JP3327121B2 - Image forming method and image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming method and an image forming apparatus. More specifically, the present invention relates to an image forming method and an image forming apparatus for developing an electrostatic latent image formed on an electrostatic latent image carrier using a developer carried on the developer carrier.

[0002]

2. Description of the Related Art Conventionally, when an image is formed in a copying machine, a laser beam printer or the like, the Carlson method is generally used. In the Carlson method, an electrostatic latent image carrying roll is charged, and then the charged electrostatic latent image carrying roll is exposed by optical means to form an electrostatic latent image. The toner is adhered to the electrostatic latent image formed on the latent image carrying roll to form a toner image (visible image), and in a subsequent transfer step, the toner image is transferred to a recording medium such as recording paper, and the next fixing is performed. In the process, the toner image on the recording medium is fixed using heat, pressure or the like. After fixing, the electrostatic latent image carrying roll is cleaned by a cleaning device to prepare for the next copy, and the remaining toner is removed.

[0003] Of the above-mentioned processes, the developing method used for developing an electrostatic latent image includes a one-component developing method using only toner and a two-component developing method using toner and carrier, depending on the type of developer used. are categorized. Among them, the two-component developing method frictionally charges the toner by stirring the toner and the carrier, and by selecting the characteristics of the carrier and the stirring conditions, the frictional charge amount of the toner can be controlled to a considerable extent. It is preferably used because of its excellent image quality reliability.

A cascade method, a magnetic brush developing method, and the like are known as two-component developing methods. The magnetic brush developing method is excellent in reproducing not only line images but also solid images and continuous tones. It is preferably used.

The developing device for the magnetic brush developing method includes the above-described electrostatic latent image carrying roll, a developer carrying roll disposed in the vicinity of the electrostatic latent image carrying roll, a developer and a toner to be appropriately added. An auger that agitates the developer and a layer regulating member that regulates the thickness of the developer layer on the developer carrying roll and controls the amount of developer conveyed to the developing area. A developer in which the surface of the electrostatic latent image is erected in a brush shape by magnetic force on a developer carrying roll, that is,
Develop by rubbing with a magnetic brush.

[0006]

However, since this rubbing involves contact and collision between the toner and the carrier,
Inevitably damages both toner and carrier. For example, in a toner, an external additive added to the surface may be embedded in the toner, or a toner component may fall off.
In the carrier, the toner components including the external additive adhere to the surface of the carrier. If the carrier is a resin-coated carrier, abrasion and destruction of the carrier-coating component occur. For this reason, while using the developer repeatedly,
Initial characteristics are not exhibited, ground fog, in-flight dirt,
The image density fluctuates.

Therefore, in order to maintain stable quality during repeated use, it is necessary to minimize damage to the toner and the carrier, and the peripheral speed ratio of the developer carrying roll to the electrostatic latent image carrying roll must be reduced. It is necessary to reduce the contact force between the toner and the carrier and the impact force at the time of collision by lowering the pressure.

On the other hand, as a result of a detailed investigation by the present inventors, it has been found that after passing through the layer regulating member upstream of the developing device (pre-nip portion) and the gap between the layer regulating member and the developer carrying roll (nip portion). It was also found that the toner was triboelectrically charged on the developer carrying roll.

That is, at least a larger amount of developer than the amount of developer passing through the nip portion is transported to the pre-nip portion by the developer carrying roll, and the developer is transferred to the developer passing through the nip portion and the developer that cannot pass through. Split. The developer that cannot pass through the nip part stays in the pre-nip part as "accumulation". While staying in the pre-nip portion, the developer is agitated with the developer newly conveyed to the pre-nip portion, whereby the toner is charged by friction.
The frictional charging of the toner is also performed by the above-described rubbing, and not only the frictional charging due to the stirring of the auger, but also the desired charge amount of the toner is maintained by the frictional charging.

Therefore, if the peripheral speed ratio of the developer carrying roll to the electrostatic latent image carrying roll is reduced in order to reduce the impact force at the time of contact between the toner and the carrier, the triboelectric charging on the developer carrying roll becomes insufficient. Thus, it is expected that an appropriate charge amount is not provided to the toner.

Thus, it is possible to satisfy the conflicting requirements of reducing the mechanical damage applied to the toner and the carrier and quickly obtaining a proper and stable charge amount even with a weak contact or collision, and without impairing other characteristics. An image forming method and an image forming apparatus are desired.

The present invention has been made based on such studies. Accordingly, it is an object of the present invention to provide an image forming method and an image forming apparatus in which the damage of the developer is small.

Another object of the present invention is to provide a toner which is suitable for stabilizing the charge amount of toner in repetitive use of a copier,
Another object of the present invention is to provide an image forming method and an image forming apparatus which do not adversely affect other characteristics.

[0014]

The above objects can be achieved by the present invention described below.

That is, the present invention relates to an image forming method for developing an electrostatic latent image on an electrostatic latent image carrier using a developer layer on the developer carrier, the moving direction of the developer carrier. Are in the same direction as the moving direction of the electrostatic latent image carrier, and the peripheral speed ratio of the developer carrier to the electrostatic latent image carrier is 0.5 or more.
8 or less, wherein the developer is a carrier and a toner, and the carrier is a resin-coated carrier having a resin coating layer in which resin fine particles are dispersed and contained in a matrix resin on a core material; But thermosetting resin fine
An image forming method characterized by being particles .

According to the present invention, there is provided an image forming apparatus for developing an electrostatic latent image on an electrostatic latent image carrier using a developer layer on the developer carrier. The moving direction is the same as the moving direction of the electrostatic latent image carrier, and the peripheral speed ratio of the developer carrier to the electrostatic latent image carrier is 0.5 or more and 1.8 or less. And the developer carrying member, on a core material, holding a developer comprising a resin-coated carrier having a resin coating layer in which resin fine particles are dispersed and contained in a matrix resin, and a toner, wherein the resin particles, an image forming apparatus according to claim Oh Rukoto a thermosetting resin fine particles.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments.

FIG. 1 schematically shows an example of the image forming apparatus of the present invention. As shown in FIG. 1, the image forming apparatus of the present invention includes a photoconductor roll 3 as an electrostatic latent image carrier rotatable in the direction of arrow A (clockwise).
A charging device (not shown) such as a corona charger for charging the photoconductor roll 3, an exposure device (not shown) for exposing the charged photoconductor roll 3, a magnetic brush developing device, A transfer device (not shown) for transferring the toner image onto the recording medium, a fixing device (not shown) for fixing the image on the recording medium, and a cleaning device (not shown) for removing residual toner on the photoconductor roll 3 Is provided. Also,
The magnetic brush developing device includes a fixed magnet inside, and a developer carrying roll 1 as a developer carrying body rotatable in an arrow B direction (counterclockwise rotation direction); a developer carrying roll 1 and a photoconductor roll 3. A doctor blade (not shown) as a layer regulating member disposed upstream of the developing region formed in the vicinity of the developer carrying roll 1 and a toner replenisher (not shown); Auger (not shown). In this image forming apparatus, the electrostatic latent image 4 on the photoreceptor roll 3 is developed by a developer layer 2 (layer made of a magnetic brush) carried on a developer carrying roll 1 to form a toner image 5.

In this image forming apparatus, the moving direction of the developer carrying roll 1 in the developing area is the same as the moving direction of the photosensitive roll 3 in the developing area (forward direction). This prevents the formation of a streak-like abnormal image, and reduces the image in comparison with the case where the direction of movement of the developer carrying roll 1 in the developing area is opposite to the direction of movement of the photoconductor roll 3 in the developing area. The quality is improved.

On the other hand, the amount of toner adhering to the electrostatic latent image depends on the relative speed between the peripheral speed of the photoreceptor roll 3 and the peripheral speed of the developer carrying roll 1, so that the forward developing Conventionally, the peripheral speed ratio of the developer carrying roll 1 to the photoreceptor roll 3 has been set to 2.0 or more in order to secure a desired amount of toner adhesion. In the present invention, by setting the peripheral speed ratio to 0.5 to 1.8, the mechanical pressure applied to the developer can be reduced, and the useful life of the developer can be extended. Here, it is not preferable that the peripheral speed ratio is less than 0.5, because the toner transport amount becomes too small, and the developing density tends to decrease. On the other hand, when the peripheral speed ratio exceeds 1.8, the energy at the time of collision becomes large, the damage to the toner and the carrier is large, and the life of the developer is shortened. The peripheral speed ratio is preferably in a range from 0.7 to 1.6.

In the above-described image forming apparatus, if it is desired to supplement the amount of toner transported to the developing area, it is preferable to apply an AC bias toward the developing area in addition to the DC bias. This AC bias is usually 1k
V to 4 kV, particularly preferably 1.4 to 2.5 kV
It is. The frequency used at this time is generally in the range of 1 to 10 kHz.

When the peripheral speed ratio of the developer-carrying roll 1 to the photoreceptor roll 3 is reduced to 0.5 to 1.8, the number of contacts between the toner and the carrier decreases as the mechanical force decreases. It is considered that the charge exchange between the toner and the carrier is reduced, and the charging speed of the toner added to the developing device becomes slow particularly during continuous use for a long time.

However, the carrier used in the present invention is a resin-coated carrier, and the resin coating layer contains a matrix resin and fine resin particles dispersed in the matrix resin. As a result, the charging speed of the toner can be appropriately maintained. That is, in the carrier used in the present invention, the carrier surface area per unit weight is large, so that the probability of contact with the toner is increased, whereby the speed of charge exchange between the toner and the carrier can be increased. In particular, the charge amount of the toner can be promptly set to an appropriate charge level, and the charge amount can be stabilized. Moreover, unlike a normal carrier in which the surface area is reduced due to abrasion due to long-term use, even if the resin coating layer is worn, the same surface composition and surface area as when not used are maintained by the fine resin particles dispersed in the matrix resin. As a result, good charge-imparting ability can be maintained for the toner.

As described above, according to the present invention, the conflicting demands of improving the service life of the developer, stabilizing the charge amount, stabilizing the image quality and preventing fogging can be satisfied, and adversely affects other characteristics. Has no effect.

The resin fine particles contained in the resin coating layer used in the present invention is relatively easy to increase the hardness thermosetting resin fine particles are used.

As the thermosetting resin, a phenol resin,
Epoxy resins, diallyl phthalate resins, unsaturated polyester resins, melamine resins, urea resins, alkyd resins, benzoguanamine resins and the like can be mentioned.

Further, the coating resin fine particles used in the present invention, in order to impart negative charge to the toner, it is not preferable containing N (nitrogen) atoms as a constituent component. This
The "resin fine particles containing the N atom" in this, specifically, crosslinked or non-crosslinked melamine resin, a polyamide resin.

The average particle size of the resin fine particles is preferably 0.1 to 2 μm. More preferably, it is 0.2 to 1 μm. If it is smaller than 0.1 μm, the dispersion in the resin coating layer is very poor, and if it is larger than 2 μm, it tends to drop off from the resin coating layer and the original function cannot be maintained.

The resin fine particles are contained in an amount of 5% by weight to 50% by weight, particularly 5% by weight to
It is preferable to contain it in the range of 30% by weight. When the amount is less than 5% by weight, the toner cannot sufficiently exhibit charge,
When the content is more than the weight%, the resin fine particles easily fall off from the carrier surface.

Examples of the method for producing the above resin fine particles include: suspension polymerization; emulsion polymerization; suspension polymerization; a method in which a monomer or oligomer is dispersed in a poor solvent and granulated by surface tension while performing a crosslinking reaction; And a cross-linking agent are mixed and reacted by melt kneading or the like, and then pulverized to a predetermined particle size by wind force or mechanical force.

It is preferable that the fine resin particles are uniformly dispersed in the matrix resin. Further, the resin fine particles are preferably harder than the matrix resin. By using the hard resin fine particles, the unevenness of the surface of the resin coating layer can be maintained and the wear of the resin coating layer can be reduced.

As the matrix resin of the resin coating layer of the carrier used in the present invention, a polyolefin resin,
For example, polyethylene, polypropylene; polyvinyl and polyvinylidene resins, for example, polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate,
Polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin comprising organosiloxane bond or a modified product thereof; Resins, such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate; phenolic resin;
For example, urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, epoxy resin and the like can be mentioned. These resins may be used alone or in combination of two or more. The matrix resin and the resin of the resin fine particles may be the same or different.

The above matrix resin has a critical surface tension of 35 dyne / cm for the purpose of suppressing contamination of the carrier surface.
The following resin is preferably used, and more preferably 30 dyne / cm or less.

Critical surface tension 35 to provide a low energy surface
Examples of the resin having a dyne / cm or less include the following resins.

That is, polystyrene (γc = 33 dyne / c
m), polyethylene (γc = 31 dyne / cm), polyvinyl fluoride (γc = 28 dyne / cm), polyvinylidene fluoride (γc = 25 dyne / cm), polytrifluoroethylene (γc = 22 dyne / cm), polytetrafluoroethylene (Γc = 18 dyne / cm), polyhexafluoropropylene (γc = 16 dyne / cm), and the like, a copolymer of vinylidene fluoride and an acrylic monomer, and a copolymer of vinylidene fluoride and vinyl fluoride And a fluoroterpolymer such as a terpolymer of tetrafluoroethylene, vinylidene fluoride and a non-fluorinated monomer and having a critical surface tension of 35 dyne / cm or less.

It is particularly preferable to contain a fluorine-containing resin, polymer and / or silicone resin having a critical surface tension of 30 dyne / cm or less.

The carrier core material used in the present invention includes magnetic metals such as iron, steel, nickel, and cobalt; magnetic oxides such as ferrite and magnetite; and glass beads. From the viewpoint of using a magnetic brush method. Is
Preferably, it is a magnetic carrier. The average particle size of the carrier core material is generally 10 μm to 500 μm, and preferably 30 μm to 100 μm.

As a method of forming a resin coating layer containing fine resin particles and a matrix resin on the surface of a carrier core material, for example, a method of forming a resin coating layer containing a matrix resin, fine resin particles and a solvent by powdering the carrier core material is used. Dipping method in which the carrier core material is sprayed on the surface of the carrier core material, and a fluidized bed in which the carrier core material is sprayed with the carrier core material suspended by flowing air. A method of mixing a carrier core material and a solution for forming a resin coating layer in a kneader coater to remove the solvent may be mentioned. In the present invention, the kneader coater method is particularly preferably used.

The solvent used for the resin coating layer forming solution is
There is no particular limitation as long as it dissolves the matrix resin. For example, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ethyl ketone, and ethers such as tetrahydrofuran and dioxane can be used.

The coating amount of the resin coating layer is 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight per 100 parts by weight of the core material.
It is in the range of parts by weight.

As the toner used in the present invention, either a black toner or a color toner can be used, and the toner contains a colorant and a binder resin. Colorants include carbon black, nigrosine, aniline blue, calcoil blue,
Chrome Yellow, Ultramarine Blue, Dupont Oil Red, Quinoline Yellow, Methylene Blue Chloride, Phthalocyanine Blue, Malachite Green Oxalate, Lamp Black, Rose Bengal, C.I. I.
Pigment Red 48: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 57: 1,
C. I. Pigment Yellow 97, C.I. I. Pigment Yellow 12, C.I. I. Pigment Blue 15:
1, C.I. I. Pigment Blue 15: 3 and the like can be exemplified as typical examples.

Examples of the binder resin include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl acetate, and acrylic acid. Α-methylene aliphatic monocarboxylic acid esters such as methyl, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, vinyl Homopolymers or copolymers such as vinyl ethers such as methyl ether, vinyl ethyl ether and vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone can be exemplified. Particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-maleic anhydride. Copolymers, polyethylene and polypropylene can be mentioned. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin, and wax can be used. Among them, it is particularly effective when polyester is used as the binder resin. For example, a linear polyester resin comprising a polycondensate containing bisphenol A and a polyvalent aromatic carboxylic acid as main monomer components can be preferably used.

The binder resin has a softening point of 90 to 150.
° C, glass transition point 50-70 ° C, number average molecular weight 20
00-6000, weight average molecular weight 8,000-15,000
A resin having 0, an acid value of 5 to 30, and a hydroxyl value of 5 to 40 can be particularly preferably used.

The toner particles may further contain known additives such as a charge control agent and a fixing aid, if desired.

[0045]

EXAMPLES The present invention will be described below with reference to examples.
This does not limit the present invention. Manufacture of carrier [Carrier A] Ferrite particles (average particle size; 50 μm) 100 parts by weight Toluene 16 parts by weight Styrene-methyl methacrylate copolymer (copolymerization ratio 6: 4, weight average molecular weight Mw: 50,000, critical surface tension 35 dyne 0.8 parts by weight Phenol resin particles (average particle size: 0.6 μm, insoluble in toluene) 0.2 parts by weight The above components excluding ferrite particles are dispersed with a stirrer for 10 minutes to prepare a solution for forming a resin coating layer. Further, the solution for forming a resin coating layer and ferrite particles were put into a vacuum degassing type kneader, stirred at a temperature of 60 ° C. for 30 minutes, and then toluene was distilled off under reduced pressure to form a resin coating on the ferrite particles. A layer was formed to obtain a carrier. [Carrier B] Ferrite particles (average particle size: 50 μm) 100 parts by weight Toluene 16 parts by weight Styrene-methyl methacrylate copolymer (copolymerization ratio 6: 4, weight average molecular weight Mw: 50,000, critical surface tension 35 dyne / cm) 0.6 parts by weight Nylon resin particles (average particle size: 0.4 μm, insoluble in toluene) 0.3 parts by weight The above components except for the ferrite particles are dispersed by a homomixer for 10 minutes to prepare a resin coating layer forming solution. Further, the solution for forming a resin coating layer and the ferrite particles were placed in a vacuum degassing type kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then toluene was distilled off under reduced pressure to form a resin coating layer on the ferrite particles. Formed to obtain a carrier. [Carrier C] Ferrite particles (average particle size: 45 μm) 100 parts by weight Toluene 16 parts by weight Perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymerization ratio 3: 7, weight average molecular weight Mw: 50,000, critical surface tension) 24 dyne / cm) 0.7 parts by weight Crosslinked methyl methacrylate resin particles (average particle size: 0.3 μm, insoluble in toluene) 0.2 parts by weight The above components excluding ferrite particles are dispersed with a stirrer for 10 minutes to form a resin coating layer. The solution was prepared, and the solution for forming a resin coating layer and the ferrite particles were placed in a vacuum degassing kneader and stirred at a temperature of 60 ° C. for 30 minutes. A carrier was obtained by forming a resin coating layer on the substrate. [Carrier D] Ferrite particles (average particle size: 45 μm) 100 parts by weight Toluene 16 parts by weight Perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymerization ratio 3: 7, weight average molecular weight Mw: 50,000, critical surface tension) 24 dyne / cm) 0.8 parts by weight Crosslinked melamine resin particles (average particle size: 0.3 μm, insoluble in toluene) 0.2 parts by weight The above-mentioned components excluding ferrite particles are dispersed with a stirrer for 10 minutes to form a resin coating layer forming solution Further, this solution for forming a resin coating layer and ferrite particles were put in a vacuum degassing type kneader, and stirred at a temperature of 60 ° C. for 30 minutes. A carrier was obtained by forming a resin coating layer. [Carrier E] A carrier was obtained in the same manner as in Example 1, except that the phenol resin particles were omitted. [Carrier F] Ferrite particles (average particle size: 45 μm) 100 parts by weight Toluene 14 parts by weight Perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymerization ratio 3: 7, weight average molecular weight Mw: 50,000, critical surface tension) 24 dyne / cm) 0.5 parts by weight Methyl methacrylate-dimethylethyl methacrylate copolymer (copolymerization ratio 8: 2, weight average molecular weight Mw: 70,000, critical surface tension 40 dyne / cm) 0.3 parts by weight Excluding ferrite particles The above components were dispersed with a stirrer for 10 minutes to prepare a solution for forming a resin coating layer, and the solution for forming a resin coating layer and ferrite particles were placed in a vacuum degassing kneader and stirred at a temperature of 60 ° C. for 30 minutes. Thereafter, toluene was distilled off under reduced pressure, and a resin coating layer was formed on the ferrite particles to obtain a carrier. [Carrier G] Ferrite particles (average particle size: 45 μm) 100 parts by weight Toluene 16 parts by weight Perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymerization ratio 3: 7, weight average molecular weight Mw: 50,000, critical surface tension) 24 dyne / cm) 0.8 parts by weight Uncrosslinked melamine resin (critical surface tension 65 dyne / cm) 0.2 parts by weight The above components except for ferrite particles are dispersed with a stirrer for 10 minutes to prepare a resin coating layer forming solution. Further, the solution for forming a resin coating layer and the ferrite particles were placed in a vacuum degassing type kneader, stirred at a temperature of 60 ° C. for 30 minutes, and the pressure was reduced to remove toluene. Thereafter, the mixture was further stirred at a temperature of 150 ° C. for 60 minutes to form a resin coating layer containing a crosslinked melamine resin on the ferrite particles to obtain a carrier. Production of Toner Particles [Toner A] 100% by weight of linear polyester resin (linear polyester obtained from terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol; Tg = 62 ° C., Mn = 4) 000, Mw = 35,000, acid value = 12, hydroxyl value = 25) Magenta pigment (CI Pigment Red 57) 3% by weight The above mixture was kneaded with an extruder, pulverized with a jet mill, and then subjected to wind power. Dispersed by a type classifier and d50 = 8 μm
Magenta toner (color toner) particles were obtained. R972 (silica; manufactured by Nippon Aerosil Co., Ltd.) was added to the magenta toner particles with a 0.4% by weight Henschel mixer to obtain a magenta toner (toner A). [Toner B] Styrene-n-butyl methacrylate 94% by weight (70/30) copolymer (Mn = about 7,000, Mw = about 40,000) Carbon black (Mogal L; manufactured by Cabot Corporation) 6% by weight The mixture was kneaded with an extruder, pulverized with a pulverizer using a combination of surface pulverization and volume pulverization, and then classified into fine particles and coarse particles with a wind-type classifier to obtain d50 = 9 μm black toner particles. R972 (silica; Nippon Aerosil Co., Ltd.) was added to the black toner particles with a 0.6% by weight Henschel mixer to obtain a black toner (toner B). (Example 1) Preparation of developer Using the toner A and the carriers A to D, 7 parts by weight of each of the toner compositions described above was added to 100 parts by weight of the carrier, and mixed with a V blender. Developers 1 to 4 for evaluation were used.

An electrophotographic copier (A-Color 630, manufactured by Fuji Xerox Co., Ltd.) was modified (using a developer carrying roll with a peripheral speed ratio of 0.7 with respect to the photosensitive member) by using the developers 1 to 4. A copy test was performed. Medium temperature and humidity (2
When a copy test of 10,000 sheets was performed using these developers in an environment of 2 ° C. and 55% RH), a stable image was obtained without fluctuation in image density and background smear. The charge amount was measured at the initial stage, after 1,000 sheets, and after 10,000 sheets.

The results obtained are shown in Table 1 below. The table
In Example 1, the resin-coated carriers B and C
Is a reference example in the first embodiment. An electrophotographic copying machine (A-Color) is used by using developers 1-4.
630, manufactured by Fuji Xerox Co., Ltd. (the peripheral speed ratio of the developer-carrying roll to the photosensitive member was 1.4). Medium temperature and humidity (22 ° C, 55% R
When a copy test of 10,000 sheets was performed using these developers in the environment of H), a stable image was obtained without any change in image density or background smear. The charge amount was measured at the initial stage, after 1,000 sheets, and after 10,000 sheets.

Note that the charge amount is a value obtained by image analysis of CSG (charge spectrograph method).

The results obtained are shown in Table 2 below. The table
In Example 1 of Example 2, resin-coated carriers B and C
Is a reference example in the first embodiment. When the developer of the present invention was used, the peripheral speed ratio was 0.7, 1.4.
Also, the charge amount hardly changed. (Example 2) Preparation of developer Using the toner B and the carriers A to D, 7 parts by weight of each of the toner compositions described above was added to 100 parts by weight of the carrier, and mixed with a V blender. Developers 5 to 8 for evaluation were used.

Using these developers 5 to 8, an electrophotographic copying machine (A-Color 630, manufactured by Fuji Xerox Co., Ltd.) was modified (the peripheral speed ratio of the developer carrying roll to the photosensitive member was 0.7, 1. A copy test was performed according to 4). There was no background fog, and high quality images with high density were obtained from the beginning.
Further, when continuous copying of 10,000 sheets was performed, almost no change in image quality was recognized.

The obtained results are shown in Tables 1 and 2 below. What
In addition, in Example 2 of Tables 1 and 2,
Those using carriers B and C are referred to in Example 2.
This is an example. (Comparative Example 1) Preparation of Developer Using the toner A and the carriers E to G, 7 parts by weight of each of the toner compositions described above was added to 100 parts by weight of the carrier and mixed with a V blender. Developers 9 to 11 for evaluation were used.

An electrophotographic copying machine (A-Color 630, manufactured by Fuji Xerox Co., Ltd.) using developers 9 to 11
A copy test was performed using the modified machine (the peripheral speed ratio of the developer carrying roll to the photosensitive member was 0.7). Medium temperature and humidity (2
A copy test of 1,000 sheets was performed using these developers in an environment of 2 ° C. and 55% RH). Initial charge amount and 1,000
The charge amount after 0 sheets was measured.

The results obtained are shown in Table 1 below. Developer 9
To 11 using an electrophotographic copying machine (A-Color6)
30, a copy test was also performed using a modified machine (manufactured by Fuji Xerox Co., Ltd.) (the peripheral speed ratio of the developer carrying roll to the photosensitive member was 1.4). Medium temperature and humidity (22 ° C, 55% R
When a copy test of 1,000 sheets was performed using these developers in the environment of H), a phenomenon similar to that when the peripheral speed ratio of the developer carrying roll to the photosensitive member was 0.7 was observed. .

Note that the charge amount is a value obtained by image analysis of CSG (charge spectrograph method).

The results obtained are shown in Table 2 below. (Comparative Example 2) An electrophotographic copying machine (A-Color630, manufactured by Fuji Xerox Co., Ltd.) using developers 1 to 11
A copy test was performed using a modified machine (the peripheral speed ratio of the developer carrying roll to the photosensitive member was 0.4). Medium temperature and humidity (2
When a copy test of 10,000 sheets was performed using these developers in an environment of 2 ° C. and 55% RH), the developer 1 to 8 was stable in the charge amount, but the image density was generally high. And low quality images were obtained. Further, with Developers 9 to 11, background dirt was found at the time of a 10,000-sheet copy test, and in-machine dirt was also observed. The charge amount was measured at the initial stage, after 1,000 sheets, and after 10,000 sheets.

The results obtained are shown in Table 3 below. (Comparative Example 3) A remodeling machine of an electrophotographic copying machine (A-Color 630, manufactured by Fuji Xerox Co., Ltd.) (peripheral speed of a developer-carrying roll with respect to a photoconductor, using a developer using developers 1 to 11) A copy test was performed according to a ratio of 2.4). When a copy test of 10,000 sheets was performed using these developers in an environment of medium temperature and humidity (22 ° C., 55% RH), the charge amount gradually decreased, and there was background contamination. Bad image was obtained. The charge amount was measured at the initial stage, after 1,000 sheets, and after 10,000 sheets.

The results obtained are shown in Table 4 below.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

[Table 3]

[0061]

[Table 4]

[0062]

According to the image forming method of the present invention, as described above, the peripheral speed ratio of the developer carrier to the electrostatic latent image carrier is 0.5.
And the carrier contained in the two-component developer is a resin-coated carrier coated with a resin, and the resin coating layer contains fine resin particles made of a specific material. Is improved, the charge distribution range is narrow, and even when used continuously for a long time, a stable charge amount is maintained, and a copy image with stable image quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a process of an image forming method of the present invention and an example of an image forming apparatus.

[Explanation of symbols]

 Reference Signs List 1 developer carrying roll 2 developer layer 3 photoreceptor roll 4 electrostatic latent image 5 image

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Chiaki Suzuki 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. (56) References JP-A-7-181746 (JP, A) JP-A-59-197056 ( JP, A) JP-A-8-286431 (JP, A) JP-A-5-6099 (JP, A) JP-A-5-265302 (JP, A) JP-A-2-284162 (JP, A) JP JP-A-7-271194 (JP, A) JP-A-7-175257 (JP, A) JP-A-62-295076 (JP, A) JP-A-3-73965 (JP, A) JP-A-8-6309 (JP JP-A-1-105264 (JP, A) JP-A-8-44118 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/00-9/113 G03G 13/08-13/095 G03G 15/08-15/095

Claims (7)

(57) [Claims] In an image forming method for developing an electrostatic latent image on an electrostatic latent image carrier using a developer layer on the developer carrier, the moving direction of the developer carrier is the electrostatic latent image. The peripheral speed ratio of the developer carrier to the electrostatic latent image carrier is 0.5 or more and 1.8 or less in the same direction as the moving direction of the latent image carrier;
And a developer comprising a carrier and a toner, wherein the carrier is a resin-coated carrier having, on a core material, a resin coating layer in which resin fine particles are dispersed and contained in a matrix resin, wherein the resin fine particles are thermosetting. An image forming method comprising resin fine particles . 2. The image forming method according to claim 1, wherein the amount of the resin coating layer is 0.05 to 5 parts by weight based on 100 parts by weight of the core material. 3. The image forming method according to claim 1, wherein the matrix resin is a resin having a critical surface tension of 35 dyne / cm or less. 4. An average particle diameter of a core material of the carrier is 30.
The thickness is not less than 100 μm and not more than 100 μm.
3. The image forming method according to any one of 3. 5. The image forming method according to claim 1, wherein the toner is a color toner. 6. The image forming method according to claim 1, wherein the toner contains a linear polyester binder resin. 7. An image forming apparatus for developing an electrostatic latent image on an electrostatic latent image carrier using a developer layer on the developer carrier, wherein the developer carrier moves in the moving direction. It is configured to be in the same direction as the moving direction of the electrostatic latent image carrier, and the peripheral speed ratio of the developer carrier to the electrostatic latent image carrier is 0.1.
5 or more and 1.8 or less, and the developer holding member holds a developer composed of a toner and a resin-coated carrier having a resin coating layer in which fine resin particles are dispersed and contained in a matrix resin on a core material. And the resin fine particles are thermosetting.
Oh Ru image forming apparatus of resin fine particles.