JPH10198175A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method which is adaptable to colors as well and is capable of achieving high image quality and long life with a small-sized and simple device without requiring intricate constitution and control. SOLUTION: This image forming method consists in developing the electrostatic latent image on an electrostatic latent image holding member 1 by disposing a magnetic carrier 4 on a mixing and agitating member 3 composed of a magnet roll including a permanent magnet in a sleeve, supplying the nonmagnetic toners 6 from a hopper 5 and subjecting the tones to triboelectrostatic charge by rotation of the permanent magnet or sleeve or both thereof, then supplying the developers to a developer carrying member 2 alternately arranged with magnetic poles of the polarities different from each other over the entire periphery with intervals of 25 to 250μm. The development is executed by setting the electric field peeling intensity at which 50% of the nonmagnetic toners move from the developers on the developer carrying member at <=1.0×10<6> V/m, the napping rate of the developers on the mixing and agitating members at <=0.15mm and the toner electrostatic charge quantity of the developers in the region where the developers subjected to the triboelectrostatic charge are supplied from the mixing and agitating member to the developer carrying member at a range of |15μc/g|<=QY<=|3-μc/g|.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method used in an image forming apparatus (image recording apparatus) such as an electrophotographic copying machine or a printer for forming a single-color or multi-color image, and more particularly to a developing method on a developer carrier. The present invention relates to a developing method in which a thin layer of a two-component developer is formed, carried and transported, and a developing bias voltage is applied to the developer carrier to develop an electrostatic latent image on the electrostatic latent image holding member.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, an electrostatic latent image formed on an electrostatic latent image holding member is developed by a developing means, and the developed image (visible image) is formed on a recording sheet. It is configured to transfer and copy an image. At that time, as a developing method for developing the electrostatic latent image formed on the electrostatic latent image holding member, a method employing a so-called two-component developing method using a two-component developer including a toner and a magnetic carrier is used. Many have been proposed. As a two-component developing method, a charge is applied to the toner by contact between the toner and the carrier, and a layer thickness regulating member called a trimmer is disposed at an appropriate distance from the developer carrier, and the toner is developed on the developer carrier. In general, a method of forming an agent layer and applying an electric field between the electrostatic latent image holding member and the developer carrying member to attach the toner to the electrostatic latent image is used. It is adopted as a developing method for many electrophotographic devices from the viewpoint of easiness of development.

In these electrophotographic apparatuses, a developing method in which a developer layer is not in contact with an electrostatic latent image holding member or a developing method in which a developer layer is lightly contacted to obtain a low-density, uniform, large-area image is adopted. For the purpose of increasing the development efficiency, developing while applying an AC bias to a developer carrying member is used as a usual means. In this case, a uniform mixing state of the developer and good chargeability without reverse polarity are required.

As a method of charging the toner and uniformly mixing it with the carrier, there is known a method of charging and uniformly dispersing the toner by a stirring and conveying mechanism such as an auger or paddle. However, when a stirring mechanism such as an auger or a paddle is used, an increase in the size and complexity of the apparatus is inevitable.
In order to solve this problem, in recent years, the following developing methods have been proposed from the viewpoint of high image quality and long life. That is, the magnetic carrier is adsorbed almost evenly on the developing carrier having an internal member having a plurality of magnetic poles at intervals of 25 μm to 250 μm and an outer peripheral member driven to rotate around the magnetic member, thereby supplying toner. A developing device and a developing method have been proposed in which a developing bias is applied between a developing carrier and a latent image holding member to carry out development in a non-contact state.

[0005] This developing method utilizes a method of charging toner by spinning a carrier by magnetic force on a sleeve, and several methods have been disclosed so far. For example, JP-A-2-291577, JP-A-63-287874, JP-A-5-188762
And JP-A-7-84456, in which toner is charged by spinning a carrier by magnetic force on a sleeve.

However, the above method has the following problems. That is, JP-A-2-2915
In the method disclosed in Japanese Patent No. 77, although the toner can be taken in by the spin motion of the carrier, the charge amount of the toner is insufficient, and it is necessary to provide a separate agitator, thereby solving the problem of an increase in size. Not something. In the case described in JP-A-63-287874, the rotation of the developer along the sleeve alone is not sufficient to cause the toner to adhere to the carrier surface, and it is necessary to provide a regulating plate. In that case, a secondary obstacle that the developer is deteriorated becomes a problem. Further, in the case of JP-A-5-188762 and JP-A-7-84456, it is not possible to adapt to colorization because a magnetic toner is used,
Further, when a non-magnetic toner is used, there is no magnetic binding force, and there is a specific problem that fog occurs unless the toner is charged reliably. Therefore, in the case of the above-mentioned method, there is no toner of the opposite polarity charged required in the non-contact developing method, that is, a good charge performance of a developer that can acquire the charge necessary for the development quickly by spinning the magnetic carrier, It is required that the toner that can be developed in a low electric field has a low peeling electric field performance, that is, the toner has a small adhesive force with the magnetic carrier, but a sufficient developing method that satisfies all of these requirements is still proposed. It has not been.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and is adaptable to color, small in size without complicated configuration and control. An object of the present invention is to provide an image forming method capable of achieving high image quality and long life with a simple device.

[0008]

According to the image forming method of the present invention, a magnetic carrier is arranged on a mixing and stirring member consisting of a sleeve and a magnet roll containing a permanent magnet in the sleeve, and the magnetic carrier is provided with a non-magnetic material. After the toner is supplied from the hopper to perform triboelectric charging by rotating the permanent magnet, the sleeve, or both, the magnetic poles having different polarities are alternately arranged over the entire circumference so that the interval between the magnetic poles is 25 μm to 250 μm. The developer is supplied onto the developer carrier arranged to develop the electrostatic latent image on the electrostatic latent image holder, and the developer on the developer carrier carries 50% of the non-magnetic toner from the developer. Is 1.0 × 10
⁶ V / m or less, and the amount of developer spikes on the mixing and stirring member is set to 0.15 mm or less, and development in a region where the triboelectrically charged developer is supplied from the mixing and stirring member to the developer carrier is performed. Toner charge amount (Q _Y ) of the agent is | 15 μc / g | ≦ Q _Y
Developing is performed in the range of ≦ | 30 μc / g |.

In the developer used in the present invention, the magnetic carrier has a particle diameter in the range of 20 to 50 μm, and has a magnetization characteristic of 30 to 7 μm.
It preferably has a range of 0 emu / g and a resistance value ≧ 10 ¹⁴ Ωcm. The non-magnetic toner is preferably manufactured by the following method. That is, a toner substance dispersed and dissolved in a solvent is mixed with a liquid that does not dissolve the toner substance, dispersed as droplets, and solidified as spherical particles by removing the solvent from the droplets. It is preferable that the degree of spheroidization is 120 or less. (In the present specification, “dispersion / dissolution” refers to a case where all of the toner substance is dissolved, and a case where a part of the toner substance is dissolved. Both when dispersed and other dissolved.) In particular, the non-magnetic toner is obtained by dispersing and dissolving a solution in which a charge control agent is previously dissolved in a solvent that is slightly soluble in a liquid that does not dissolve the toner substance, in a solvent together with other toner substances, and the resulting mixture is obtained. Is mixed with a liquid that does not dissolve the toner substance, dispersed as droplets, and solidified as spherical particles by removing the solvent from the droplets.

Further, in the image forming method of the present invention,
As means for supplying the non-magnetic toner to the magnetic carrier on the mixing and stirring member, a hopper provided with a flocked sealing material is provided so that the non-magnetic toner is supplied to a part of the surface of the mixing and stirring member. It is preferable that the non-magnetic toner is passed through the flocked sealing material while being mixed with the magnetic carrier so that the non-magnetic toner is in contact with the mixing and stirring member.

[0011]

Embodiments of the present invention will be described below in detail. In the image forming method of the present invention, a magnetic carrier is placed on a mixing and stirring member composed of a sleeve and a magnet roll containing a permanent magnet in the sleeve, and the nonmagnetic toner is placed on the magnetic carrier from a hopper. Then, the magnetic carrier is spun by an alternating magnetic field generated by the rotation of the permanent magnet, the sleeve, or both, and the developer carrier supply position Y immediately after the supply of the non-magnetic toner.
After the stirring and mixing and the triboelectric charging are performed in between, the magnetic poles having different polarities are alternately arranged on the entire circumference of the surface of the developer carrier, and the magnetic poles are alternately arranged on a developer carrier having an interval of 25 μm to 250 μm. The developer is supplied, and the developer on the developer carrier is sent in a non-contact state with the electrostatic latent image on the electrostatic latent image holder.

For example, FIG. 1 shows an example of a developing device for carrying out the image forming method of the present invention. Referring to FIG. 1, the non-magnetic toner 6 is put into the hopper 5, the mixing and stirring member 3 is constituted by a magnet roll having a permanent magnet included in a sleeve, and is placed on the magnet roll. Is magnetic carrier 4
Is placed. The non-magnetic toner is supplied to the magnetic carrier 4 on the sleeve by the rotation of the permanent magnet, the sleeve, or both, and the magnetic carrier is spun and conveyed by the alternating magnetic field, and the sealing members 7a, 7b in contact with the mixing and stirring member 3 , Stirring and mixing and frictional charging are performed between the non-magnetic toner supply position and the developer carrier supply position. Then, the developer sufficiently charged on the surface of the mixing and stirring member is placed on a developer carrier 2 having magnetic poles having different polarities alternately arranged on the entire circumference and provided on a developer carrier 2 provided at a constant gap. The developer layer is formed by being captured by the body's magnetic field. Next, development is performed by moving onto the electrostatic latent image of the electrostatic latent image holding member 1 installed at a predetermined interval.

The non-magnetic toner 6 is prepared by adding a colorant and, if necessary, a charge controlling agent and a release agent to the binder resin, kneading, pulverizing and classifying, and smoothing the surface with a hybridizer (manufactured by Nara Machinery Co., Ltd.). What was thrown into a spray dryer, instantaneously heated and made spherical by surface tension,
And spherical toners produced by various polymerization methods can be used, but from the viewpoint of developability, a toner substance dispersed and dissolved in a solvent is mixed with a liquid that does not dissolve the toner substance to form droplets. A toner produced by a method of producing particles by dispersing and coagulating as spherical particles by removing a solvent from droplets formed is desirable. In particular, a toner prepared by adding an external additive to the surface, for example, a spherical toner having an average particle diameter of 7 μm and having a sphericity of 120 or less is preferably used.

The toner shape (sphericity) is measured by an image analyzer (Luzex; Nireco).
The maximum length (ML) of the toner particles and the area (A) of the toner particles are measured by observing a two-dimensional projected image of the particles input from the optical microscope, and are values obtained by the following equation. (The closer the shape of the toner particles is to a sphere, the closer to 100.) Sphericity = (ML · 2 / A) × (π / 4) × 100

The binder resin is not particularly limited, and resins generally used as toner resins can be used. Specifically, polyester resin, styrene resin, acrylic resin, styrene / acrylic resin, silicone resin, epoxy resin, diene-based resin, phenolic resin, ethylene / vinyl acetate resin, and the like are preferable, and polyester resin is more preferable. . The following may be mentioned as the constituent monomer of the polyester resin. As the alcohol component, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene (3.3) -2,2-
Bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0)-
Diols such as polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, isopentyl glycol, Propylene glycol, isopentyl glycol, hydrogenated bisphenol A, 1,3-butanediol,
1,4-butanediol, neopentyl glycol, xylylene glycol, 1,4-cyclohexanedimethanol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, bis (β-hydroxyethyl) terephthalate, tris (β-hydroxy Ethyl) isocyanurate, 2,2,4-trimethylolpentane-1,3-diol and the like, and a hydroxycarboxylic acid component can be further added. Examples thereof include p-oxybenzoic acid, vanillic acid, dimethylolpropionic acid, malic acid, tartaric acid, and 5-hydroxyisophthalic acid. Specific examples of the acid component include malonic acid, succinic acid, glutaric acid, dimer acid, phthalic acid, isophthalic acid, terephthalic acid, isophthalic acid dimethyl ester, terephthalic acid dimethyl ester, terephthalic acid monomethyl ester, tetrahydroterephthalic acid,
Methyltetrahydrophthalic acid, hexahydrophthalic acid,
Dimethyltetrahydrophthalic acid, endomethylene hexahydrophthalic acid, naphthalenetetracarboxylic acid, diphenolic acid, trimellitic acid, pyromellitic acid, trimesic acid, cyclopentanedicarboxylic acid, 3,3 ′, 4,
4'-benzophenonetetracarboxylic acid, 1,2,3
4-butanetetracarboxylic acid, 2,2-bis (4-carboxyphenyl) propane, diimidecarboxylic acid obtained from trimellitic anhydride and 4,4-diaminophenylmethane, tris (β-carboxyethyl) isocyanurate, Isocyanurate ring-containing polyimide carboxylic acid, tolylene diisocyanate, isocyanate ring-containing polyimide carboxylic acid obtained from trimerization reactant and trimellitic anhydride of tolylene diisocyanate or isophorone diisocyanate, and the like, and one or more of these. Is used.

Of these, the use of a crosslinking component such as a trivalent or higher polyhydric carboxylic acid or polyhydric alcohol may be preferable in terms of stability such as fixing strength and offset resistance. Polyester resin obtained from these raw materials,
It can be manufactured by a usual method. Further, the glass transition temperature is preferably set in the range of 40 ° C to 80 ° C, particularly preferably in the range of 50 ° C to 70 ° C. Further, two or more kinds of the above polyester resins may be combined, and further another resin may be combined. Other resins include styrene resin, acrylic resin, styrene / acrylic resin, silicone resin, epoxy resin, diene resin, phenol resin, terpene resin, coumarin resin, amide resin, amide imide resin, butyral resin, urethane resin, ethylene And vinyl acetate resin. In the present invention, it is preferable that the polyester resin is a main component and the other resin is contained in the toner in an amount of 0 to 30% by weight.

As the coloring agent, known organic or inorganic pigments and dyes, and oil-soluble dyes can be used. For example, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 12
2, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 12,
C. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3, Lamp Black (CI No. 7
7266), Rose Bengal (CI No. 4543)
2), carbon black, nigrosine dye (CIN)
o. 50415B), metal complex salt dyes, derivatives of metal complex salt dyes, and mixtures thereof. Further, various metal oxides such as silica, aluminum oxide, magnetite and various ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide, and magnesium oxide, and a suitable mixture thereof. can give. These colorants need to be contained in a sufficient ratio to form a visible image having a sufficient density, and depend on the toner particle size and the development amount.
A ratio of about 1 to 10 parts by weight to 00 parts by weight is appropriate.

Examples of the charge controlling agent include metal salts of benzoic acid, metal salts of salicylic acid, metal salts of alkyl salicylic acid, metal salts of catechol, metal-containing bisazo dyes, tetraphenylborate derivatives, and the like, which are used in powder toners. Compounds selected from the group consisting of quaternary ammonium salts and alkylpyridinium salts, and those suitably combined, can be preferably used. The addition amount of these charge control agents to the toner is generally in the range of 0.1% by weight to 10% by weight, more preferably 0.5% to 8% by weight.
If the amount is less than 0.1% by weight, the charge control effect is insufficient,
On the other hand, if it exceeds 10% by weight, the toner resistance becomes excessively low and it becomes difficult to use the toner.

Further, the charge control agent is previously dissolved in a solvent (for example, ethyl acetate or the like) slightly soluble in a liquid (for example, water) which does not dissolve the toner substance, It is added to a solvent together with the substance, dispersed and dissolved, and the obtained mixture is mixed with a liquid that does not dissolve the toner substance (for example, a substance obtained by dissolving the toner substance in toluene), and the toner substance is formed into droplets. When the toner is manufactured by dispersing and coagulating as spherical particles by removing the solvent from the formed droplets, the charge control agent concentrates in the vicinity of the toner surface. It can be reduced to about 10 to 1/1000. Also, since the charge amount distribution becomes sharp,
This method is suitable as a method for producing the toner used in the present invention.

In the case of fixing by suppressing oil application to a fixing machine, it is preferable to add a release agent such as a wax component to the toner. As the wax component, for example, waxes and waxes include carnauba wax, vegetable wax such as cotton wax and wood wax, beeswax, animal wax such as lanolin, ozokerite, mineral wax such as celsin, and paraffin; Microcrystalline,
Petroleum wax such as petrolatum can be used. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, fatty acid amides such as 12-hydroxystearic amide, stearic amide, phthalic anhydride, and chlorinated hydrocarbons, esters, and ketones And synthetic waxes such as ethers. The amount of the release agent added to the toner is generally 1% by weight to 15% by weight, more preferably 2% by weight.
In the range of 10 to 10% by weight. If the amount is less than 1% by weight, the releasing effect is insufficient, and if the amount is more than 15% by weight, the toner fluidity is reduced and it becomes difficult to use.

Further, in order to fix at a low temperature, a wax material having a low melting point is used.
When the toner is produced by the kneading and pulverizing method, the low melting point wax is unevenly distributed on the surface of the toner, so that there are problems such as extreme decrease in fluidity and filming on the electrostatic latent image holding member.
Therefore, in that case, the toner material containing the dissolved low melting point wax is mixed with a liquid that does not dissolve the toner material, the toner material is dispersed as droplets, and the solvent is removed from the droplets to coagulate as spherical particles. A method for producing a toner (solution suspension toner) is suitable. This is because a toner in which the low-melting-point wax hardly exists on the toner surface can be obtained. Thereby, high development efficiency can be achieved with relatively low electric field peel strength.

The external additive is further added to spherical toner particles (solution suspension toner) having a relatively small surface area by adding fine particles having a particle diameter of 20 nm to 80 nm, the surface of which is treated with a hydrophobizing agent. High development efficiency can be achieved with low electric field peel strength. This is due to the fact that the probability of the toner particle surface directly touching the carrier surface is reduced, and the use of a relatively large external additive reduces the electric field peel strength to 1.0 × 10 4.
This is because high development efficiency can be achieved at ⁶ V / m or less.

In the measurement of the electric field peel strength, a developer layer is formed by supplying 10 to 30 mg / cm ² of the developer onto the developer carrier 2, and the sample is adjusted to the curvature of the developer carrier 2. And by measuring the weight of toner adhering to the aluminum electrode while stepwise applying an external electric field in a vacuum state of about 10 millTorr with an aluminum electrode provided with a gap of 400 μm, and The electric field when 50% of the weight of the toner in the developer on the developer carrier 2 moves to the aluminum electrode is expressed as electric field peel strength.

When the particle diameter of the external additive fine particles is 20 nm or less, the external additive fine particles are easily embedded in the toner, so that the function as a spacer is not sufficient. If it is 80 nm or more, the contact area with the toner particles is the same order, and the effect of reducing the contact area by the external additive fine particles cannot be sufficiently obtained. Therefore, the above range is preferable.

In the present invention, the external additive fine particles are desirably added so that the surface coverage of the toner becomes 50% or more. If the surface coverage is lower than 50%, the effect of adding the external additive fine particles cannot be sufficiently exerted. The surface coverage is defined by the following equation. f = ((3) ^1/2 / 2π) × (dt · Pt / da · P
a) × C (where f is the surface coverage, dt is the particle size of the toner, Pt
Is the specific gravity of the toner, da is the particle size of the external additive fine particles, Pa is the specific gravity of the external additive fine particles, and C is the weight ratio of the external additive fine particles / toner.

Further, as the external additive fine particles, it is desirable to use silicon oxide particles whose surface has been subjected to a hydrophobic treatment with hexamethylene disilazane or the like. The reason is,
This is because sufficient external hydrophobicity is imparted to the external additive fine particles so that the development efficiency does not decrease even under high temperature and high humidity conditions.

In the present invention, the magnetic carrier 4 has a particle diameter of 20 to 50 μm and a saturation magnetization of 30 to 70 emu.
/ G, and a magnetic carrier having a specific resistance ≧ 10 ¹⁴ Ωcm is desirable. When the particle diameter is 20 μm or less, the toner is frequently developed on the electrostatic latent image holding member due to a small magnetic force. When the thickness is 50 μm or more, charge is easily injected from the electrostatic latent image, so that development on the electrostatic latent image holding member frequently occurs. If the saturation magnetization is 30 emu / g or less, the magnetic force is so small that the toner is frequently developed on the electrostatic latent image holding member. On the other hand, at 70 emu / g or more, the adhesion between the carrier particles becomes too large, the adhesion of the external additive to the toner surface becomes too strong, and the external additive is easily embedded in the toner. Therefore, the function as the spacer is not sufficient. Disappears. The specific resistance is desirably ≧ 10 ¹⁴ Ωcm. The reason for this is that if the resistivity is 10 ¹⁴ Ωcm or less, charge is easily injected from the electrostatic latent image, so that the image is developed on the electrostatic latent image holding member. This happens frequently.

The magnetic carrier material may be a material which is strongly magnetized by a magnetic field as a core material, for example, iron, ferrite, magnetite and other metals such as iron, nickel and cobalt, manganese-copper-aluminum, manganese-manganese.
Alloys such as copper-tin, nickel, manganese, magnesium,
Spinel-type ferrites such as lithium, copper and zinc are used, and those having a particle diameter adjusted to 20 to 50 μm by classification are used.

On the surface of the core material, a coating layer is formed by coating the following various resins by heat melting or dissolving in a solvent, and the specific resistance value is set high. For forming the coating layer, for example, polyester resin, styrene resin, acrylic resin, styrene / acrylic resin, silicone resin, epoxy resin, diene resin, phenol resin, polyamide resin, polyimide resin, melamine resin,
Urea resin, fluorine resin, polyurethane resin, polycarbonate resin and the like are used. Furthermore, a so-called charge control agent can be added to the film layer. For example, as a charge control agent that can be used, a metal salt of benzoic acid, a metal salt of salicylic acid, a metal salt of alkyl salicylic acid, a metal salt of catechol, a metal-containing bisazo dye, a tetraphenylborate derivative, a quaternary ammonium salt, an alkylpyridinium Compounds selected from the group consisting of salts, and further suitable and combinations thereof can be used, but the reason is not clear, but it is necessary to coat a part of the surface of the magnetic carrier with a polymethyl methacrylate resin. Thus, polymethyl methacrylate resin is the most desirable carrier coating material because the charging property is stabilized by this.

FIG. 2 is a schematic diagram showing a state in which the toner 6 in the hopper 5 of FIG. 1 is supplied to the magnetic carrier 4 on the surface of the mixing and stirring member 3. As described above, the non-magnetic toner 6
Is placed in the hoppers 5a and 5b and is 10 mm
A magnetic carrier 4 of about 60 g / m ^{2 and} a particle size of about 50 μm is placed in a φ sleeve 3 b on a magnet roll 3 a (mixing and stirring member 3) containing a permanent magnet having a magnetic force of 41 mT and 12 poles. As a result, the magnetic carriers 4 having a thickness of about 50 to 100 μm can be formed. 120r permanent magnet
The magnetic carrier 4 is spun on the fixed sleeve by the alternating magnetic field generated by the rotation of the magnet roll by rotating the magnetic carrier 4 at pm, and the magnetic carrier 4 is passed between the sealing members 7b planted at the end of the hopper 5b. The magnetic carrier continues the spinning motion while being in contact with the non-magnetic toner 6 and the sealing material 7 at the center of the hopper 5a while the non-magnetic toner 6 is wound around.
Pass between a. When the chargeability is evaluated, the developer (a mixture of the nonmagnetic toner 6 and the magnetic carrier 4) in this portion may be sampled to measure the charge amount and the nonmagnetic toner concentration.

It should be noted that the sealing members 7b and 7a which have been planted at the hopper end 5b and the hopper center 5a.
Is made by forming conductive nylon fibers having a thickness of about 10 μm at the end of the hopper 5b and the center of the hopper 5a by electrostatic flocking. The flocking density is set in such a range that the magnetic carrier 4 can pass through but the non-magnetic toner 6 does not leak. Here, about 1 × 10 ^{2 to} 5 × 10 ³ wires /
Hair transplanted to about ² mm2. Other fibers include cotton, wool, rayon, polyester, acetate, metal fibers,
Glass fibers and the like can be used, and natural fibers and chemical fibers can be used. Flocking density is 1 × 10 ² / mm
^If it is lower than ^{2, the} nonmagnetic toner 6 leaks out of the hopper 5, which is not preferable. If the density is higher than 5 × 10 ³ / mm ² , the magnetic carrier 4 is difficult to pass, and the non-magnetic toner 6 mixed with the magnetic carrier 4 is scraped off by the sealing material 7 on which the hairs are planted. It is not preferable.
Further, if the thickness of the fiber is extremely larger than the size of the non-magnetic toner 6, the magnetic carrier 4 cannot pass easily.
This is not preferable because the non-magnetic toner 6 leaks out.

Then, the magnetic carrier 4 reaches the contact portion Y of the developer carrier 2 by the alternating magnetic field generated by the rotation of the magnet roll. When the charging property is evaluated, the reference position, the position rotated by ４, the position rotated by １ ／, and the position immediately after the contact of the sealing member 7a at the center of the hopper 5a with the mixing and stirring member 3 are determined. The developer (the mixture of the non-magnetic toner 6 and the magnetic carrier 4) at the position immediately before the sealing material 7 b at the end of the hopper 5 b is in contact with the mixing and stirring member 3 is sampled, and the charge amount and the non-magnetic toner 6 are mixed. The density is measured and used as an index of triboelectric charging of the developer.

The gap between the developer carrier 2 and the mixing and stirring member 3 is about 70 to 120 μm, but may be wider than this. The gap between the mixing and stirring member 3 and the lower part of the hopper 5 is about 200 to 500 μm, but may be wider than this.

The non-magnetic toner 6 has a sufficient charge amount and a uniform toner concentration from immediately after passing through the sealing material 7a at the center of the hopper 5a until reaching the contact portion Y of the developer carrier 2. If it is not sufficient, fogging will occur in the non-image area, and uneven density will occur in the solid area. If the toner concentration becomes extremely non-uniform, the carrier is developed on a solid portion, so that a so-called white spot may occur.

In the present invention, the electric field peeling strength at which 50% of the non-magnetic toner moves from the developer on the developer carrying member is set to 1.0 × 10 ⁶ V / m or less, and the developer on the mixing and stirring member is controlled. And the toner charge amount (Q _Y ) of the developer in the region where the triboelectrically charged developer is supplied from the mixing and stirring member to the developer carrier is set to | 15 μc.
/ G | ≦ Q _Y ≦ | 30 μc / g | For this purpose, the above range may be set by adjusting the amount of the external additive added, adjusting the amount of the magnetic carrier used, or adjusting the type and amount of the charge control agent.

In the above situation, the results of detailed observations using various developers are shown in Tables 1 to 5 relating to Examples described later. From the results, it was found that the electric field peel strength was 1.0 × 1
0 ⁶ V / m or less, and the amount of developer
5 mm or less, and the toner charge amount (Q) due to friction in a region where the developer carrier 2 and the mixing and stirring member 3 intersect.
_By setting _Y ) in the range of | 15 μc / g | ≦ Q _Y ≦ | 30 μc / g |, it is understood that a clear image without fog can be obtained.

In the present invention, it is necessary that the amount of developer ears be 0.15 mm or less. The reason is that if the amount of developer ears is made larger than this, the non-magnetic toner When the magnetic carrier 4 leaks out or the magnetic carrier 4 cannot pass through the sealing material 7 and accumulates inside and outside the hopper, and when the amount of spikes is larger than 0.15 mm, the root of the chain of the magnetic carrier 4 and the spikes This is because the movements are different, and there are problems such as generation of a toner cloud and uneven toner concentration.

For the developer sufficiently charged on the surface of the mixing and stirring member, for example, magnetic poles having different polarities are alternately arranged around the entire circumference and are arranged at intervals of 50 μm. , Roll diameter φ10 mm set to a magnetic flux density of 40 mT, roll rotation speed 120 m
The magnetic carrier 4 is carried by the spinning motion of the magnetic carrier 4 onto the m / sec developer carrier 2, and almost all the developer is captured by the magnetic field on the developer carrier to form a developer layer.

On the other hand, an electrostatic latent image of, for example, a background portion of −600 V and an image portion of −100 V is formed on the electrostatic latent image holding member 1.
0V, frequency 6 as an AC component to increase development efficiency
A non-magnetic toner 6 is applied to the electrostatic latent image of -100 V in the image area by applying a peak-to-peak voltage of 1.5 kV with a rectangular wave of kHz, and the development is completed. The gap between the electrostatic latent image holder 1 and the developer carrier 2 is set to, for example, 200 μm, but can be changed as appropriate. After the development, the magnetic carrier 4 on the developer carrier 2 is returned to the surface of the mixing and stirring member 3 by the rotation of the developer carrier 2, and is sent to the hopper 5 again by the spin motion of the magnetic carrier 4, and The toner is mixed with the non-magnetic toner 6 and used again for development.

[0040]

Embodiments of the present invention will be described below with reference to the drawings. Parts mean parts by weight. Embodiment 1 FIG. 3 shows an example of a developing device for performing the image forming method of the present invention. In FIG. 3, reference numeral 16 denotes a non-magnetic toner. The stirring and mixing member is a fixed sleeve 13
b and a rotating magnet roll 13 containing a permanent magnet
a. The non-magnetic toner 16 is charged into the hoppers 15a and 15b, and the magnetic carrier 1 is placed on a magnet roll including a permanent magnet in a sleeve.
4, the nonmagnetic toner is supplied to the magnetic carrier 14 on the sleeve by rotation of the permanent magnet, the sleeve, or both, and the magnetic carrier is spun by the alternating magnetic field. In the meantime, stirring and mixing and triboelectric charging are performed. The sealing members 17a and 17b come into contact with the mixing and stirring member.

In the 10 mmφ sleeve 13b, a magnetic force 41
When a magnetic carrier 14 having a particle diameter of about 60 g / m ^{2 and} a diameter of about 50 μm is placed on a magnet roll 13 a containing a permanent magnet having 6 poles at mT, a magnetic carrier 14 having a layer thickness of about 50 to 100 μm is obtained. You can stand ears. By fixing the sleeve and rotating the permanent magnet of the magnet roll at 120 rpm, the alternating magnetic field generated by the rotation of the magnet roll spins the magnetic carrier 14 on the sleeve, and the sealing material implanted at the end of the hopper 15b. 17b. The magnetic carrier 14 continues spinning while being in contact with the supplied non-magnetic toner 16, and passes between the seal members 17 a at the center of the hopper 15 a with the non-magnetic toner 16 being wound. In addition, as for the sealing materials 17b and 17a in which the flocking at the end portion of the hopper 15b and the central portion of the hopper 15a, conductive nylon fibers having a thickness of about 10 μm were formed by electrostatic flocking at the end portion of the hopper 15b and the central portion of the hopper 15a. Things.
The flocking density is set in such a range that the magnetic carrier 14 can pass through but the non-magnetic toner 16 does not leak. In this embodiment, the hairs are planted at about 1 × 10 ³ fibers / mm ² .

Then, the magnetic carrier 14 reaches the contact portion Y of the developer carrier 12 by the alternating magnetic field generated by the rotation of the magnet roll. The gap between the developer carrier 12 and the sleeve 13b of the mixing and stirring member is 100 μm. The gap between the sleeve 13b of the mixing and stirring member and the lower part of the hoppers 15a and 15b is 200 μm. The amount of ears of the developer (mm): d is about 0.10
mm is adjusted by the application amount of the magnetic carrier 14 (approximately 50 μm of approximately 60 g / m ² on the sleeve 13b).
m of magnetic carriers 14 are placed. ). The developer sufficiently charged on the surface of the mixing and stirring member is 100 μm.
The developer is captured on the developer carrier 12 provided with a gap of m. That is, magnetic poles having different polarities are alternately arranged over the entire circumference, and the interval is set to 150 μm, and the magnetic flux density 2
The magnetic carrier 14 is carried by the spin motion of the magnetic carrier 14 onto the developer carrier 12 having a roll diameter of 10 mm and a roll rotation speed of 120 mm / sec set at 5 mT, and almost all the developer is captured by the magnetic field on the developer carrier. Thus, a developer layer is formed.

The electrostatic latent image holding member 11 has a background portion -600.
V, an image latent image of -100 V is formed, and a DC component of -500 V and an AC component for increasing the development efficiency are applied to the developer carrier 12 from the outside at a frequency of 6 kV.
With a rectangular wave of Hz, a peak-to-peak voltage of 1.5 kV is applied. Image portion of electrostatic latent image on electrostatic latent image holding member-100 V
, And the development is completed. The gap between the electrostatic latent image holder 11 and the developer carrier 12 is 20
It is 0 μm. Then, the magnetic carrier 14 on the developer carrier 12 that has completed the development is returned to the surface of the mixing and stirring member by the rotation of the developer carrier 12, and the magnetic carrier 1
4 is again sent to the hoppers 15a and 15b by the spinning motion and mixed with the non-magnetic toner 16 in the hopper,
Used again for development.

The developer used in the above-mentioned developing method was produced by the following method. (I) Preparation of Non-magnetic Toner (A) Preparation of Pigment Dispersion Polyester resin having ethylene oxide adduct of bisphenol A and terephthalic acid as a skeleton: 50 parts (Tg: 65 ° C., softening point: 102 ° C., weight average molecular weight) : 9000) Copper phthalocyanine pigment 50 parts (CI Pigment Blue 15: 3, trade name: Cyanine Blue 4933M, manufactured by Dainichi Seika Co., Ltd.) 100 parts of ethyl acetate Glass beads were added to the dispersion of the above material composition, and the mixture was added to a sand mill disperser. I attached it. While cooling around the dispersion container, the mixture was dispersed in a high-speed stirring mode for 3 hours to prepare a pigment dispersion having a pigment concentration of 10% by weight.

(B) Preparation of Micronized Wax Dispersion Paraffin Wax (Melting Point: 85 ° C., Latent Heat of Melting: 193 mJ / mg) 15 Parts Toluene 85 Parts Agitating blades are attached to the above materials, and a heating medium is circulated around the container. It was put into a dispersing machine with a function to make it work. The temperature was gradually increased while stirring at 83 revolutions per minute, and finally the mixture was stirred for 3 hours while maintaining the temperature at 100 ° C. Next, the mixture was cooled to room temperature at a rate of about 2 ° C. per minute while stirring was continued to precipitate wax in the form of fine particles. Laser diffraction / scattering particle size distribution analyzer LA
The average particle size of the wax was measured using -700 (manufactured by Horiba, Ltd.) and found to be about 0.85 μm. The dispersion liquid of the micronized wax thus prepared was diluted with ethyl acetate so that the weight concentration of the wax became 15% by weight.

(C) Preparation of Toner Oil Phase Polyester resin having ethylene oxide adduct of bisphenol A and terephthalic acid as a skeleton (Tg: 65 ° C., softening point: 102 ° C., weight average molecular weight: 9000) 85 parts Pigment dispersion (Pigment concentration 10% by weight) 50 parts Dispersion of micronized wax (wax concentration 15% by weight) 33 parts Ethyl acetate 32 parts The oil phase component of the above material composition is put into a homomixer (Ace Homogenizer, manufactured by Nippon Seiki Co., Ltd.). And 15000 per minute
The mixture was stirred for 2 minutes on a rotation to prepare a homogeneous oil phase.

(D) Preparation of Aqueous Phase 60 parts of calcium carbonate (average particle diameter 0.03 μm) 40 parts of pure water The above material was stirred in a ball mill for 4 days. When the average particle diameter of calcium carbonate was measured using the above-mentioned laser diffraction / scattering particle size distribution analyzer LA-700 (manufactured by Horiba, Ltd.), it was found to be about 0.02 μm. on the other hand,
A 2% by weight aqueous solution of carboxymethyl cellulose (Cellogen BSH, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was separately prepared.

(E) Preparation of Toner Oil phase 60 parts Calcium carbonate aqueous solution 10 parts Carboxymethylcellulose aqueous solution 30 parts The above-mentioned materials were charged into a colloid mill (manufactured by Nippon Seiki Co., Ltd.), and the gap was 1.5 mm, and the rotation speed was 8,000 rpm. The emulsification was performed for a minute. Next, the obtained emulsion was put into a rotary evaporator, and the solvent was removed under reduced pressure of 30 mmHg at room temperature for 3 hours. Thereafter, 12N hydrochloric acid was added until the pH reached 2, and calcium carbonate was removed from the toner surface. Thereafter, centrifugal sedimentation was performed, and the supernatant was exchanged three times and washed, and then dried to take out the toner. The average particle size of the toner is 7.0 μm, and the GSD which is an index of the particle size distribution is 1.22.
(The volume average particle diameter, that the square root of d84 / d16), the sphericity is 110-118, the shape created a good toner particles T ₁ at approximately spherical.

Further, the mixture was kneaded, crushed and classified with the same composition to obtain an irregular toner (average particle diameter of the toner is 7.0 μm and GSD which is an index of the particle size distribution is 1.22).
1) The toner particles T ₂ (Comparative Example) and the toner particles T
₂ into a spray drier, instantaneously heat it and make it spheroidized by the surface tension.
The toner particles T ₃ spherical 0 was prepared.

The toner composition is a polyester resin having a skeleton of ethylene oxide adduct of bisphenol A and terephthalic acid (Tg: 65 ° C., softening point: 102 ° C.,
85 parts by weight average molecular weight: 9000), 5 parts by weight of a copper phthalocyanine pigment (CI Pigment Blue 15: 3, trade name: Cyanine Blue 4933M; manufactured by Dainichi Seika Co., Ltd.), paraffin wax (melting point: 85 ° C., latent heat of fusion: 193 mJ / m)
g) 5 parts.

Further, instead of the polyester resin used in the preparation of the pigment dispersion (A), a styrene / n-butyl acrylate copolymer resin (SBM1 manufactured by Sanyo Chemical Co., Ltd.)
00 (Tg = 42 ° C., Mw = 14800)) 50 parts and Spiron Black TRH (Hodogaya Chemical Co., Ltd.) 0 parts, 0.1 part
Parts, 0.2 parts, 0.5 parts, 1.0 parts, 2.0 parts, 5.0 parts
Parts and 10 parts were previously prepared in the same manner using a kneader, and the average particle diameter was 7.0 μm, the GSD as an index of particle size distribution was 1.25 ± 0.05, and the degree of sphericity was 110 to 120, the toner particles T ₄ to have a substantially spherical shape.
To prepare a T _11.

(II) Addition of External Additives Silicon oxide particles having an average particle diameter of 30 to 40 nm, which has been hydrophobized with hexamethylene disilazane, and having a range of 20 nm to 80 nm (Trefil F-100, manufactured by Toray Industries, Inc.)
With a Henschel mixer type mixer
At 120 msec, 1.0% by weight was attached to all the toner particle surfaces at 0 m / sec.

(III) Preparation of Magnetic Carrier Using 100 parts of F35 (Cu-Zn ferrite: Powder Tech) as a carrier core, and coating with 3.5 parts of polymethyl methacrylate using a heating kneader to prepare a carrier, Sieve through 10μm, 15μ particle size
Magnetic carrier particles of m, 20 μm, 50 μm, and 60 μm: X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ were collected. The specific resistance of these magnetic carriers is 1.5 to 3.2 × 10 ¹⁵ Ω.
cm and saturation magnetization of 55 emu / g.

Further, as a comparative magnetic carrier, a carrier was prepared by coating with 1.0 part and 2.5 parts of polymethyl methacrylate, and sieved to collect magnetic carrier particles having a particle diameter of 50 μm. The specific resistance of the magnetic carrier particles is 1.0 × 10 ⁸ Ωcm (Y ₁ ), 4.2 × 10
^{It was 12} Ωcm (Y ₂ ).

Further, by changing the composition ratio of the carrier core, the value of the saturation magnetization was set to 20 emu / g, 30 emu / g,
Those having been changed to 70 emu / g and 80 emu / g were similarly coated with 3.5 parts of polymethyl methacrylate to have a specific resistance of 1.5 to 3.2 × 10 ¹⁵ Ωcm,
The particles were sieved to produce magnetic carrier particles having a particle diameter of 50 μm, which were designated as Z _{1 to} Z ₄ .

On the other hand, 0.1 part, 0.2 part, 0.5 part, and 1 part of a nigrosine dye were added to 3.5 parts of polymethyl methacrylate.
Then, the carrier core was coated to prepare magnetic carrier particles having a particle diameter of 50 μm, which were designated as W _{1 to} W ₄ .

The magnetic carrier and the non-magnetic toner described above are used in FIG.
The test was conducted in the developing device described in the above section. Table 1 shows the developer, the developing conditions, and the results of the test. The test was performed under the following conditions. Photoconductor: OPC (organic photoconductor) (φ24 mm) ROS LED (600 dpi) Process speed: 120 mm / s Latent image potential: background portion = −600 V, image portion = −100 V Developer carrier: conductive substrate: stainless steel , Φ10 mm Magnetic recording layer: Fe ₃ O ₄ dispersed in polyurethane (film thickness 50 μm) Magnetic pole width: 50 μm Magnetic flux density: 40 mT Magnetic pole interval: 50 μm Circular speed: 140 mm / s Photoconductor drum and developer carrier Gap: 200 μm Development bias: −500 VDC + 1500 Vpp (6K
Hz) Print test environment: 22 ° C, 55% RH

The evaluation results were measured by the following methods. Measurement of toner charge amount (Q _Y ): contact portion Y with developer carrier 12 and hopper inlet portion Z on mixing and stirring member
Was measured by a blow-off method. The values at the initial stage, after printing 1,000 sheets, and after printing 20,000 sheets are shown. Amount of ear of developer: The ear of developer was observed with an optical microscope. The focus of the light microscope was determined from the depth position of the head and root of the ear.

Density reproduction: reflection densitometer (X-Rite40)
4, the solid part was measured by X-Rite, U.S.A.), and the reflection density of 1.4 or more was evaluated as ○, 1.2 to 1.4 as Δ,
1.2 or less was evaluated as x. The values at the initial stage, after printing 1,000 sheets, and after printing 20,000 sheets are shown. Background fog: A background portion on the surface of the photoreceptor after development is transferred with a mending tape, attached to a white sheet of paper, and used as a reflection densitometer (X-Rite404, US X-Rite).
X) when the reflection density was 0.01 or more at the fog at the ground fog, Δ when it was visible but not detectable with a reflection densitometer, and ○ when it was not visible. . Initial, after printing 1000 sheets and 200
Shows the value after printing 00 sheets.

State of carrier adhesion to photoreceptor: A solid portion of 10 cm ^{2 on} the photoreceptor surface after development was observed with an optical microscope, and the number of carriers adhering to the solid portion was examined. In the case where there was no sample, ○ was set for 1 to 10 pieces, and X was set for 10 pieces or more. Generation of toner cloud: After setting up a cloud catch pan under the developing machine and printing 1000 sheets, the amount of cloud toner accumulated in this was measured and the weight was measured for 1 mg or less. X.

[0061]

[Table 1]

According to Experiments # 1, 2, 3, 5, and 6, it was found that the amount of spikes of the developer was set to 0.15 mm or less, so that there was no toner cloud and a good charge amount was obtained.
It can be seen that a clear print image can be obtained. Experiment # 3
From 1, 32, and 4, it can be seen that it is desirable from the viewpoint of density reproduction that the shape of the toner is spherical.

From the experiments # 3, 33 and 34, the specific resistance of the carrier was ≧ 10 ¹⁵ Ωcm, and the experiments # 3, 20, 21, 22 and
23, the carrier magnetization characteristics (saturation magnetization at 1000
Oe) is in the range of 30-70 emu / g;
From 5, 36, 37, 38, the particle size of the carrier is from 20 to 5
It can be seen that a range of 0 μm is desirable. Further, the number of prints was increased to 50,000 under the conditions of Experiments # 3 and # 32.
When the test was advanced to 0 pv, it was found that in Experiment # 3, almost the initial image density was maintained, whereas in Experiment # 32, the image density was less than 1.0.
From this result, as a non-magnetic toner, a toner substance dispersed and dissolved in a solvent is mixed with a liquid that does not dissolve the toner substance, dispersed as droplets, and spherical particles are formed by removing the solvent from the droplets. It turns out that it is desirable to use what was manufactured by solidification. On the other hand, Experiment # 3,
From 12 to 19, it is desirable that the binder used for the toner is a polyester resin, which is strongly negatively charged. However, if a charge control agent is added to a styrene / acrylic resin, the toner charge amount (Q _Y ) due to friction is | 15 μc / g. | ≦ Q _Y ≦ | 30 μc /
g |, which indicates that a good print image can be obtained.

[0064] Instead of T ₄ toners of Example 1, a solution obtained by previously dissolving a charge control agent in a solvent to slightly soluble in the liquid which does not dissolve the toner materials, solvent together with other toner materials The resulting mixture was mixed with a liquid that does not dissolve the toner substance, dispersed as liquid droplets, and the solvent was removed from the liquid droplets to coagulate as spherical particles.

For example, at the time of preparing the non-magnetic toner 16 in Example 1, methyl ethyl ketone 1 was used as a solvent that was slightly dissolved in a liquid in which the toner substance was not dissolved in advance.
(A) were prepared by dispersing 1 part, 2 parts, 5 parts and 10 parts of a solution obtained by previously dispersing 00 parts and 2 parts of a charge controlling agent (Bontron E-81, manufactured by Orient Chemical Co., Ltd.) for 24 hours using a ball mill. in addition to the preparation of the pigment dispersion, to prepare a toner in the same manner as the T ₄ toner produced. These toners T ₁₂ , T
₁₃ , T ₁₄ , and T ₁₅ were evaluated in the same manner as in Example 1. Table 2 shows the developer and developing conditions, and Table 3 shows the test results.

[0066]

[Table 2]

[0067]

[Table 3] As is clear from Tables 2 and 3, by using the toner obtained by the above-described method, the chargeability is high and stable even in a summer environment.

Example 3 In place of T ₄ in Example 1, the amount of an external additive (Trefil F-
100, manufactured by Toray Industries, Inc.) 0% by weight (T ₁₅ ), 0.3% by weight
(T _14), 0.5 wt% (T _13), 1.5 wt%
The toner particles changed to (T ₁₂ ) and a toner in which 0.5% by weight (T ₁₆ ) of an external additive (Trefil F-100, manufactured by Toray Industries, Inc.) was added instead of T ₄ were produced and tested. Tested as in Example 1. Table 4 shows the developer and developing conditions, and Table 5 shows the test results.

[0069]

[Table 4]

[0070]

[Table 5] As is clear from Tables 4 and 5, the electric field peel strength (×
It can be seen that when (10 ⁶ V / m) exceeds 1.0, the density reproduction deteriorates.

Example 4 As shown in FIG. 3, flocked sealing materials 17a and 17b were provided at the center of the hopper 15a and at the end of the hopper 15b. The magnetic carrier 14 on the sleeve is spun by the alternating magnetic field generated by the rotation of the magnet roll, and passes between the sealing members 17b planted at the hopper end 15b, and the spinning motion is performed while contacting the non-magnetic toner 16. Continuously, the hopper 15 a
It passed between the sealing members 17a at the center. In that case,
The non-magnetic toner 16 did not fall out of the hopper. The center of the hopper 15a and the hopper 1
The sealing materials 17a and 17b at the end of the 5b are formed by forming conductive nylon fibers having a thickness of about 10 μm at the center of the hopper 15a and at the end of the hopper 15b by electrostatic flocking. The flocking density is set in such a range that the magnetic carrier 14 can pass through but the non-magnetic toner 16 does not leak. Here, the hairs were implanted at about 1 × 10 ³ fibers / mm ² .

As a comparison, the flocked sealing material 17a,
In the hopper without 17b, the non-magnetic toner 16 was slightly spilled out while passing between the central portions of the hopper 15a while the non-magnetic toner 16 was being wound.
In this case, the distance between the stirring / mixing member composed of the magnet roll and the sleeve and the hopper was about 50 μm.

Example 5 In place of T ₆ in Example 1, P-5 was used as a charge controlling agent.
1 using (manufactured by Orient Chemical Industries, Ltd.), the amount to change the prototyped toner was tested in the same manner as in Example 1 in combination with a carrier X _4. As a result, it was found that good print images could be obtained by setting the frictional charging property of the developer to | 15 μc / g | ≦ QY ≦ | 30 μc / g |. The test conditions were as follows. Photoconductor: OPC (φ24 mm) Process speed: 120 mm / s Latent image potential: background portion = 100 V, image portion = 600 V Developer carrier: conductive substrate: stainless steel φ10 mm Magnetic recording layer: Fe ₃ O ₄ dispersed in polyurethane What has been made (film thickness 50 μm) Magnetic pole width: 50 μm Magnetic flux density: 40 mT Magnetic pole interval: 50 μm Circumferential speed: 140 mm / s Gap between photosensitive drum and developer carrier: 200 μm Development bias: 200 VDC + 1500 Vpp (6 KH)
z)

[0074]

As described above, according to the image forming method of the present invention, 50% of the non-magnetic toner is removed from the developer on the developer carrier.
By moving the electric field peeling strength, the amount of developer spikes on the mixing / stirring member, and the toner charge amount of the developer in the region supplied from the mixing / stirring member to the developer carrier, by setting the specific range described above. , Can be adapted to color, complex configuration,
With no need for control, a small and simple developing device can provide a copy image of stable image quality over a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of a developing device used in an image forming method of the present invention.

FIG. 2 is an enlarged view around a stirring and mixing member in FIG.

FIG. 3 is a schematic configuration diagram of an example of a developing device used in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrostatic latent image holder, 2 ... Developer carrier, 3 ... Stirring / mixing member, 3a ... Magnet roll, 3b ... Sleeve, 4
... magnetic carrier, 5, 5a, 5b ... hopper, 6 ... non-magnetic toner, 7a, 7b ... sealing material, 11 ... electrostatic latent image holder, 12 ... developer carrier, 13a ... magnet roll,
13b: sleeve, 14: magnetic carrier, 15a, 15
b: hopper, 16: non-magnetic toner, 17a, 17b ...
Sealing material.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Tanaka 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. Inventor Nobumasa Furuya 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd.

Claims (4)

[Claims] 1. A magnetic carrier is arranged on a mixing and stirring member comprising a sleeve and a magnet roll including a permanent magnet in the sleeve, and a non-magnetic toner is supplied to the magnetic carrier from a hopper to form a permanent magnet, a sleeve, or the like. After performing the triboelectric charging by the rotation of both, the developer is supplied onto a developer carrier in which magnetic poles having different polarities are alternately arranged over the entire circumference so that the interval between the magnetic poles is 25 μm to 250 μm. In the image forming method for developing the electrostatic latent image on the electrostatic latent image holding member, the electric field peel strength at which 50% of the non-magnetic toner moves from the developer on the developer holding member is set to 1.0 × 10 ^6. V / m or less, the amount of spikes of the developer on the mixing and stirring member is set to 0.15 mm or less, and the developer in a region where the triboelectrically charged developer is supplied from the mixing and stirring member to the developer carrier. No The toner charge amount (Q _Y ) is | 15 μc
/ G | ≦ Q _Y ≦ | 30 μc / g | 2. A toner substance dispersed and dissolved in a solvent is mixed with a liquid that does not dissolve the toner substance, dispersed as droplets, and solidified as spherical particles by removing the solvent from the droplets. 2. The image forming method according to claim 1, wherein a non-magnetic toner having a degree of spheroidization of 120 or less is used. 3. A solution in which a non-magnetic toner is prepared by previously dissolving a charge controlling agent in a solvent that is slightly soluble in a liquid that does not dissolve the toner substance, and dispersed and dissolved in the solvent together with other toner substances. 3. The method according to claim 2, wherein the mixture obtained is mixed with a liquid that does not dissolve the toner substance, dispersed as droplets, and solidified as spherical particles by removing the solvent from the droplets.
2. The image forming method according to 1., 4. A means for supplying the non-magnetic toner to the magnetic carrier on the mixing and stirring member, a hopper provided with a flocked sealing material so as to supply the non-magnetic toner to a part of the surface of the mixing and stirring member is provided. 2. The image forming method according to claim 1, wherein the non-magnetic toner is allowed to pass through the flocked sealing material while being mixed with the magnetic carrier so that the flocked sealing material is in contact with the mixing and stirring member.