JPH09185263A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make rising for electrifying a developer excellent and an electrification distribution sharp, to prolong a service life and to form an image of high density and quality, without irregularities in density and a development ghost, with a compact device by providing a developer carrier whose surface has a nickel layer and a toner chamber and attaining development under the condition that magnetic carriers exist only on the developer carrier. SOLUTION: The back of the developer carrier 3 is filled with toner 81 in the toner chamber. A latent image on a latent image carrier is developed with the developer 8, to form a toner image. However, at this time, a developer layer regulating member is adjusted to a proper interval, to carry the magnetic carriers on the developer carrier 3, together with the toner 81, so that almost all the magnetic carriers are carried on the developer carrier. As the developer carrier 3 used here, one having the nickel layer on the surface is used. The developer carrier 3 can be produced in a producing method for executing the extrusion molding of aluminium or an aluminium alloy and then, surface nickel plate working.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small size process having a step of forming a layer of a developer on a developer carrier having a small diameter, conveying the developer layer to a developing area, and developing a latent image on a latent image carrier having a small diameter. The present invention relates to an image forming method by an image forming apparatus.

[0002]

2. Description of the Related Art In recent years, the electrophotographic dry developing system has been used not only in electrostatic copying machines, but also in printers, facsimile machines, or multi-function machines having copying machines and printers and facsimile machines. In particular, as a recent trend, ecological measures such as stronger miniaturization and weight reduction, resource saving and recycling are required. Then, in order to cope with this, improvement of the image forming method and new development are being carried out. 2. Description of the Related Art Conventionally, as an electrophotographic dry development method, a method using a two-component developer made of a carrier and a method using a one-component developer not using a carrier have been known, and research and development have been actively conducted. The two-component developing method is the most widely used method, but a toner concentration control system to keep the toner concentration in the developer constant,
A mixing device for mixing the toner newly added to the developer and the developer is required, and it does not sufficiently satisfy the demands for downsizing and the like.

Therefore, as a developing system, there is an increasing demand for a one-component developing system which is characterized in that the developing device is small and lightweight and the toner density control is not troublesome. As the toner used in the one-component developing method, it has been conventionally known to use a magnetic toner containing a magnetic material and a non-magnetic toner not containing a magnetic material, but it is easy to control the conveyance of the toner, Magnetic toners are now widely used because of the low internal contamination of copying machines and printers.

On the other hand, with respect to copying machines and printers, efforts have been made to reduce the size and weight of each subsystem in order to reduce the size and weight. However, in the one-component development method, problems such as low developability due to the slow rise of charging and a wide charge distribution, background fog, and uneven density due to development ghost occur, and the above-mentioned ultra-compact This is an obstacle to establishing an image forming method. On the other hand, as a method of suppressing the above problems in the one-component developing method, the carrier is held only on the developer carrying member for the purpose of assisting the charging of the toner on the developer carrying member, and the delay of the rising of the toner charging or The 1.5-component developing method for improving the width of the charge distribution is effective and has been put into practical use.

However, in the 1.5-component developing system, the carrier exists only on the developer carrying member, and the toner and the developer newly added to the developer found in the conventional two-component developing system are added. Since there is no mixing device for mixing, in particular in a high-temperature and high-humidity environment, the toner added on the developer carrying member is liable to have a defective start-up of charging, resulting in low developability and background fog. As described above, there is still no sufficient small-sized image forming method that is satisfactory in density, image quality, and environmental stability.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation in the prior art, and has as its object to solve the problem. That is, a first object of the present invention is to provide an image forming method which can use a small image forming apparatus which is excellent in terms of space saving. A second object of the present invention is that the developer has a good start-up of charging, has a sharp charge distribution, and has a long life and is small in size, which is unlikely to cause problems of low developability, uneven density, and development ghost. An object is to provide an image forming method applied to an image forming apparatus.

[0007]

As a result of intensive studies, the present inventors have omitted a mixing device for holding a carrier only on a developer carrying member and mixing a newly added toner with a developer. This makes it possible to downsize the device and suppress development ghosts.By using a developer carrier having a nickel layer on the surface, problems such as environmental dependence, low developability, uneven density, and durability can be avoided. They have found that they can be solved, and have completed the present invention.

That is, according to the image forming method of the present invention, the step of forming a latent image on the latent image holding member is performed by using the developer carried on the developer carrying member in the developing device. A step of forming a toner image on the surface, a step of transferring the toner image onto a transfer body, and a cleaning step of removing the residual toner on the latent image holding body, wherein the developing device has a nickel layer on the surface. A developer carrier and a toner chamber that is located behind it and contains only a toner are used, and a developer composed of toner and a magnetic carrier is used, and the magnetic carrier is the developer carrier. It is characterized in that the development is performed under the condition existing only above.

FIG. 1 illustrates the state of the developer carried on the developer carrier in the step of forming a toner image in the present invention, 3 being a developer carrier and 8 being a developer carrier. Reference numeral 81 is a toner, which is a developer including toner and a magnetic carrier. In the present invention, the development is carried out while the magnetic carrier of the developer is carried on the developer carrier together with the toner.

[0010]

FIG. 2 shows an example of an electrophotographic apparatus used in the image forming method of the present invention. In the figure, a roller charger 2 is provided around a latent image carrier 1.
A developing device 4 provided with a developer carrying member 3, a roller transfer device 5, and a blade type cleaner 6 are provided, and a toner chamber 41 is provided behind the developer carrying member 3 provided in the developing device 4. The toner is filled in the toner chamber. Reference numeral 7 is a developer layer thickness regulating member.

In the image forming method of the present invention, first,
In the step of forming a latent image on the latent image holding member, the latent image holding member 1 such as a photosensitive drum is uniformly charged by the roller charger 2, and then reverse exposure is performed by a laser writing device (not shown), Form a latent image. Next, the latent image carrier 1 that holds the formed latent image moves to a position facing the developer carrier 3 that carries the developer, and the latent image is developed by the developer to form a toner image. To be done.
In this case, the developer layer thickness regulating member 7 is adjusted to an appropriate distance on the developer carrying member 3 so that the magnetic carrier is carried together with the toner, whereby almost all of the magnetic carrier is formed. Will be carried on the developer carrier. The toner image formed as described above is then transferred onto a transfer member such as paper by the roller transfer device 5, while the toner remaining on the latent image holding member is cleaned by the blade cleaner 6. , For the next copying process.

In the present invention, the latent image carrier is
An electrophotographic photoreceptor or a dielectric for electrostatic recording can be used. The electrophotographic photoreceptor has a photosensitive layer on a cylindrical support, and as the photosensitive layer, known materials such as organic type and amorphous silicon can be used. The cylindrical support can be obtained by a known manufacturing method such as extruding aluminum or an aluminum alloy and then surface-treating it.

The developer carrying member used in the present invention has a nickel layer on the surface, and it can be prepared by a known manufacturing method in which aluminum or an aluminum alloy is extruded and then plated on the surface with nickel. it can. The nickel layer formed on the surface has a thickness of 1 to 20 μm.
Are preferred. Further, the surface of the nickel layer may be appropriately roughened in order to improve the charging property and stabilize the formation of the developer layer.

As the toner in the present invention, a known toner comprising a colorant and a binder resin can be used. As the binder resin, a known resin conventionally used for toner can be used. For example, homopolymers and copolymers of one or more vinyl monomers. Typical vinyl monomers include, for example, vinyl aromatic compounds such as styrene, p-chlorostyrene, vinylnaphthalene, etc., ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene, etc., such as vinyl chloride and vinyl bromide. , Vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl formate, vinyl stearate, vinyl caproate, and other vinyl esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, acrylic acid Ethylenic monocarboxylic acids such as isobutyl, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl-α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and the like. Tellurines, acrylonitrile, methacrylonitrile, ethylenic monocarboxylic acid substitution products such as acrylamide, for example, dimethyl maleate, diethyl maleate, dibutyl maleate and other ethylenic carboxylic acids and esters thereof, for example vinyl methyl ketone, vinyl hexyl Ketones, vinyl ketones such as methyl isopropenyl ketone, for example vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, etc., vinylidene halides such as vinylidene chloride, vinylidene chloride, etc., for example N-vinylpyrrole, Examples include N-vinyl compounds such as N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone.

Examples of the colorant include carbon black, azine dyes such as nigrosine, chromium dyes such as chromium salicylate complex, aniline blue, chrome yellow, ultramarine blue, methylene blue chloride, phthalocyanine blue, rhodamine 6G lake, and the like. Any known material can be used. Further, a magnetic material can be contained as a coloring agent. Examples of the magnetic material include metals such as iron, cobalt and nickel and alloys thereof, Fe ₃ O ₄ , γ-Fe ₂ O ₃ , metal oxides such as cobalt-added iron oxide, MnZn ferrite and N.
Any known ferrite such as iZn ferrite can be used. The content of the colorant is appropriately set, but in general, it may be used within the range of 1 to 50% by weight for dyes and pigments and 20 to 80% by weight for magnetic materials with respect to the total amount of toner.

In the toner used in the present invention, for the purpose of charge control, electric resistance control, etc., various materials, for example, polymeric acids such as copolymers containing maleic acid as a monomer component, quaternary An ammonium salt or the like may be contained, but when used in a color toner, it is desirable to select one having a range that does not impair the color tone. Furthermore, in order to make offset resistance more complete, a releasing agent may be added. As the release agent, paraffins having 8 or more carbon atoms, polyolefins and the like are preferable, and for example, paraffin wax, paraffin latex, microcrystalline wax and the like can be used.

In the developer of the present invention, for the purpose of further improving the chargeability, durability, fluidity or cleaning property of the toner, inorganic fine powder such as silica and titania, fatty acid or its derivative and metal salt. It is also possible to add an organic fine powder such as the above, a resin fine powder such as a fluororesin, an acrylic resin or a styrene resin as an external additive. They may be subjected to a surface treatment such as a hydrophobic treatment with a silane coupling agent, silicol oil or the like.

In the present invention, the magnetic carrier is developed so that it exists only on the developer carrying member as shown in FIG. 1 as described above, but as the carrier usable in the present invention, iron powder is used. , Various ferrite powders, various magnetite powders, various metal powders, and the like. If necessary, a resin coating layer may be provided on the surface of these for the purpose of adjusting the charge. Further, particles obtained by melt-kneading the binder resin and the magnetic powder, pulverizing, and classifying, or particles obtained by melt-kneading the binder resin and the magnetic powder, granulating by cooling with a powder mist, that is, A so-called dispersion type magnetic carrier can also be preferably used. Further, various pigments and dyes may be kneaded at the same time for the purpose of charge adjustment. In these dispersion-type magnetic carriers, all of the binder resins, magnetic powders, charge control agents and the like exemplified for toner can be used.

In the present invention, it is necessary that the charge exchange property when a new toner is added on the developer carrying member is good and that the newly added toner rises in charge quickly. Therefore, in addition to the carrier charge control method described above,
Fine powder of metal oxide such as titanium oxide as a charge exchange promoter for carrier, fine powder of organic acid such as fatty acid or its derivative and metal salt, fine powder of resin such as fluorine resin, acrylic resin or styrene resin, carbon black, etc. Fine powder of may be added. A surface treatment such as a hydrophobic treatment may be applied to the surface of the fine powder. In particular, if the carrier is iron powder, various ferrite powders, various magnetite powders, or metal powder provided with a resin coating layer, the resin coating layer is doped with a conductive powder such as a metal oxide or carbon black as a charge exchange accelerator. Alternatively, a resin coating layer may be provided so that the surface of the metal powder is partially exposed.

As the magnetic carrier, those having a volume average particle diameter of 20 to 200 μm can be preferably used, and more preferably 30 to 100 μm. 20 μm
If it is less than 200 μm, the phenomenon that the magnetic carrier migrates from the developer carrying member to the photosensitive member is likely to occur, and if it is more than 200 μm, the original purpose of imparting charge to the toner becomes insufficient.

In the present invention, the compounding ratio of the toner and the magnetic carrier in the developer on the developer carrier can be set as appropriate, but the toner concentration in the developer on the developer carrier can be adjusted depending on the amount of the magnetic carrier. Is controlled, and when the carrier amount is large, the toner concentration is low, and when the carrier amount is small, the toner concentration is high.

Generally, the toner concentration is preferably in the range of 5 to 70% by weight of the developer, more preferably 10 to 50% by weight. If the toner density is lower than 5% by weight, density reduction and density unevenness are likely to occur when a print with high image density is obtained. On the other hand, when the content is higher than 70% by weight, charging of the toner by the magnetic carrier becomes insufficient, and density decrease, density unevenness, background fog and the like are likely to occur.

The particle size of the toner and carrier used in the present invention is the particle size measuring device T manufactured by Coulter Counter.
It is a value measured with an A-II aperture diameter of 100 μm.
Further, the roughness of the unevenness of the surface of the toner carrier is a value measured by a Safcom surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd.
a is based on “JIS B0601”.

[0024]

Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited by these. Example 1 Production of developer carrier: Aluminum was extruded to obtain a cylindrical substrate having an outer diameter of 16 mm and a length of 250 mm.
Irregular brown alumina abrasive material A (JIS R6111-1
Blast treatment according to 987) was performed. Next, after forming a Zn underlayer on the substrate by electroless plating using an aqueous solution containing about 10 g of Zn and about 100 g of NaOH in 1 liter, the surface of the substrate is further subjected to electroless nickel plating to form a nickel layer. Was formed. Then, a developer carrying member was obtained by inserting a 700 g magnet inside. The surface roughness of the obtained developer carrying member is Ra:
The thickness of the nickel layer was 2.0 μm and the thickness of the nickel layer was 2.8 μm.

Toner production: Binder resin: Styrene-n-butyl acrylate 46 parts by weight (80/20) copolymer (weight average molecular weight 130000) Magnetic powder: magnetite 50 parts by weight Charge control agent: azo Fe dye 1 Parts by weight (T-77, Hodogaya Chemical Co., Ltd.) Release agent: Low molecular weight polypropylene 3 parts by weight (Viscor 660P, Sanyo Kasei Co., Ltd.) The mixture having the above composition was heated and melted and kneaded by an extruder, and then pulverized, The particles were classified to obtain particles having a volume average particle diameter of 6 μm. 1 particle diameter per 100 parts by weight of the obtained particles
1 part by weight of 5 nm hydrophobic colloidal silica was externally added with a Henschel mixer to obtain a toner.

Preparation of carrier: 15 parts by weight of a methylmethacrylate-styrene-vinylpyrrolidone (78: 20: 2) copolymer was dissolved in 100 parts by weight of toluene. The obtained solution was added to 2000 parts by weight of spherical ferrite having a volume average particle diameter of 50 μm, and a coating treatment was performed using a vacuum kneader coater. Then, the above materials were mixed in a 1 liter small kneader equipped with a heater at room temperature for 5 minutes, then the heat medium temperature was raised to 200 ° C., and the mixture was stirred and kneaded for 40 minutes. After that, stop heating with the heater,
Cooled with stirring for 50 minutes. Then, sieving was performed with a 105 μm sieve to obtain a magnetic carrier.

Next, the developer carrying member is attached to the developing device so as to have the structure shown in FIG. 2, and 15 g of the carrier is held on the developer carrying member 3 and then toner is introduced to increase the temperature and temperature. A copy test was performed under a humid environment (30 ° C., 80% RH), and the image quality at the initial stage and after printing 20,000 sheets was evaluated for image density, uneven density, and ghost.

Here, the aluminum developer layer thickness regulating member 7 was opposed to the developer carrying member 3 at a distance of 0.5 mm to form a thin layer of the developer. The latent image holding member 1 and the developer carrying member 3 were arranged at a distance of 0.4 mm. As an operation condition, after the latent image holder 1 is charged to -400 V by the roller charger 2, reverse exposure (image area exposure) is performed using a semiconductor laser writing device to expose the exposed area-
An electrostatic latent image having a surface potential of 50 V and an unexposed portion of -400 V was formed. Then, -300V is applied to the developer carrying member 3.
Was applied to develop the electrostatic latent image. At that time, the peripheral speed of the latent image carrier 1 was set to 60 mm / s, and the peripheral speed of the developer carrying member 3 was set to 150 mm / s. Further, the toner image was transferred onto the transfer paper by using the roller transfer device 5, and the toner remaining on the latent image holding member was cleaned by using the blade type cleaner 6. As a result of the above copy test, 20000
Images with high image density and no density unevenness or ghost were obtained until the end of printing on one sheet. The test results are shown in Table 1. The image density (SAD) was measured by an X-rite densitometer.

Example 2 Production of Carrier: Binder Resin: Styrene-n-butyl acrylate 25 parts by weight (80/20) Copolymer (weight average molecular weight 300,000) Magnetic powder: Magnetite 70 parts by weight (EPT-1000, Toda) Kogyo Co., Ltd.) Charge control agent: 8-nylon 5 parts by weight The above components are melt-kneaded by a pressure kneader, and further pulverized and classified using a turbo mill and a classifier to obtain a magnetic carrier having a volume average particle diameter of 40 μm. . Evaluation was performed in the same manner as in Example 1 except that 8 g of the above magnetic carrier was used instead of the magnetic carrier in Example 1.

Example 3 Production of Toner: Binder resin: Styrene-n-butyl acrylate 84 parts by weight (80/20) copolymer (weight average molecular weight 130000) Colorant: carbon black 10 parts by weight (BP1300, Cabot Corporation) Release agent: 6 parts by weight of low molecular weight polypropylene (Viscole 660P, manufactured by Sanyo Kasei Co., Ltd.) A mixture having the above composition is heated and melted and kneaded by an extruder, and then pulverized and classified to obtain particles having a volume average particle diameter of 7 μm. Obtained. 1 particle diameter per 100 parts by weight of the obtained particles
0.8 part by weight of 5 nm hydrophobic colloidal silica was externally added with a Henschel mixer to obtain a toner. Evaluation was performed in the same manner as in Example 1 except that the above toner was used.

Comparative Example 1 Evaluation was carried out in the same manner as in Example 1 except that the surface of the developer bearing member was not plated with nickel. Comparative Example 2 Developer layer thickness regulating member 7 in the image forming apparatus shown in FIG.
To the urethane rubber developer layer thickness control member,
As shown in, except that the developer layer regulating member 7a is brought into contact with the developer carrying member 3 at a linear pressure of 0.5 N / cm, and only the toner is used as the developer without using the magnetic carrier. Was evaluated in the same manner as in Example 3. The other reference numerals in FIG. 3 are the same as those in FIG.

Table 1 below shows the evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2.

[Table 1] Density unevenness ○: Density difference less than 0.05, △: Density difference 0.0
5 to less than 0.3, x: density difference of 0.3 or more Ghost: o: not generated, Δ: density difference to less than 0.3, x:
Density difference of 0.3 or more

[0033]

In the image forming method of the present invention, the developer carrier having the nickel layer on the surface is used as described above, and the toner particles containing the binder resin and the colorant as the developer and the magnetic property are used. Use one that consists of a carrier,
And at the time of development, since the development is carried out under the condition that the magnetic carrier exists only on the developer carrying member, the rise of the charge of the developer is good, and the charge distribution is sharp, the environmental dependence, the density unevenness, The problem of development ghost does not easily occur, and a high-quality image having a long life, high density, and no density unevenness and development ghost can be created by a small image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram showing a process of forming a toner image of the present invention,
FIG. 6 is an explanatory diagram illustrating a state of a developer carried on a developer carrying body.

FIG. 2 is a schematic configuration diagram of an image forming apparatus for carrying out the present invention.

FIG. 3 is a schematic configuration diagram of an image forming apparatus used in Comparative Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Latent image holding member, 2 ... Roller charging device, 3 ... Developer carrying member, 4 ... Developing device, 41 ... Toner chamber, 5 ... Roller transfer device, 6 ... Blade type cleaner, 7 ... Developer layer thickness regulating member , 8 ... Developer, 81 ... Toner.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroe Okuyama, 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor, Kotaro Yoshihara, 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor Masahiro Uchida 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (1)

[Claims] 1. A process of forming a latent image on a latent image carrier, a process of forming a toner image on the latent image carrier using a developer carried on a developer carrier in a developing device, In an image forming method including a step of transferring the toner image onto a transfer body and a cleaning step of removing the residual toner on the latent image holding body, a developing agent carrying body having a nickel layer on the surface and a rear side thereof are provided as the developing device. A developer having a toner chamber containing only the toner located therein is used, and as a developer,
An image forming method comprising using a toner and a magnetic carrier, and performing the development under the condition that the magnetic carrier exists only on the developer carrying member.