JP2835966B2 - Developing device and image forming method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention is used in the field of technology for developing an electrostatic latent image with a developer, and in particular, a developing device that performs development by restraining the developer with a magnetic force. And an image forming apparatus using the developing device.

2. Description of the Related Art Conventionally, for example, a developing device that visualizes a latent image formed on the surface of a photosensitive drum as an electrostatic latent image carrier with a magnetic toner as a one-component system has been developed. Due to friction and friction between the sleeve as a developer carrier and the magnetic toner particles, a charge having a polarity opposite to the electrostatic image charge formed on the photosensitive drum is applied to the magnetic toner particles, and the magnetic toner is applied very thinly on the sleeve. Then, the toner is conveyed to a developing area formed by the photosensitive drum and the sleeve, and in the developing area, the magnetic toner flies under the action of a magnetic field from a magnet fixed in the sleeve to visualize the electrostatic latent image on the photosensitive drum. Things are known.

[Problems to be Solved by the Invention] However, in each of the developing devices as described above, a relatively thin uniform toner layer must be formed on the sleeve. However, environmental conditions, toner physical properties, and surface conditions of the sleeve are required. In some cases, a uniform toner layer cannot be obtained, and unevenness often occurs, particularly in a low humidity environment.

Also, as the developer is repeatedly rubbed against the sleeve as the copying is repeated, additives for improving the fluidity of the toner and non-developable substances such as a carrier in the two-component toner are deposited on the sleeve, or the developer is developed. The surface condition of the sleeve changes because the binder resin in the developer forms a film on the sleeve, destabilizing the developability of the developer, or the transport of the developer to the electrostatic latent image surface is unstable There was a problem of becoming.

In order to prevent such a change in the surface state of the sleeve, for example, a film containing an inorganic high-molecular-weight fluorocarbon is formed (Japanese Patent Application Laid-Open No. 57-66443). What forms a good resin (JP-A-58-1783)
No. 80), forming a coating containing at least one selected from an organic silicon polymer, an aliphatic fluorine-containing compound, a styrene resin, and a polyphenylene oxide and a metal complex having a 2- to 6-dentate ligand. In particular, there have been proposed those which prevent a change in the surface state by coating a material having a particularly high releasability on the surface of the sleeve, such as the one described in JP-A-57-76558.

However, a coated sleeve in which a synthetic resin or the like is coated on the surface of the sleeve is clearly softer than a conventionally used aluminum or SUS sleeve. Therefore, the developer is pressed during the repetitive development operation, and this is particularly remarkable in the case of a magnetic developer containing a magnetic material. There is a problem that the performance inherent in the coat sleeve is liable to be deteriorated due to sticking or a part of the developer adhering.

An object of the present invention is to solve the above-described problems, to suppress uneven polishing and scratching on the surface of the developer carrying member, and to suppress film formation of a binder resin in the developer accompanying the damage, and to reduce the amount of the developer carrying member. An object of the present invention is to provide a developing device which easily deteriorates in performance and has good developing characteristics, and an image forming method using the developing device.

[Means and Actions for Solving the Problems] The present invention achieves the above object by the following constitutions.

The present invention has a magnet inside, for contacting a magnetic developer in a developer accommodating chamber, carrying the magnetic developer on a surface thereof, and transporting the developer to a developing area formed between the electrostatic latent image carrier, A developing device having a developer carrier having a coating layer containing a polymer material and conductive fine particles formed on the surface thereof, wherein the developing device has an AC bias applied to the developer carrier during development. The coating layer contains graphite particles as conductive fine particles and phenol resin as a polymer material, and the magnetic developer has a A developing device comprising: a magnetic toner containing 70% by weight (based on the weight of a magnetic developer) of magnetic fine particles and a binder resin; and a fine powder treated with silicone oil or silicone varnish. .

Further, the present invention has a magnet inside for contacting the magnetic developer in the developer accommodating chamber, carrying the magnetic developer on the surface, and transporting the magnetic developer to a developing area formed between the developer and the electrostatic latent image carrier. An image forming method using a developing device having a developer carrier having a coating layer containing a polymer material and conductive fine particles formed on the surface thereof, wherein the coating layer comprises graphite particles as conductive fine particles. A phenol resin is contained as a polymer material. The magnetic developer is a magnetic toner containing 10 to 70% by weight (based on the weight of the magnetic developer) of magnetic fine particles and a binder resin, and silicone oil or silicone varnish. And a fine powder that has been processed. The electrostatic latent image is applied to the electrostatic latent image carrier, and the electrostatic latent image is carried on the developer carrier while a developing bias having an AC bias is applied to the developer carrier. The magnetic current being The present invention relates to an image forming method characterized by developing with an image agent.

Hereinafter, the developing device of the present invention will be described with reference to the accompanying drawings.

 FIG. 1 is a sectional view of an example of the developing device of the present invention.

Reference numeral 1 in the figure denotes a photosensitive drum that carries an electrostatic latent image and rotates in the direction of arrow A as an electrostatic latent image carrier, and may have or may not have an insulating layer on the surface. Of course, not only the drum shape but also a sheet shape and a belt shape are possible. Reference numeral 2 denotes a sleeve as a developer carrier which carries a magnetic developer 5 on its surface and rotates in the direction of arrow B. Inside the sleeve 2, the multipolar permanent magnet 3 is fixed so as not to rotate. On the surface of the sleeve 2, a coating layer 10 containing conductive fine particles, which will be described later, has a thickness of about 0.5.
It is formed to a thickness of μm to 30 μm. Reference numeral 4 denotes a developer storage chamber for storing the magnetic developer 5 and bringing the magnetic developer 5 into contact with the surface of the sleeve 2. Reference numeral 6 denotes a doctor blade as a member for regulating the layer of the magnetic developer 5 on the surface of the sleeve 2 carried in the developer accommodating chamber 4 to a predetermined thickness, and a gap between the surface of the sleeve 2 and the doctor plate 6 is formed. About 50μm
It is arranged so as to be up to 500 μm.

When the developing device configured as described above is started and the sleeve 2 rotates in the direction of arrow B, the magnetic developer 5 in the developer storage chamber 4 or the contact friction between the surface of the sleeve 2 and the magnetic developer 5 causes An electric charge having a polarity opposite to that of the electrostatic latent image on the photosensitive drum 1 is given to the magnetic developer 5 and applied to the surface of the sleeve 2. The magnetic developer layer applied to the sleeve surface further includes one magnetic pole (S in the figure) of the multi-pole permanent magnet 3.
(Pole) is regulated so as to be a uniform and thin layer (layer thickness is about 30 μm to 300 μm) by a doctor blade 6 disposed opposite to the position, and is conveyed to a developing area formed by the photosensitive drum 1 and the sleeve 2. Is done.

In the developing area, the sleeve 2 and the photosensitive drum 1
The magnetic developer 5 on the sleeve 2 may be caused to fly in the direction of the photosensitive drum by applying a developing bias having an AC bias to the surface.

Here, the coating layer 10 formed on the sleeve surface will be described.

In the present invention, the coating layer 10 is formed of a polymer material for forming a coating layer containing conductive fine particles. Examples of the conductive fine particles include carbon fine particles and crystalline graphite particles. In the present invention, it is sufficient that the conductive fine particles include graphite particles.

The crystalline graphite used in the present invention is roughly classified into natural graphite and artificial graphite. Artificial graphite is
Pitch coke is solidified with a tar pitch or the like, fired once at about 1200 ° C., placed in a graphitization furnace, and treated at a high temperature of about 2300 ° C., whereby carbon crystals grow and change into graphite. Natural graphite is completely graphitized by natural geothermal heat and underground high pressure for a long time, and is produced from underground. Since these graphites have various excellent properties, they have wide industrial applications. Graphite is a dark gray or black glossy, very soft, lubricating crystalline mineral that is used for pencils and other materials.It has heat resistance and chemical stability, so it can be used as a powder in lubricants, fire resistance, electrical materials, etc. It is used in the form of solids and paints. The crystal structure includes hexagonal and other rhombohedral, and has a complete layer structure. Regarding electrical properties, free electrons exist between carbon and carbon bonds, and are good conductors of electricity. The graphite used in the present invention may be natural or artificial.

Further, the graphite particles used in the present invention preferably have a particle size of 0.5 μm to 10 μm.

As the film-forming polymer material, a phenol resin having excellent mechanical properties is used.

 Next, the magnetic developer according to the present invention will be described.

The developer of the present invention contains fine powder treated with silicone oil or silicone varnish, and the form is preferably such that the fine powder is attached to the particle surface of the magnetic toner.

Since the magnetic developer according to the present invention has the above-described configuration, the magnetic developer is pressed against even if repeated developing operations are performed, and the surface of the developer carrier is scratched or the magnetic developer adheres. This makes it possible to make full use of the performance of the original coat sleeve. That is, the magnetic developer according to the present invention is a magnetic developer that matches the image forming apparatus according to the present invention very well and can make full use of the image forming apparatus. By using the forming apparatus, an image forming method capable of providing a good image has been established.

The inventors of the present invention have known that fine particles present on the surface of the magnetic toner particles serve as a lubricant between the magnetic developer and the developer carrier. It is presumed that the treatment with varnish may reduce the impact of the contact between the fine particles and the developer carrying member.

The particle size of the fine powder used in the present invention is 0.001 to 2 μm
And particularly preferably 0.005 to 0.2 μm. The material of the fine powder used in the present invention is preferably an inorganic compound. For example, silicic acid, alumina, titanium oxide, etc.
Group 3 and group 4 metal oxides are preferred.

Particularly, fine silica powder is preferable. As the fine silica powder, a so-called dry method produced by vapor phase oxidation of a silicon halide compound or a dry silica called fumed silica, and a so-called wet method produced from water glass or the like both silica can be used, but less silanol groups on the inner surface and fine silica powder, and Na ₂ O, who dry silica without producing residue of SO ₃ ^2-like.

In the case of fumed silica, for example, in the manufacturing process, it is also possible to obtain a composite fine powder of silica and other metal oxides by using another metal halide such as aluminum chloride or titanium chloride together with a silicon halide, It also includes that.

In the silicone oil treatment of the fine powder used in the present invention, by coating the surface of the fine powder with the silicone oil, the silanol groups can be completely covered and concealed, and the moisture resistance is dramatically improved.

The silicone oil or silicone varnish solids used in the present invention is generally represented by the following formula, Examples thereof include dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil. The silicone oil preferably has a viscosity at 25 ° C. of about 50 to 10
A 00 centistoke is used. Silicone oil having a molecular weight that is too low may generate volatile components due to heat treatment or the like, and if the molecular weight is too high, the viscosity becomes too high, making the processing operation difficult.

Known methods are used for the method of silicone oil treatment.For example, fine powder and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or a method of spraying silicone oil on the base fine powder. good. Alternatively, the varnish may be formed by mixing with a base fine powder and then removing the solvent.

It is more preferable that the fine powder used in the present invention is first treated with a silane coupling agent, and then treated with a silicone oil or silicone varnish.

In general, when only silicone oil treatment is used, the amount of silicone oil to cover the surface of the fine powder is large, aggregates of the fine powder are easily formed during processing, and when applied to a magnetic developer, the fluidity of the magnetic developer becomes poor. Therefore, it is necessary to pay close attention to the processing steps of the silicone oil. Therefore, in order to remove the agglomerates of the fine powder while maintaining good moisture resistance, it is better to treat the fine powder with a silane coupling agent and then treat it with silicone oil to achieve a more effective treatment of silicone oil. is there.

The silane coupling agent used in the present invention has a general formula For example, typically, dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxysilane, γ-methacryloxypropyl Examples include trimethoxysilane, vinyltriacetoxysilane, divinylchlorosilane, and dimethylvinylchlorosilane.

The silane coupling agent treatment of the fine powder is performed by a dry process in which the vaporized silane coupling agent is reacted with a cloud of the fine powder by stirring or the like, or the fine powder is dispersed in a solvent and the silane coupling agent is dropped. The reaction can be carried out by a generally known method such as a wet method for reaction.

Silane coupling agent, 100 parts by weight of fine powder,
The treatment is preferably performed at 1 to 50 parts by weight, more preferably 5 to 40 parts by weight.

The treatment amount of the silicone oil or silicone varnish solids in the present invention is preferably 1 to 35 parts by weight, more preferably 2 to 30 parts by weight, based on 100 parts by weight of the fine powder. If the treatment amount is too small, the same result as in the silane coupling agent treatment alone is obtained, and the moisture resistance is not improved, and the fine powder absorbs moisture under high humidity, and a high-quality copy image cannot be obtained. On the other hand, if the processing amount of the silicone oil is too large, the above-mentioned fine powder aggregates are likely to be formed, or free silicone oil is formed, so that when applied to a magnetic developer, the flowability can be improved. There are drawbacks such as inability to do so.

The amount of the processed fine powder to be applied to the magnetic developer is 0.01 to 20 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the magnetic toner.

Examples of the binder resin of the magnetic toner according to the present invention include a homopolymer of styrene such as polystyrene and polyvinyltoluene and a substituted product thereof; a styrene-propylene copolymer, a styrene-vinyltoluene copolymer, and a styrene-vinylnaphthalene copolymer. Copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-meta Butyl acrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer Styrene-based copolymers such as polymers, styrene-isoprene copolymers, styrene-maleic acid copolymers, styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, Polyvinyl Butyral, polyacrylic acid resin, rosin, modified rosin, terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, paraffin wax, and carnauba wax may be used alone or in combination.

Further, as a coloring material which can be further added to the magnetic developer according to the present invention, conventionally known carbon black, copper phthalocyanine, iron black and the like can be used.

As the magnetic fine particles contained in the magnetic toner according to the present invention, a substance that is magnetized when placed in a magnetic field is used,
Powders of ferromagnetic metals such as iron, cobalt and nickel, or alloys and compounds such as magnetite, γ-Fe ₂ O ₃ and ferrite can be used.

These magnetic fine particles preferably have a BET specific surface area of 1 to ²⁰ m ² / g, particularly 2.5 to 12 m ² / g, and more preferably a magnetic powder having a Mohs hardness of 5 to 7 by a nitrogen adsorption method. The content of the magnetic powder is preferably from 10 to 70% by weight based on the weight of the magnetic developer.

The magnetic toner of the present invention may contain a charge control agent, if necessary, and a charge control agent such as a metal complex salt of a monoazo dye, a metal complex salt of salicylic acid, alkylsalicylic acid, dialkylsalicylic acid or naphthoic acid is used. Can be

The magnetic developer of the present invention may further contain other additives such as a lubricant such as Teflon and zinc stearate, or a fixing aid (for example, low-molecular-weight polyethylene, etc.) or a conductivity-imparting agent, as long as it does not substantially adversely affect the magnetic developer. A metal oxide such as tin oxide may be added as an agent.

In producing the magnetic toner of the present invention, a hot roll,
A method of obtaining a magnetic toner by mechanically pulverizing and classifying the constituent materials after kneading the constituent materials well by a heat kneader such as a kneader or an extruder, or dispersing the materials in a binder resin solution and then spray drying to obtain a magnetic material. Each method is applied, such as a method for obtaining a toner, or a polymerization method in which a predetermined material is mixed with a monomer to form a binder resin to form an emulsion and then polymerized to obtain a magnetic toner. it can.

[Examples] Specific examples will be described below, but the present invention is not limited by the following examples. In addition, the number of parts in each example is all parts by weight.

Example 1 After the above materials were uniformly mixed, kneaded, crushed and classified to obtain a magnetic toner having an average particle size of about 11 μm.

Next, Aerosil # 200 silicate fine powder with a specific surface area of 200 m ² / g
After 100 parts (manufactured by Nippon Aerosil Co., Ltd.) are treated with 20 parts of hexamethyldisilazane (HMDS), dimethylsilicone oil KF-96 100 cS (manufactured by Shin-Etsu Chemical) is diluted with a solvent and treated with 10 parts. After drying, heat treatment is performed at about 250 ° C., and hexamethyldisilazane treatment is performed, and then fine silica powder treated with dimethyl silicone oil is obtained. Obtained.

This magnetic developer and a commercially available laser beam printer LB
Modified P-SX (manufactured by Canon) and coated the surface of the developer carrier with a synthetic resin containing conductive graphite particles in phenol resin at a ratio of 1: 1 (coating layer thickness 8
μm), and the image output was evaluated.
Incidentally, the AC bias V _pp 1600 V for development bias, frequency 1800 Hz, the interval of the developer carrying member of the present invention was about 300 microns.

As a result, normal temperature and normal humidity (20 ° C, 60% RH), high temperature and high humidity (32.
Even in an environment of 5 ° C., 90% RH) and low temperature and low humidity (15 ° C., 10% RH), a good image having no environmental dependency and having no sleeve memory could be obtained.

Further, while image replenishment was performed on 5000 sheets while replenishing the magnetic toner, a satisfactory image without any problem was obtained. Further, no adhesion of the magnetic toner and no flaw were observed on the surface of the developer carrying member.

Example 2 The fine silica powder of Example 1 was converted to α-alumina (average particle size of 0.
020 μm, BET 100 cm ² / g), and the same processing was carried out to obtain a processed fine powder, and otherwise the same magnetic developer as in Example 1 was obtained, and an image was formed.

As a result, although the density slightly decreased compared to Example 1 after 3000 sheets, the density was at a level without any problem. Adhesion of the magnetic toner and generation of scratches were not observed on the surface of the developer carrying member after 5000 sheets of images were output.

Example 3 100 parts of silica silicate fine powder Aerosil # 130 (manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 130 m ² / g was mixed with dimethyl silicone oil K
The mixture was treated with a solution prepared by diluting 5 parts of F-96 with a solvent, dried, and then heat-treated at about 280 ° C. to obtain silica treated with dimethyl silicone oil, and a magnetic developer similar to that of Example 1 was obtained. Image evaluation.

As a result, good images were obtained as in Example 1.
In addition, although fine scratches were observed on the surface of the developer carrying member after 5,000 images were imaged, the level was not a problem without affecting the image.

Example 4 The same processing as in Example 3 was performed except that the processing amount of dimethyl silicone oil KF-96 was changed to 30 parts, and the same image formation evaluation was performed. It appeared as a spot-like defect, but at a practically acceptable level. Further, slight adhesion of the developer was observed on the surface of the developer carrier after image formation.

Comparative Example 1 The treating agent for the fine silica powder used in Example 1 was changed to only 20 parts of hexamethyldisilazane (HMDS), and a fine silica powder treated with hexamethyldisilazane was obtained. When the same magnetic developer as in Example 1 was obtained and image formation was evaluated, streak-like scratches were observed on the surface of the developer carrying member after 5,000 sheets of image formation. A white line appears to be based on the image.

[Effects of the Invention] As described above, the present invention relates to an image forming method using a developing device having a sleeve-shaped developer carrier having a magnet inside a coating layer containing conductive fine particles formed on the surface. By using the magnetic developer according to the present invention, it is possible to prevent the occurrence of scratches on the surface of the developer carrier, to provide a longer life, and to provide a good image without environmental dependency. it can.

[Brief description of the drawings]

 FIG. 1 is a diagram showing a sectional view of the developing device of the present invention. DESCRIPTION OF SYMBOLS 1 ... Electrostatic latent image carrier (photosensitive drum) 2 ... Developer carrier (sleeve) 3 ... Multipolar permanent magnet 4 ... Developer storage chamber 6 ... Doctor blade 10 ... Coating layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) The inventor Manabu Ohno 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-60-247669 (JP, A) JP-A-60 JP-A-45470 (JP, A) JP-A-63-195664 (JP, A) JP-A-59-45457 (JP, A) JP-A-63-139371 (JP, A) JP-B-52-36414 (JP, B2) )

Claims (2)

(57) [Claims] An inner magnet for contacting a magnetic developer in a developer accommodating chamber, carrying the magnetic developer on a surface thereof, and transporting the magnetic developer to a developing area formed between the developer and the electrostatic latent image carrier; And a developing device having a coating layer containing a polymer material and conductive fine particles formed on the surface thereof. The developing device includes a developing device having an AC bias to the developing device during development. An apparatus for developing an electrostatic latent image by applying a bias, wherein the coating layer contains graphite particles as conductive fine particles and a phenol resin as a polymer material. ~ 70% by weight (based on magnetic developer weight)
A magnetic toner containing the above magnetic fine particles and a binder resin, and a fine powder treated with silicone oil or silicone varnish. 2. A magnet for contacting a magnetic developer in a developer storage chamber, carrying the magnetic developer on a surface thereof, and transporting the developer to a developing region formed between the developer and the electrostatic latent image carrier. An image forming method using a developing device having a developer carrier having a coating layer containing a polymer material and conductive fine particles formed on the surface thereof, wherein the coating layer comprises graphite particles as conductive fine particles. Contains a phenolic resin as a polymer material, and the magnetic developer is 10 to 70% by weight (based on the weight of the magnetic developer)
A magnetic toner containing magnetic fine particles and a binder resin, and a fine powder treated with silicone oil or silicone varnish. Developing with the magnetic developer carried on the developer carrying member while applying a developing bias having an AC bias to the image forming apparatus.