantially right half surface of the magnetism generating means 103 built in the sensor 02 is reduced. preferable.

Next, the developer used in the image forming method of the present invention will be described in detail.

In the image forming method of the present invention, the volume particle size distribution of 6.35 μm or more in the developer coated on the developer carrier is 50% or less.

As described above, the particle size distribution of the developer coated on the developer carrying member is different from the particle size distribution of the original developer. The particle size distribution of the developer is also important.

The ratio of 6.35 μm or more in the volume particle size distribution of the original developer used in the present invention is 70% to 10%, preferably 60% to 10%, more preferably 50% to 10%.
It is preferable that If it exceeds 70%, 6.3 in the volume particle size distribution of the developer coated on the developer carrying member is obtained.
It is difficult to make 5 μm or more to 50% or less, and if it is less than 10%, it becomes difficult to obtain a sufficient image density.

In the image forming method of the present invention, it is preferable that the developer contains 1% by weight or more of inorganic fine powder. The inorganic fine powder contained in the developer exists between the developer particles and has a function of suppressing the cohesion between the developers, and the action of loosening the cohesion due to the shearing force on the photoreceptor surface works more effectively. Become like Preferably, the inorganic fine powder is contained by stirring and mixing with a developer using a mixer such as a Henschel mixer.

The inorganic fine powder used in the present invention includes:
Inorganic fine powders such as silicic acid fine powder, titanium oxide, and aluminum oxide are preferable, and silicic acid fine powder is particularly preferable. For example, as the fine silica powder, both a so-called dry method produced by vapor phase oxidation of a silicon halide or a dry silica called fumed silica, and a so-called wet silica produced from water glass or the like can be used. There are few silanol groups on the surface and inside the silica fine powder,
Further, dry silica having less production residue such as Na ₂ O, SO ₃ ^2- is more preferable. In the case of fumed silica, for example, aluminum chloride, titanium chloride, etc.
By using another metal halide compound together with a silicon halide compound, it is possible to obtain a composite fine powder of silica and another metal oxide, and these are included.

Further, a material whose surface has been previously rendered hydrophobic with an organic compound may be used. As such an organic treatment method, a method of treating with an organometallic compound such as a silane coupling agent that reacts or physically adsorbs with the inorganic derivative, a titanium coupling agent, or after treatment with a silane coupling agent, or A method of treating with a silane coupling agent and treating with an organosilicon compound such as silicone oil at the same time.

Examples of the silane coupling agent include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, and benzyldimethylchlorosilane. Silane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethyldiethoxysilane Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3
-Divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule, each of the terminal units having one hydroxyl group bonded to one silicon atom. Contained dimethylpolysiloxane.

Also, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, Butylaminopropyltrimethoxysilane, dioctylaminopropyldimethoxysilane, dibutylaminopropyldimethoxysilane,
Silane coupling agents such as dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamine, and trimethoxysilyl-γ-propylbenzylamine are also used alone or in combination. Preferred silane coupling agents include hexamethyldisilazane (H
MDS).

Particularly, in the image forming method of the present invention, a form in which a silicone oil is contained in a developer is preferable. Silicone oil assists the charging of the developer and makes the action of loosening the aggregation of the developer on the surface of the photoreceptor more effective.

Preferred silicone oils include 25
0.5-1000 centistokes at ℃
Preferably, those having 1 to 1000 centistokes are used, and for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil and the like are particularly preferred. As a method of the silicone oil treatment, for example, silica fine powder treated with a silane coupling agent and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or silicone fine powder serving as a base may be mixed with silicone fine powder. A method of spraying oil may be used. Alternatively, a method of dissolving or dispersing a silicone oil in an appropriate solvent, adding a silica fine powder, mixing and removing the solvent may be used.

It is also preferable that the silicone oil is contained by being internally added to the developer particles.

[0060] Inorganic fine powder used in the present invention is the specific surface area by nitrogen adsorption measured by BET method is 30 m ² / g or more, particularly in the range of 50 to 400 m ² / g give good results.

Examples of the binder resin used in the image forming method of the present invention include a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene and a substituted product thereof; a styrene-vinylnaphthalene copolymer, Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-maleic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid copolymer Styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer -Based copolymer; polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin , Xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin and the like can be used. Further, a crosslinked styrene resin is also a preferable binder resin.

Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and the like.
Such as dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. A monocarboxylic acid having a heavy bond or a substituted product thereof;
For example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate, and the like; and vinyl chloride;
Vinyl esters such as vinyl acetate, vinyl benzoate and the like, for example, ethylene olefins such as ethylene, propylene, butylene and the like; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone;
For example, vinyl monomers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; and the like, or a vinyl monomer such as vinyl monomers, may be used alone or in combination. Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene or the like; for example, ethylene glycol diacrylate, ethylene glycol Dimethacrylate,
Carboxylic esters having two double bonds such as 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinylether, divinylsulfide, divinylsulfone; and compounds having three or more vinyl groups; Can be used alone or as a mixture.

In the bulk polymerization method, a low molecular weight polymer can be obtained by increasing the termination reaction rate by polymerizing at a high temperature, but there is a problem that the reaction is difficult to control. In the solution polymerization method, a low molecular weight polymer can be easily obtained under mild conditions by utilizing the difference in chain transfer of radicals depending on the solvent, and by adjusting the amount of the initiator and the reaction temperature. It is preferable when a low molecular weight compound is obtained in the composition.

As a solvent used in the solution polymerization, xylene, toluene, cumene, cellosolve acetate, isopropyl alcohol, benzene and the like are used. In the case of a styrene monomer mixture, xylene, toluene or cumene is preferred. It is appropriately selected depending on the polymer to be polymerized.

The binder resin for the developer used for pressure fixing includes low molecular weight polyethylene, low molecular weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, higher fatty acid, and the like. Polyamide resin and polyester resin are mentioned. These are preferably used alone or as a mixture.

It is also preferable to include the following waxes in the developer from the viewpoint of improving the releasability from the fixing member at the time of fixing and improving the fixing property. Paraffin wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, carnauba wax and its derivatives, and the derivatives include oxides and block copolymers with vinyl monomers. , Graft-modified products.

In addition, alcohols, fatty acids, acid amides,
Esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, animal waxes, mineral waxes, petrolactam and the like can also be used.

Further, when the developer used in the image forming method of the present invention contains a magnetic material, the effect of the present invention is particularly remarkable.

As the magnetic substance to be contained in the developer, an alloy or compound powder containing a ferromagnetic element is preferable. For example, magnetite, maghemite, ferrite, etc.
Alloys and compounds of iron, cobalt, nickel, manganese, zinc, and the like, and other ferromagnetic alloys and the like, which are conventionally known as magnetic materials, can be given.

Also, on the surface or inside of the magnetic particles,
Materials containing compounds such as oxides, hydrated oxides, and hydroxides of metal ions such as Si, Al, and Mg can be used. Particularly, a magnetic material containing a compound of Si and Al is preferable. As the shape of the magnetic material, octahedron, hexahedron, sphere,
Needle-like, scale-like, etc. The BET specific surface area of the magnetic substance as measured by a nitrogen gas adsorption method is preferably 1 to 40 m ² / g, more preferably ² to 30 m ² / g. The average particle size of the magnetic material is 0.05-1 μm, preferably 0.1-0.
6 μm is preferred.

As the charge control agent, the following compounds may be added. For example, an organic metal complex and a chelate compound are effective, and examples thereof include a monoazo metal complex, an acetylacetone metal complex, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid-based metal complex. Other examples include aromatic hydroxycarboxylic acids, aromatic and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

In the production of the developer according to the present invention, the above-mentioned constituent materials are sufficiently mixed by a ball mill or other mixer, and then kneaded well using a hot kneader such as a hot roll kneader or an extruder. After cooling and solidifying the kneaded product, a method of obtaining a developer by mechanical pulverization and classification of the pulverized product is preferable. Another method is to obtain a developer by dispersing the constituent materials in a solution of the binder resin and then spray-drying; emulsifying and suspending the monomer to constitute the binder resin by mixing a predetermined material with the monomer. There is a production method by a polymerization method in which a liquid is formed and then polymerized to obtain a developer. Further, a microcapsule developer comprising a core agent and a shell agent may be used.

The particle size distribution of the developer coated on the developer carrier is measured as follows.

The developer coated on the developer carrier is
Rinse directly with water containing a small amount of surfactant and sample.

The particle size distribution of the sampled developer can be measured by various methods such as Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter Co., Ltd.).
-Interface (Nikkaki) and PC9 for outputting number distribution and volume distribution using type II (manufactured by Coulter)
801 personal computer (manufactured by NEC) is connected, and the electrolyte is 1% NaCl using primary sodium chloride.
Prepare an aqueous solution. For example, ISOTON R-II
(Manufactured by Coulter Scientific Japan) can be used. As a measuring method, the electrolytic aqueous solution 100 to 1
In 50 ml, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the volume and the number of the developer of 2 μm or more were measured using a 100 μm aperture as a rear aperture by the Coulter Counter TA-II. Was measured to calculate a volume distribution and a number distribution. Then, the ratio of 6.35 μm or more in the volume distribution according to the present invention was determined.

[0076]

EXAMPLES In the following formulations, parts are parts by mass.

Example 1 An image forming apparatus having the following configuration was used.

As a developer carrier, carbon black and graphite were coated on the surface of an aluminum cylinder (outer diameter 16 mm) previously blasted with amorphous abrasive grains in a ratio of 1: 9 parts in 10 parts of a phenol resin. One coated with a resin coating layer dispersed in a ratio was used. Further, the magnetic flux density of the developing pole is 75 mT (75 mT) inside the cylindrical sleeve.
0G) built-in 4-pole magnet.

A urethane rubber blade was used as a developer regulating member. As shown in FIG.
(20 g / cm).

As shown in FIG. 5, a partition plate is provided immediately behind the developer carrier in the developer container, and the distance B (opening width) from the tip to the developer carrier contact portion of the developer regulating member is 7 mm. It was set up to be.

An organic photoreceptor having a diameter of 30 mm was used as the photoreceptor, and the closest distance between the developer carrier and the photoreceptor was 30
It was set to 0 μm.

A roller charger was used as a primary charger, and a laser beam was used as an exposure means. A roller charger was used as the transfer charger.

A blade cleaning device was used as a cleaning device for removing the developer remaining on the photosensitive member in the transfer step, and a urethane rubber blade was used as the cleaning blade.

The potential of the latent image on the photosensitive member is -7
The voltage was set so as to be 00 V and the bright portion potential was -150 V.

The photosensitive member was rotated at 72 mm / s. The developer carrier was rotated at 108 mm / s (with respect to the photoconductor: 150%).

As a developing bias, DC voltage: -500 V, AC voltage: 1600 V (peak)
, A rectangular wave having an alternating frequency of 1800 Hz was applied.

On the other hand, the developer was obtained as follows.

• Styrene-n-butyl acrylate-monobutyl acrylate copolymer 100 parts • Magnetic iron oxide 100 parts • Low molecular weight polypropylene 3 parts • Monoazo iron complex 0.5 part After pre-mixing the above materials, Melt kneading was performed by a twin-screw kneading extruder set at 130 ° C. After cooling the kneaded material, the mixture was coarsely pulverized, finely pulverized by a pulverizer using a jet stream, and further classified using an air classifier to obtain a classified product having a volume distribution of 6.35 μm or more of 52%.

To 100 parts of the classified product, 1.5 parts of dry silica treated with dimethyl silicone oil was stirred and mixed with a Henschel mixer to obtain a developer 1.

The above-mentioned developer 1 was applied to the image forming apparatus, and image formation evaluation was performed in an environment of 23 ° C./65 RH%.
The developer consumption was evaluated by continuously printing a letter-size image composed of line character images at a printing rate of 4%.
The measurement was performed between 00 sheets and 1500 sheets.

At this time, 32% was 6.35 μm or more in the volume particle size distribution of the developer coated on the developer carrier.

The results are shown in Table 1.

Examples 2 to 4 and Comparative Example 1 Evaluation was made in the same manner as in Example 1 except that the peripheral speed of the developer carrying member of the image forming apparatus of Example 1 was as shown in Table 1.
Table 1 shows the results.

Example 5 and Comparative Example 2 Table 2 shows the distance B (opening width) from the tip of the partition plate of the image forming apparatus of Example 1 to the contact portion of the developer regulating member with the developer carrier. The evaluation was performed in the same manner as in Example 1 except that the evaluation was performed. Table 2 shows the results.

Examples 6 and 7 Evaluations were made in the same manner as in Example 1 except that the ratio of 6.35 μm or more in the volume distribution of the developer was as shown in Table 2. Table 2 shows the results.

Reference Examples, Embodiments 8 and 9 Same as Embodiment 1 except that the peak-to-peak magnitude of the AC bias applied to the developer carrier of the image forming apparatus of Embodiment 1 is as shown in Table 3. Was evaluated. Table 3 shows the results.

Examples 10 to 12 Evaluations were made in the same manner as in Example 1 except that the amount of dry silica treated with dimethyl silicone oil externally added to the classified products was as shown in Table 4. Table 4 shows the results.

[0098]

[Table 1]

[0099]

[Table 2]

[0100]

[Table 3]

[0101]

[Table 4]

[0102]

According to the present invention, the effect of loosening the aggregation of the developer due to the peripheral speed difference between the developer carrier and the photosensitive member can be obtained, and the consumption of the developer can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an image forming apparatus and a developing process used in a magnetic one-component developing method of the present invention.

FIG. 2 is a view schematically showing a developing device using an elastic blade used in the present invention.

FIG. 3 is a view schematically showing a developing device using an elastic blade used in the present invention.

FIG. 4 is a diagram schematically illustrating an image forming apparatus and a developing process used in the non-magnetic one-component developing method of the present invention.

FIG. 5 is a view schematically showing a developing device having a partition plate.

[Explanation of symbols]

Reference Signs List 101 photosensitive member (latent image holding member) 102 developer carrier (developing sleeve) 103 magnetism generating means 104 doctor blade 105 stirring member 106 developer container A developing area α gap between drum and sleeve T ₁ developer thin layer T ₂ developing Agent image S ₀ , S ₁ Bias applying unit 201, 301, 501 Photoconductor 202, 302, 502 Developer carrier 203, 303, 503 Doctor blade 401 Photoconductor 402 Developer carrier 403 Hopper 404 Supply roller 405 Developer application Blade 406 Developer 504 Partition plate B Opening width

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/08-15/095

Claims (6)

(57) [Claims] 1. A An image forming method for developing an electrostatic latent image using <br/> developing device having a developer using a one-component development system, the photosensitive member of the developer carrying member in the developing device Is not less than 105%, and an electric field containing an AC component is applied to the developer carrying member.
Of the AC component of the applied electric field.
Size (Vpp) between the developer carrier and the photoconductor
And a 4.0 kV / mm or higher at the closest portion, the developer coated on said developer carrying member, in the volume particle size distribution, the particles having a particle size of at least 6.35Myuemu 5
0% or less, and is contained in the developer carrier in the developer container in the developing device.
An image forming method, wherein an opening width to a developer reservoir is 12 mm or less . 2. The developer coated on the developer carrier contains 35% or less of particles having a particle size of 6.35 μm or more in a volume particle size distribution. 2. The image forming method according to 1., 3. The image forming method according to claim 1, wherein the peripheral speed of the developer carrying member relative to the photosensitive member is 120% or more. 4. As a doctor blade for regulating the layer thickness of the developer coat layer on the developer carrying member, according to claim 1, wherein the use restriction method according to abut the blade to the developer carrying member surface The image forming method according to any one of the above. 5. The image forming method according to any one of claims 1 to 4 developer is characterized by containing the inorganic fine powder 1.0 wt% or more. 6. The image forming method according to any one of claims 1 to 5 developer is characterized by containing the silicone oil.