JP2000258956A - Image forming method and developer used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method which does not give rise to image defects, such as fogging, degradation in image density, and degradation in image quality in spite of long-term use in a contactless development system using a magnetic one-component developer and a developer used for the same. SOLUTION: The image forming method consists in placing an electrostatic latent image holding member 1 and a developer carrying member 4 apart a specified spacing in a developing section, regulating a developer layer to a thickness thinner than the spacing described above the transporting this layer to the developer carrying member by a developer layer regulating member 11 and develops the developer layer by impressing alternating electric fields thereto in the developing section. The method described above is characterized in that the developer is at least the developer prepared by fusing at least magnetic particles and resin particles in an aqueous medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and a developer used for the method.

[0002]

2. Description of the Related Art In recent years, image forming techniques such as copying machines, printers, and facsimile machines have been remarkably developed, and the most frequently used one belongs to an electrostatic image forming method represented by an electrophotographic system. It is.

The reason is that an electrostatic image forming method such as an electrophotographic method is capable of obtaining a high-quality image at a high speed and has durability and stability that can withstand long-term use. Would. However, as the performance of related technologies such as personal computers has improved, the required performance level has been increasing year by year, and further improvement and performance improvement are required to satisfy the demand.

Further, as electrophotographic developers, there are a so-called two-component developer composed of a toner and a carrier and a magnetic one-component developer composed only of a magnetic toner. Since the image forming method of the developing method using the magnetic one-component developer does not require the use of a carrier, a stirrer for mixing the carrier and the toner is unnecessary, and the mixing ratio of the toner and the carrier is kept constant. No equipment needed. For this reason, since the developing device is simplified, there is an advantage that the entire device can be reduced in size and the like. Therefore, it is particularly suitably used as a small electrophotographic electrostatic image forming method for a so-called printer or the like. Development is being done.

For example, in this area, Japanese Patent Application Laid-Open No. 4-2844
No. 61, JP-A-5-66604 and JP-A-6-60604
And -250446. However, when this method is used, fogging or the like is generated after long use, and a solution to this problem is required.

In the so-called magnetic one-component system, unlike a two-component developer, there is no charge-imparting member for toner such as a carrier. Therefore, for example, a developer carrier (so-called developing sleeve) or a developer layer regulating member is not used. The toner itself is triboelectrically charged by the triboelectric charging and retains the electric charge. However, in a conventional so-called pulverized toner, toner and fine powder adhere to the developer carrier and the developer layer regulating member due to frictional stress between the developer carrier and the developer layer regulating member. As a result, it is presumed that a problem of lowering their charge providing ability occurs, and as a result, a problem such as fog is caused.

To solve the problem of the fine powder toner, JP-A-60-31147 and JP-A-60-107 are known.
656 and JP-A-60-117255 propose a suspension polymerization toner which is spherical and has a small particle size distribution. However, since the suspension polymerization toner is a true sphere, the toner tends to be excessively conveyed from the toner layer regulating member, and the charging property may not be sufficiently imparted in some cases. Further, since the spherical shape has strong adhesion to the photoreceptor, there is a problem that cleaning is difficult.

[0008] For this reason, it has been proposed to change the shape of the toner to a shape having irregularities on the toner surface rather than a true sphere in order to solve the above problem. Japanese Patent Application Laid-Open No. Hei 7-36207 proposes an image forming method in which the level of toner deformation is specified by a shape factor as a solution to these problems. A conventional method is disclosed in which resin particles are adhered to the surface of a suspension-polymerized toner to deform the resin, or a method in which the suspension-polymerized toner is immersed in a solvent to swell, then reduced in pressure and dried to deform the toner.

However, when the surface of the suspension-polymerized toner is deformed due to the adhesion of resin particles, the resin particles adhered to the surface may be separated from the toner surface due to frictional stress with the toner conveying member and the toner layer regulating member, or the resin particles on the surface may be dispersed. And the charge distribution tends to be broad, and the resolution of characters is degraded. Further, the toner whose surface is deformed by swelling the suspension polymerization toner by immersing it in a solvent tends to have unstable toner characteristics due to the difference between production lots and has a problem that an image is not stable.

As a result, it has not been practically possible to form a stable image over a long period of time by the magnetic one-component developing system which is a simple and useful technique.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image defect such as fogging, image density reduction and image quality reduction even in a long-term use in a non-contact development system using a magnetic one-component developer. An object of the present invention is to provide an image forming method without the above and a developer used therefor.

[0012]

The object of the present invention is achieved by any one of the following constitutions.

[1] The electrostatic latent image holding member and the developer carrying member are arranged at a predetermined gap (a) in the developing section, and the gap (a) is provided in the developer carrying member by a developer layer regulating member. a) regulating and transporting the developer layer to a thickness smaller than that of a), and applying an alternating electric field in a developing section to perform development, wherein the developer comprises at least magnetic particles and resin particles in an aqueous medium; An image forming method, which is a developer containing a toner fused in the toner.

[2] The electrostatic latent image holding member and the developer carrying member are arranged at a predetermined gap (a) in the developing section, and the gap (a) is provided between the developer carrying member and the developer layer regulating member. a) controlling the developer layer to a thickness smaller than a) and transporting the developer layer, and applying an alternating electric field in a developing unit to develop the image; An image forming method, which is a developer containing a toner fused in the toner.

[3] The electrostatic latent image holding member and the developer carrying member are arranged at a fixed gap (a) in the developing section, and the gap (a) is provided on the developer carrying member by a developer layer regulating member. a) a developer used in an image forming method in which a developer layer is regulated and transported to a thickness smaller than that of a), and an alternating electric field is applied in a developing unit to develop the image; A developer comprising a toner obtained by fusing particles with an aqueous medium.

[4] The electrostatic latent image holding member and the developer carrying member are arranged at a predetermined gap (a) in the developing section, and the gap (a) is provided between the developer carrying member and the developer layer regulating member. a) a developer used in an image forming method in which a developer layer is regulated and transported to a thickness smaller than that of a) and an alternating electric field is applied in a developing section to perform development, wherein the developer contains at least spherical magnetic particles; A developer comprising a toner obtained by fusing resin particles in an aqueous medium.

The reason why the effects of the present invention can be obtained is as follows.
Although not always clear, the inventors think as follows.

In the non-contact magnetic one-component development, the developer must be formed in a thin layer and transported to a development area. As a result, the rising characteristic of the charge amount of the developer is good, and the charge amount distribution can be made uniform. However, when the developer (also referred to as toner) formed on the developer carrying member is formed as a thin layer, and there is a developer remaining without being completely developed, the developer layer regulating member may be used. Due to repeated stress, the toner is crushed or not sufficiently replaced with new toner. In addition, when new toner is supplied and friction occurs with the toner itself, frictional charging occurs between the toners, and the occurrence of fogging occurs because the opposite polarity toner is easily generated.

The present invention has been proposed to solve this problem, and is a polymerization toner prepared in a so-called aqueous medium, wherein resin particles and magnetic particles or resin particles containing magnetic particles are mixed in an aqueous medium. It has been found that the problem of the present invention can be solved by using the toner fused by the method described above.

That is, the toner of the present invention is a method capable of maintaining a uniform surface property and making the shape irregular, and the toner using this method is used in a non-contact magnetic one-component developing system. That is.

The toner according to the present invention has fine irregularities and has uniform surface properties as a whole. The present inventors have found that by using a toner formed by fusing resin particles in an aqueous medium, the replaceability of the toner from the developer carrying member can be improved, and the present invention has been completed. Was.

The polymerization toner is prepared in one step using an aqueous medium, and unlike the conventional pulverization toner, there is no surface state formed due to breakage or the like, and a uniform surface can be obtained. In addition, a toner having a uniform charge amount and a sharp charge amount distribution can be prepared.

However, among them, since the suspension polymerization toner is a spherical toner, the charge density on the surface of the toner is increased, and the adhesion to the developer carrier is increased.
As a result, replacement of undeveloped toner becomes worse, and toner remaining on the developer carrier for a long time is generated. As a result, there is also a problem that fogging occurs due to frictional charging with new toner.

Since the toner of the present invention is made by fusing synthetic resin particles, the particle diameters are uniform, the surface has irregularities, and the charge amount (Q / M) of the toner is extremely low. It will be uniform, with no concentration of charge in the toner particles and no uneven adhesion.

On the other hand, the so-called pulverized toner which has been widely used in the past has a large variation in particle size even if classified,
Since it is difficult to make the composition of each toner uniform,
Variations in the amount of charge between toners are also large. Therefore, the adhesive force to the developer carrying member also differs between the toners, and tends to have a distribution. In particular, in the case of a pulverized toner, so-called fine powder is liable to be generated at the time of pulverization. When the fine powder having this property adheres by friction with the developer carrying member, it is extremely difficult to be separated from the developer carrying member, and a phenomenon occurs in which the powder is fused by repeated friction. As a result, a material having the same properties as the toner adheres, and the triboelectric charging property with respect to the toner is significantly reduced, resulting in a reduction in the charging property of the toner. This phenomenon causes image defects such as fog to occur. It is presumed that the influence on the developer layer regulating member also occurs.

Since the toner of the present invention is a toner fused in an aqueous medium, there is no fine powder.
It does not contain fine powder with high adhesion to the developer carrier and the developer layer regulating member, and does not contaminate them.
As a result, it is possible to maintain stable chargeability for a long period of time.

Next, the materials, requirements, devices and the like used in the present invention will be further described.

The toner used in the present invention is a toner obtained by fusing resin particles in an aqueous medium.

The resin particles containing a colorant (magnetic particles) may be produced by fusing them in an aqueous medium. However, the problem of polymerization stability when preparing resin particles containing magnetic particles, and the problem of toner From the viewpoint of stabilization in production, a toner obtained by fusing resin particles, magnetic particles, and release agent particles in an aqueous medium is more preferable. Since the toner has a shape having irregularities on the surface from the time of toner production, and furthermore, since the toner is fused in an aqueous medium, there is little difference in the shape and surface properties between the particles. Is sharp, and a finished image excellent in resolution with less toner scattering can be obtained. As described above, this will greatly contribute to the effect of the present invention.

As a method for fusing in an aqueous medium, for example, JP-A-63-186253 and JP-A-63-282749.
JP-A-4-284461 and JP-A-7-1465.
No. 83, and a method of forming a resin particle by salting out / fusion, and the like.

The resin particles used in the production of the toner of the present invention preferably have a weight average particle size of 50 to 2,000 nm. These resin particles may be formed by any of the granulation polymerization methods such as emulsion polymerization, suspension polymerization and seed polymerization. Emulsion polymerization is most preferably used in the present invention.

Hereinafter, examples of the material of the resin particles and the production method will be described.

<< Material >> [Monomer] As the polymerizable monomer, a radical polymerizable monomer is used as an essential component, and a crosslinking agent can be used if necessary. Further, it is preferable to have at least one kind of the following radical polymerizable monomers having an acidic group or the following radical polymerizable monomers having a basic group.

(1) Radical polymerizable monomer The radical polymerizable monomer component is not particularly limited, and a conventionally known radical polymerizable monomer can be used. Also, to satisfy the required characteristics,
Species or a combination of two or more can be used.

Specifically, aromatic vinyl monomers, (meth) acrylate monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers Monomers, halogenated olefin monomers and the like can be used.

As the aromatic vinyl monomer, for example,
Styrene, o-methylstyrene, m-methylstyrene,
p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n- Styrene-based monomers such as octylstyrene, pn-noelstyrene, pn-decylstyrene, pn-dodecylstyrene, 2,4-dimethylstyrene, and 3,4-dichlorostyrene, and derivatives thereof. .

(Meth) acrylic acid ester-based monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenol acrylate, methyl methacrylate, and ethyl methacrylate. Butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.

Examples of the vinyl ester monomers include vinyl acetate, vinyl propionate, vinyl benzoate and the like.

Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like.

Examples of the monoolefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene and 4-methyl-1-pentene.

Examples of the diolefin monomer include butadiene, isoprene, chloroprene and the like.

Examples of the halogenated olefin monomer include:
Vinyl chloride, vinylidene chloride, vinyl bromide and the like.

(2) Crosslinking Agent As the crosslinking agent, a radical polymerizable crosslinking agent may be added in order to improve the properties of the toner. Examples of the radical polymerizable crosslinking agent include divinylbenzene, divinylnaphthalene,
Examples thereof include those having two or more unsaturated bonds such as divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.

(3) Radical polymerizable monomer having an acidic group or radical polymerizable monomer having a basic group Radical polymerizable monomer having an acidic group or radical polymerizable monomer having a basic group For example, an amine compound such as a carboxyl group-containing monomer, a sulfonic acid group-containing monomer, a primary amine, a secondary amine, a tertiary amine, and a quaternary ammonium salt may be used. it can.

Examples of the radical polymerizable monomer having an acidic group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, and monobutyl maleate as carboxylic acid group-containing monomers. And monooctyl maleate.

Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfosuccinic acid, and octyl allyl sulfosuccinate.

These may have a structure of an alkali metal salt such as sodium or potassium or an alkaline earth metal salt such as calcium.

Examples of the radical polymerizable monomer having a basic group include amine compounds, such as dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and quaternary of the above four compounds. Ammonium salt, 3-dimethylaminophenyl acrylate, 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, piperidylacrylamide, methacrylamide, N-butylmethacrylamide, N -Octadecylacrylamide; vinylpyridine, vinylpyrrolidone; vinyl N-methylpyridinium chloride, vinyl N-ethylpyridinium chloride, N, - it can be exemplified diallyl ammonium chloride, N, the N- diallyl-ethyl chloride or the like.

As the radical polymerizable monomer used in the present invention, a radical polymerizable monomer having an acidic group or a radical polymerizable monomer having a basic group is contained in an amount of 0.1 to 15% of the whole monomer. Preferably, the radical polymerizable cross-linking agent is used in the range of 0.1 to 10% by weight, based on the total radical polymerizable monomer, depending on its properties.

[Chain transfer agent] For the purpose of adjusting the molecular weight, a commonly used chain transfer agent can be used.

The chain transfer agent is not particularly restricted but includes, for example, mercaptans such as octyl mercaptan, dodecyl mercaptan and tert-dodecyl mercaptan, and styrene dimers.

[Polymerization Initiator] The radical polymerization initiator used in the present invention can be appropriately used as long as it is water-soluble.
For example, persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4'-azobis-4-cyanovaleric acid and its salts, 2,2'-azobis (2-amidinopropane) salts, etc.), Peroxide compounds and the like.

Further, the above radical polymerization initiator can be used as a redox initiator in combination with a reducing agent as required. By using a redox-based initiator, the polymerization activity is increased, the polymerization temperature can be reduced, and a further reduction in the polymerization time can be expected.

As the polymerization temperature, any temperature may be selected as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator. For example, a temperature in the range of 50 ° C. to 90 ° C. is used. However, by using a polymerization initiator started at room temperature, for example, a combination of hydrogen peroxide and a reducing agent (such as ascorbic acid), polymerization can be performed at room temperature or higher.

[Surfactant] In order to carry out emulsion polymerization using the above-mentioned radical polymerizable monomer, it is necessary to carry out emulsion polymerization using a surfactant. The surfactant that can be used at this time is not particularly limited, but the following ionic surfactants can be mentioned as preferred examples.

Examples of the ionic surfactant include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkyl polyethersulfonate, 3,3-
Sodium disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6-sulfonate, ortho-carboxybenzene-azo-dimethylaniline,
2,2,5,5-tetramethyl-triphenylmethane-
4,4-diazo-bis-β-naphthol-6-sulfonate, etc.), sulfates (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, laurin) Sodium, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, etc.).

Further, nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, a combination of polypropylene oxide and polyethylene oxide, an ester of polyethylene glycol and higher fatty acid, an alkylphenol polyethylene oxide, an ester of higher fatty acid and polyethylene glycol, an ester of higher fatty acid and polypropylene oxide, a sorbitan ester Etc. can be given.

In the present invention, these are mainly used as emulsifiers at the time of emulsion polymerization, but they may be used for other steps or purposes.

[Colorant and Magnetic Particles] The magnetic particles used in the present invention can also be used as a colorant.
The shape is preferably spherical.

The reason for this is that the particles are fused in an aqueous medium, so that the surface is spherical, so that the formation of the electric double layer is stable and the fusion can be uniform. In addition, even when the magnetic particles are present in the resin particles, the spherical shape enables the surface of the magnetic particles to be uniformly wetted with the monomer, and the magnetic particles do not desorb, and are stable. Resin particles containing the prepared magnetic particles can be prepared.

Here, the magnetic particles having a spherical shape have a ratio of the major axis to the minor axis of about 1.0 to 0.80. In actual measurement, it is magnified 10,000 times by observation with an electron microscope, and 500 samples are randomly sampled to determine the average value of the measured values.

The magnetic material used in the present invention has a number average primary particle size of 0.05 to 0.5 μm, preferably 0.1 to 0.5 μm.
0.4 μm is preferred.

The magnetic particles preferably contained in the present invention include powders of ferromagnetic metals such as iron, cobalt and nickel which are magnetized in a magnetic field, or magnetite, γ-Fe ₂ O ₃ , ferrite, etc. Alloys and compounds can be used. These magnetic particles are BET by nitrogen adsorption method.
The specific surface area is preferably 1 to 20 m ² / g, especially 2.5
１２12 m ² / g, for example, those described in Japanese Patent Publication No. 1-40976 are preferred. The content of these magnetic particles in the developer is 20 to 80% by weight, preferably 30 to 50% by weight.

As the coloring agent, only the magnetic particles described above may be used, but if necessary, an inorganic pigment and an organic pigment may be used in combination.

Conventionally known inorganic pigments can be used. Specific inorganic pigments are exemplified below.

Examples of black pigments include furnace black, channel black, acetylene black,
Carbon black such as thermal black and lamp black is used.

The colorant can be used after surface modification. As the surface modifier, a conventionally known one can be used, and specifically, a silane coupling agent, a titanium coupling agent, an aluminum coupling agent and the like can be preferably used.

A so-called external additive can be added to the toner obtained in the present invention for the purpose of improving the fluidity and the cleaning property. These external additives are not particularly limited, and various inorganic fine particles,
Organic particulates and lubricants can be used.

Conventionally known inorganic fine particles can be used. Specifically, silica, titanium, alumina fine particles and the like can be preferably used. These inorganic fine particles are preferably hydrophobic. Specifically, as silica fine particles, for example, commercial products R-805, R-976, R-974, and R-97 manufactured by Nippon Aerosil Co., Ltd.
2, R-812, R-809, HVK- manufactured by Hoechst
2150, H-200, commercial product TS- manufactured by Cabot Corporation
720, TS-530, TS-610, H-5, MS-
5 and the like.

Examples of the titanium fine particles include commercially available products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., and commercially available products MT-100S, MT-100B and MT-5 manufactured by Teica.
00BS, MT-600, MT-600SS, JA-
1. Commercial products TA-300SI, TA-
500, TAF-130, TAF-510, TAF-5
10T, commercial products IT-S, IT-OA manufactured by Idemitsu Kosan Co., Ltd.
IT-OB, IT-OC and the like can be mentioned.

Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As this, a homopolymer such as styrene or methyl methacrylate or a copolymer thereof can be used.

Examples of the lubricant include salts of zinc, aluminum, copper, magnesium, calcium and the like of stearic acid, salts of zinc, manganese, iron, copper and magnesium of oleic acid, and zinc, copper, magnesium and calcium of palmitic acid. Metal salts of higher fatty acids such as salts of linoleic acid such as zinc and calcium, and salts of ricinoleic acid such as zinc and calcium.

The addition amount of these external additives is preferably about 0.1 to 5% by weight based on the toner.

<< Manufacturing Step >> The manufacturing step of the polymerized toner of the present invention is a polymerization step of preparing resin particles containing resin particles or magnetic particles by emulsion polymerization, and preparing a resin in an aqueous medium by using the resin particle dispersion. A step of fusing particles and resin particles containing magnetic particles or magnetic particles, a washing step of immersing the obtained particles in an aqueous medium to remove a surfactant, a step of drying the obtained particles, It comprises an external additive adding step of adding an external additive and the like to the particles obtained by drying. Here, the resin particles may be colored particles. Further, non-colored particles can be used as the resin particles.In this case, the colorant can be further colored by adding a colorant particle dispersion to the dispersion of the resin particles and then fusing the dispersion in an aqueous medium. it can.

In particular, as a fusion method, a method of performing salting out using resin particles produced in the polymerization step and performing fusion is preferable. When non-colored resin particles are used, the resin particles and the colorant particles can be salted out and fused in an aqueous medium.

Further, in addition to the colorant and the release agent, a charge control agent or the like, which is a component of the toner, can be added as particles in this step.

Here, the aqueous medium is composed of water as a main component and has a combined amount of water of 50% by weight or more. Examples of the solvent other than water include an organic solvent soluble in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Methanol, an organic solvent that does not dissolve the resin,
Alcohol organic solvents such as ethanol, isopropanol and butanol are particularly preferred.

The disperser for dispersing the magnetic material is not particularly limited, but is preferably an ultrasonic disperser, a mechanical homogenizer,
Examples thereof include a pressure disperser such as Menton Gorin and a pressure homogenizer, and a medium disperser such as a sand grinder, a Getzman mill and a diamond fine mill.

As the surfactant used here, the above-mentioned surfactants can be used.

In the salting-out / fusion step, a salting-out agent comprising an alkali metal salt or an alkaline earth metal salt is used as a coagulant having a critical coagulation concentration or more in water in which resin particles and magnetic particles are present. This is a step of adding salt and then heating the resin particles to a temperature equal to or higher than the glass transition point to promote salting out and simultaneously perform fusion. In this step, a method may be used in which an organic solvent that is infinitely soluble in water is added, and the glass transition temperature of the resin particles is substantially lowered to effectively perform fusion.

The alkali metal salt and alkaline earth metal salt used as salting-out agents include lithium, potassium, sodium and the like as alkali metals, and magnesium, calcium, strontium, barium and the like as alkaline earth metals. And preferably potassium, sodium, magnesium, calcium and barium. Examples of the constituents of the salt include chloride, bromide, carbonate, sulfate and the like.

When the fusion of the present invention is carried out by salting out / fusing, it is preferable to minimize the time of standing after adding the salting out agent. Although the reason for this is not clear, the aggregation state of the particles fluctuates depending on the standing time after salting out,
There are problems that the particle size distribution becomes unstable and the surface properties of the fused toner fluctuate. The temperature at which the salting-out agent is added must be at least equal to or lower than the glass transition temperature of the resin particles. The reason for this is that if the temperature at which the salting-out agent is added is higher than the glass transition temperature of the resin particles, the salting-out / fusion of the resin particles proceeds rapidly, but the particle size cannot be controlled, and There is a problem that particles having a particle size are generated. The range of the addition temperature may be lower than the glass transition temperature of the resin, but is generally 5 to 55 ° C, preferably 10 to 45 ° C.

Further, in the present invention, it is preferable to use a method in which a salting-out agent is added at a temperature lower than the glass transition temperature of the resin particles, and thereafter, the temperature is raised as quickly as possible and heated to a temperature higher than the glass transition temperature of the resin particles. The time until the temperature rise is preferably less than 1 hour. Further, it is necessary to raise the temperature promptly, but the rate of temperature increase is preferably 0.25 ° C./min or more. The upper limit is not particularly clear, but if the temperature is raised instantaneously, salting out proceeds rapidly, and there is a problem that particle size control is difficult to perform.

Here, the particle diameter of the toner obtained by fusing according to the present invention is preferably 3 to 9 μm in terms of volume average particle diameter. These toners have a volume average particle diameter of Coulter Counter TA-II, Coulter Multisizer, SLAD110
0 (Shimadzu Corporation laser diffraction particle size analyzer) or the like. Coulter counter T
For A-II and Coulter Multisizer, 2.0 to 40 μm using an aperture with an aperture diameter of 100 μm
Is measured using the particle size distribution in the range of.

The shape of the toner obtained by fusing has a shape factor represented by the following equation in the range of 1.3 to 2.2 and a shape factor in the range of 1.5 to 2.0. Is preferably 80% by number or more.

Shape factor = ((maximum diameter / 2) ² × π) / projected area This shape factor is obtained by taking a photograph in which the toner particles are magnified 500 times with a scanning electron microscope, and SCANNING IMAGE ANALYS
Analyze the photographic image using "ER" (manufactured by JEOL Ltd.). At this time, the shape factor of the present invention is measured by the above formula using 500 toner particles.

If the arithmetic mean value of the shape factor is less than 1.3, the shape becomes spherical, so that the so-called adhesion to the photoreceptor is increased, and cleaning failure is likely to occur. Further, since the toner particles are spherical, conveyance of the toner to the developing area becomes unstable, and a problem of causing image unevenness is likely to occur.

On the other hand, when the shape factor exceeds 2.1, the irregular shape becomes high, and when mechanical stress is applied, the toner is crushed and fine powder is likely to be generated. In the magnetic one-component development, contamination of the developer carrying member and the developer layer regulating member is easily caused, and image defects such as fog due to a decrease in toner chargeability are likely to occur.

Further, when the number of toner particles having a shape coefficient in the range of 1.5 to 2.0 is 80% by number or more, the distribution of the shape can be made uniform. Since the amount of the irregular toner can be reduced, the above-described problem can be suppressed for a long time.

[Tonerization Step] In the tonerization step, the toner particles obtained above may be used as they are, but for the purpose of, for example, improving the fluidity, chargeability, and cleaning properties, the above-mentioned external addition is performed. An agent may be added. As a method for adding the external additive, various known mixing devices such as a Turbula mixer, a Hensiel mixer, a Nauta mixer, and a V-type mixer can be used.

The toner may contain a material capable of imparting various functions as a toner material in addition to the colorant and the release agent. Specific examples include a charge control agent. These components are added at the stage of emulsion polymerization of the resin particles, the dispersion is added, the resin particles and the colorant particles are added at the same time in the salting-out / fusion step, and the toner particles are included in the toner. It can be added by various methods such as a method of adding it to an aqueous solution. Preferable methods include a method in which the charge control agent particles and / or the release agent particles are added in the form of a dispersion in the step of emulsion polymerization of the resin particles, and the method in which the resin particles and the colorant are added in the salting out / fusion step. A method in which charge control agent particles and / or release agent particles are added together with the particles in the form of a dispersion, and then salted out / fused is used.

It is preferable to use various known release agents which can be dispersed in water. Specifically, olefinic waxes such as polypropylene and polyethylene, modified products thereof, natural waxes such as carnauba wax and rice wax,
An amide wax such as a fatty acid bisamide can be used. It has already been mentioned that these are preferably added as release agent particles and are preferably salted out / fused together with the resin or colorant.

The charge control agents are also various known ones.
What can be dispersed in water can also be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines,
Quaternary ammonium salt compounds, azo-based metal complexes, salicylic acid metal salts or metal complexes thereof.

The particles of the release agent and the charge controlling agent preferably have a number average primary particle diameter of about 10 to 500 nm in a dispersed state.

<< Developer >> The developer (toner) used in the present invention is a magnetic one-component developer (magnetic one-component toner) as described above.

<< Image Forming Method >> In the image forming method used in the present invention, the electrostatic latent image holding member and the developer carrying member are arranged at a fixed gap (a) in the developing section, and the developer is This is an image forming method in which a developer layer is regulated to a thickness smaller than the gap (a) by the layer regulating member and conveyed to the developer carrier, and an alternating electric field is applied in the developing section for development.

Various photosensitive members can be used as the electrostatic latent image holding member. Specifically, selenium, arsenic selenium, selenium tellurium, a stacked organic photoreceptor comprising a charge generation layer and a charge transport layer such as an inorganic photoreceptor such as selenium, selenium telluride, and amorphous silicon, and a single-layer constitution comprising a mixture of a charge transport substance and a charge generation substance Organic photoreceptors and the like can be given.

A particularly preferred photosensitive member is an amorphous silicon photosensitive member or a laminated organic photosensitive member.

The present invention can also be used in an image forming apparatus by electrophotography, particularly in an apparatus for forming an electrostatic latent image on a photosensitive member by a modulated beam modulated with digital image data from a computer or the like.

In recent years, in the field of electrophotography and the like in which an electrostatic latent image is formed on a photoreceptor and this latent image is developed to obtain a visible image, it is easy to improve the image quality, convert, edit, etc., and obtain a high quality image. Research and development of an image forming method employing a digital method capable of forming are being actively conducted.

As a scanning optical system which modulates light by a digital image signal from a computer or a copy original used in the image forming method and apparatus, an acousto-optic modulator is interposed in a laser optical system, and the acousto-optic modulator is used for the light. There is a device for modulating the light and a device for directly modulating the laser intensity using a semiconductor laser. These scanning optical systems form a dot-like image by spot exposure on a uniformly charged photoconductor.

The beam emitted from the above-mentioned scanning optical system has a round or elliptical luminance distribution approximating a normal distribution with a skirt spreading left and right. One or both of the scanning direction and the sub-scanning direction has an extremely narrow round or elliptical shape of 20 to 100 μm.

Examples of the surface material of the organic photoreceptor used in the present invention include silicone resin, vinylidene chloride, ethylene-vinyl chloride, styrene-acrylonitrile, styrene-methyl methacrylate, styrene, polyethylene terephthalate, and polycarbonate. There is no limitation, and a polymer, a copolymer, a blend, or the like from another monomer can be used. A particularly preferred material is polycarbonate, and a more preferred resin is bisphenol Z-type polycarbonate.

The material of the support of the organic photoreceptor is not particularly limited. Aluminum and its alloys widely used at present can be used.

An intermediate layer (also referred to as an undercoat layer) is usually provided thereon. Typical examples include a ceramic type made of a silane coupling agent and an organic chelate compound, and a resin type made of a polyamide resin.

A photosensitive layer is provided on the undercoat layer. The photosensitive layer has a so-called function separation type laminated structure having a charge generation layer and a charge transport layer.

The charge generation layer (CGL) is often formed by dispersing a charge generation material (CGM) in a binder resin as required. The CGM is not particularly limited, but may be an azo pigment, a polycyclic quinone pigment such as anthraquinone,
A quinone imine pigment, an azomethine pigment, a cyanine pigment, a benzoquinone pigment, a perylene pigment, a metal or metal-free phthalocyanine pigment, or the like can be used. These may be used as a mixture of two or more as necessary.

Examples of the binder resin usable for the charge generation layer include polystyrene resin, polyethylene resin,
Polypropylene resin, acrylic resin, methacrylic resin,
Vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and a copolymer containing two or more of these resin repeating units. Polymer resins, such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin,
In addition, a high molecular organic semiconductor such as poly-N-vinyl carbazole may be used, but is not limited thereto.

The charge transport layer (CTL) is composed of a charge transport material (CTM) alone or together with a binder resin. As the CTM, for example, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives, oxazolone Derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives,
Phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, but are not limited thereto. Not necessarily. These may be used alone or in combination of two or more.

Examples of the binder resin usable for the charge transport layer include polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate resin, and styrene-methacrylic acid. Ester copolymer resins and the like can be mentioned. Although not limited thereto, a particularly preferred resin is a polycarbonate resin, and a more preferred resin is a bisphenol Z-type polycarbonate resin.

The electrophotographic photoreceptor applied to the present invention preferably contains a compound having a fluorine atom and / or a compound having a silicone atom in the charge transport layer and / or the protective layer serving as the photoreceptor surface layer. The abundance of the compound having a fluorine atom and / or a silicon atom present on the surface of the photoreceptor is represented by the ratio of fluorine atom and / or silicon atom to carbon atom as measured by XPS: F / C = 0.03 to 1.00 Those in the range of Si / C = 0.03 to 1.00 are preferable. More preferably, F / C = 0.06 to 0.80 and Si / C = 0.06 to 0.80.

The compounds having a fluorine atom and / or a silicone atom used for the surface layer are exemplified below.

As specific examples of the compound having a fluorine atom used for the surface layer, known fluorine resins may be mentioned.
One or more of ethylene tetrafluoride, ethylene trifluoride, ethylene tetrafluoride, propylene hexafluoride, vinyl fluoride, vinylidene fluoride, ethylene dichloride diethylene and their copolymers Is appropriately selected. Also, carbon fluoride and the like can be used.

Polymerization / copolymerization with a polymerizable monomer having a fluorine atom (fluorine-based polymerizable monomer) or a polymerizable monomer containing no fluorine atom (non-fluorine-based polymerizable monomer) A block or graft polymer, a surfactant, a macromonomer, or the like containing a fluorine-containing segment synthesized from the above can be used alone or in combination with the above-mentioned fluorine-based resin.

In particular, the combined use with a fluorine-based graft polymer having a continuous fluorine-based segment is preferable in terms of facilitating dispersion of the fluorine-based resin and easy control of the F / C ratio on the surface.

Next, specific examples of the compound having a silicon atom used in the present invention include monomethylsiloxane three-dimensional crosslinked product, dimethylsiloxane-monomethylsiloxane three-dimensional crosslinked product, ultrahigh molecular weight polydimethylsiloxane,
A block polymer containing a polydimethylsiloxane segment, a graft polymer, a surfactant, a macromonomer, a terminal-modified polydimethylsiloxane and the like are used.

Further, a compound having a polycarbonate structure containing a silicone atom may be used.

The fluorine-based or silicone-based polymer is compatible with the resin layer of the charge transporting layer and / or the protective layer to be added, or has a similar structure if not completely compatible. It is preferable to select those having affinity.

In the case where the above-mentioned fluorine-based or silicone-based polymer is contained in the charge transport layer or the protective layer forming the surface layer of the present invention, it is compatible with these polymers or the charge transport substance and other additives present at the same time. A polymer having good solubility is also used as a binder. Among these non-fluorine-based or non-silicone-based polymers, the most preferably used polymer is a polycarbonate soluble in an aromatic hydrocarbon solvent or a halogenated aromatic hydrocarbon.

The weight average molecular weight of the polycarbonate is preferably 10,000 or more, particularly preferably 20,000 or more.

The developer carrying member is constituted by a sleeve in which a magnet fixed inside is arranged, and the developer (toner) is transported to the developing area by rotating the sleeve. The material is preferably stainless steel or aluminum. A particularly preferred example is one in which a phenol resin in which conductive carbon is dispersed is coated on the surface of an aluminum sleeve. The sleeve preferably has a diameter of 10 to 50 mm.

The developer layer regulating member is used to uniformly regulate the toner layer on the developer carrier. The developer layer regulating member may be made of a magnetic plate or a non-magnetic plate. A method to regulate the toner layer by forming a certain gap between
Alternatively, a method in which a member having rubber elasticity such as urethane is brought into contact with the developer carrying member, and a method in which an elastic metal plate such as a phosphor bronze plate is brought into contact with the developer carrying member can be given.

The developer layer is conveyed to the developer carrier in a layer thinner than the gap (a) between the developer carrier and the electrostatic latent image carrier. The preferred range of the gap (a) is 100 to 500 μm, and the developer layer is conveyed to be thinner than this gap.
It is preferable to be transported in a layer of 0 to 300 μm.

Further, it is preferable to apply an alternating electric field between the developer carrier and the electrostatic latent image carrier. By applying this alternating electric field, the toner can fly effectively. As the condition of the alternating electric field, it is preferable that the AC frequency f is 200 to 4,000 Hz and the AC voltage Vpp is 500 to 3,000 V. When this alternating electric field is used, it is necessary that the toner has uniform chargeability and magnetism. That is, when the toner has a distribution of magnetism and chargeability among toners, the effect of pulling back weakly chargeable toner and the like due to the alternating electric field is offset, and as a result, the effect of improving image quality is reduced. The image quality can be further improved by the shape uniformity and magnetic uniformity of the toner formed by fusing in an aqueous medium as in the present invention.

Hereinafter, the developing device of the image forming method of the present invention will be specifically described.

The developer carrying member may be hereinafter referred to as a sleeve, and the developer layer thickness regulating member may be referred to as various blades.

In the apparatus shown in FIG. 1, a developing device having a developer layer regulating member (magnetic blade) 11 and a developing sleeve 4 containing a multipolar permanent magnet 14 is used.
The latent image is developed using a magnetic one-component developer (toner particles) 10.

The magnetic blade as the developer layer regulating member is a preferable developer layer regulating member because the regulation accuracy of the layer thickness is high for the mounting accuracy. However, any method can be used without any particular limitation as long as the method can accurately regulate the thickness of the thin layer.

In the developing section, an alternating electric field and / or a DC bias is applied between the conductive base (support) 16 of the electrostatic latent image holder (photosensitive drum) 1 and the developing sleeve 4 by the bias applying means 12. Has been applied.

Although not shown, when the transfer paper is conveyed and reaches the transfer section, the transfer charger charges the transfer paper from the back surface (the surface opposite to the photosensitive drum side), and the surface of the photosensitive drum is charged. The upper toner image is electrostatically transferred onto a transfer paper (recording material). The transfer paper separated from the photosensitive drum is guided to a heat and pressure roller fixing device, and the developer image on the transfer paper is fixed by the fixing device. The developer remaining on the photosensitive drum 1 after the transfer process is removed by a cleaning device having a cleaning blade. After the cleaning, the photosensitive drum is neutralized by the pre-charging exposure, and the process starting from the charging process by the primary charger is repeated again.

Returning to the description of FIG. 1, the photosensitive drum (electrostatic latent image carrier) 1 has a photosensitive layer 15 as a surface layer and a conductive substrate 16 and moves in the direction of the arrow. A non-magnetic cylindrical developing sleeve 4 as a developer carrier rotates so as to advance in the same direction as the surface of the electrostatic latent image holding member in the developing section. Developing sleeve 4
A multi-pole permanent magnet (magnet roll) 14 serving as a magnetic field generating means is arranged so as not to rotate. The magnetic one-component developer used in the image forming method of the present invention in the developing unit 9 is thinly applied on the surface of the developing sleeve 4 by the magnetic blade 11, and the friction causes the toner particles 10 to be charged.

An alternating electric field is applied between the developer carrier 4 and the electrostatic latent image holder 1 in the developing section. The condition of the AC bias is that the AC frequency f is 200 to 4,000 Hz and the AC voltage is Vpp is preferably in the range of 500 to 3,000V.

When the developer (toner) is transferred in the developing portion, the developer particles are transferred to the electrostatic image side by the action of the electrostatic force and the AC bias on the surface of the electrostatic latent image holding member.
Further, it is preferable that a stirring means 13 in the developer container is provided in the developer container.
Is positively sent to the vicinity of the developing sleeve 4, so that a uniform developer layer can be formed up to just before the developer runs out.

[0135]

Next, embodiments of the present invention will be specifically described, but the present invention is not limited to these embodiments. In the description, “parts” means “parts by weight”.

Example 1 In a resin container having an inner volume of 20 L (liter), 0.90 kg of Adeka Hope LS-90 (sodium n-dodecyl sulfate manufactured by Asahi Denka Co., Ltd.) and 10.0 L of pure water were added and stirred and dissolved. To this liquid, 3.0 kg of magnetite particles having a shape coefficient of 0.85, a number average primary particle size of 0.2 μm, and a BET value of 7.2 m ² / g were gradually added with stirring, and stirred well for 1 hour after the addition. I do. Next, continuous dispersion was performed for 2 hours using a sand grinder (medium type disperser). This dispersion is referred to as “magnetic particle dispersion 1”.

In a 10 L stainless steel pot, 0.055% sodium dodecylbenzenesulfonate (Kanto Chemical Co., Ltd.) was added.
Then, add 4.0 L of ion-exchanged water and stir and dissolve at room temperature. This is designated as an anionic surfactant solution A.

In a 10 L stainless steel pot, 0.014 kg of Newcol 565C (manufactured by Nippon Emulsion Co., Ltd.) is added, and 4.0 L of ion-exchanged water is added, followed by stirring and dissolving at room temperature. This is designated as nonionic surfactant solution B.

223.8 g of potassium persulfate (manufactured by Kanto Chemical Co., Ltd.) was placed in a 20 L enamel pot, and ion-exchanged water 1 was added.
Add 2.0 L and stir and dissolve at room temperature. This is called initiator solution C.

A 100 L GL (glass lining) reactor equipped with a temperature sensor, a cooling pipe, and a nitrogen introducing device was charged with W.
3.41 kg of the AX emulsion (polypropylene emulsion having a number average molecular weight of 3000: number average primary particle diameter of 120 nm / solid content = 29.9%), an anionic surfactant solution A and a nonionic surfactant solution B are added and stirred. Start. Next, 44.0 L of ion-exchanged water is added.

Heating is started, and when the liquid temperature reaches 75 ° C., an initiator solution C is added. Thereafter, the liquid temperature is reduced to 7
While controlling at 5 ± 1 ° C., 12.1 kg of styrene, 2.88 kg of n-butyl acrylate and 1.04 g of methacrylic acid
kg and 548 g of t-dodecyl mercaptan.

Further, by raising the liquid temperature to 80 ± 1 ° C.,
Heating and stirring were performed for hours.

The temperature of the solution is cooled to 40 ° C. or less, and the stirring is stopped. The mixture was filtered through a pole filter and the latex was filtered.
A.

Incidentally, the glass transition temperature of the resin particles in the latex-A is 57 ° C., the softening point is 121 ° C., the molecular weight distribution is a weight average molecular weight of 127,000, and a weight average particle diameter is 120.
nm.

In a new 10 L stainless steel pot, add sodium dodecylbenzenesulfonate (Kanto Chemical Co., Ltd.)
After adding 055 kg, 4.0 L of ion-exchange pure water is added, and the mixture is stirred and dissolved at room temperature. This is used as an anionic surfactant solution D
And

In a 10 L stainless steel pot, 0.014 kg of Newcol 565C (manufactured by Nippon Emulsifier) is added, and 4.0 L of ion-exchange pure water is added, followed by stirring and dissolving at room temperature. This is designated as a nonionic surfactant solution E.

200.7 g of potassium persulfate (manufactured by Kanto Kagaku) was placed in a 20 L enamel pot, and ion-exchanged water 1 was added.
Add 2.0 L and stir and dissolve at room temperature. This is designated as an initiator solution F.

A WAX emulsion (polypropylene emulsion having a number average molecular weight of 3000: a number average primary particle diameter of 120 nm) was placed in a 100 L GL reactor (a stirring blade was a Faudler blade) equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a comb baffle. 8.41 kg (solids concentration 29.9%)
And the anionic surfactant solution D and the nonionic surfactant solution E are added and stirring is started. Next, ion-exchanged water 4
Charge 4.0L.

Heating is started, and when the liquid temperature reaches 70 ° C., an initiator solution F is added. At this time, styrene 1
1.0 kg, 4.00 kg of n-butyl acrylate, 1.04 kg of methacrylic acid, and t-dodecyl mercaptan 9.
And a solution obtained by previously mixing 02 g with the mixture.

Thereafter, the liquid temperature was controlled at 72 ± 2 ° C.
Heating and stirring were performed for 6 hours. Further, the liquid temperature is set to 80 ± 2 ° C.
And heated and stirred for 12 hours.

The temperature of the solution is cooled to 40 ° C. or less, and the stirring is stopped. The mixture was filtered through a Pall filter, and this dispersion was used as Latex-B.

The glass transition temperature of the resin particles in Latex-B is 58 ° C., the softening point is 132 ° C., the molecular weight distribution is weight average molecular weight 245,000, and the weight average particle size is 110.
nm.

In a 35 L stainless steel pot, 5.36 kg of sodium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) as a salting-out agent and 20.0 L of ion-exchanged water are added and stirred and dissolved. This is designated as sodium chloride solution G.

1.00 g of FC-170C (manufactured by Sumitomo 3M, nonionic surfactant) is placed in a 2 L glass beaker, 1.00 L of ion-exchanged water is added, and the mixture is stirred and dissolved. This is designated as nonionic surfactant solution H.

The latex-A = 2 prepared above was placed in a 100 L SUS reactor (with stirring blades as anchor blades) equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a comb-shaped bath.
0.0 kg, 5.2 kg of latex-B, the whole amount of the magnetic particle dispersion 1 and 20.0 kg of ion-exchanged water are added and stirred. Then, the mixture was heated to 40 ° C., and 6.00 kg of sodium chloride solution G, isopropanol (manufactured by Kanto Kagaku),
The nonionic surfactant solution H is added in this order. Thereafter, after standing for 10 minutes, the temperature was raised and the liquid temperature was 85
The temperature is raised to 60 ° C. in 60 minutes. At a liquid temperature of 85 ° C ± 2 ° C, 6
Heat and stir for hours to effect salting out / fusion. Thereafter, the mixture is cooled to 40 ° C. or less and the stirring is stopped. The solution is filtered through a sieve having an opening of 45 μm, and this filtrate is used as an association liquid.

Next, non-spherical particles in the form of a wet cake were collected from the association liquid using a Nutsche. afterwards,
It was washed with ion-exchanged water.

The wet cake-like non-spherical particles having been washed as described above are taken out from the nutsche.
Spread them into pieces into pieces. After covering with kraft paper, it was dried with a blow dryer at 40 ° C. for 100 hours.

[0158] The block-shaped non-spherical particles that had been dried were crushed by a Henschel pulverizer.

The non-spherical particles obtained as described above are referred to as “non-spherical particles 1”. "Non-spherical particles 1"
The molecular weight of the resin particles which are the components of the formula is weight average molecular weight =
550,000, softening point = 125 ° C., glass transition temperature = 57
° C, the volume average particle size = 6.53 µm, the shape factor is 1.92, and the shape factor in the range of 1.5 to 2.0 is 9
7% by number.

Example 2 In Example 1, 17.0 kg of magnetite particles having a shape factor of 0.85, a number average primary particle size of 0.2 μm, a BET value of 7.2 m ² / g, and styrene 12. 1 kg, 2.88 kg of n-butyl acrylate and 1.04 of methacrylic acid
kg and 548 g of t-dodecyl mercaptan are stirred well, and a dispersion obtained by dispersing with a sand grinder is used in place of the polymerizable monomer for preparing the latex-A. Non-spherical particle 2 "
I got

Example 3 Example 1 was repeated except that the magnetic powder used was magnetite particles having a shape factor of 0.54, a number average primary particle size of 0.3 μm, and a BET value of 3.2 m ² / g. Similarly, “non-spherical particles 3” were obtained.

Example 4 In Example 2, the magnetic powder was prepared by using a shape factor of 0.89, a number average primary particle size of 0.22 μm, and a BET value of 8.1 m ² / g.
"Non-spherical particles 4" were obtained in the same manner except that the magnetite particles were used.

Example 5 "Non-spherical particles 5" were obtained in the same manner as in Example 1, except that the temperature at the time of association was set to 95 ° C. and the association time was set to 7 hours.

Example 6 "Non-spherical particles 6" were obtained in the same manner as in Example 1 except that the association time during the association was changed to 4 hours.

Example 7 The following components were added to a 100 L GL reactor equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a comb baffle (the stirring blade was a Faudler blade).

Styrene 60 parts Butyl acrylate 40 parts Acrylic acid 8 parts Water 100 parts Nonionic emulsifier (Emulgen 950) 1 part Anion emulsifier (Neogen R) 1.5 parts Potassium persulfate 0.5 part The above aqueous solution mixture was stirred. Polymerization was performed at 70 ° C. for 8 hours to obtain an acidic polar group-containing resin emulsion (latex) having a solid content of 50%.

Toner preparation Latex 120 parts Magnetic particles used in Example 1 40 parts Chromium dye (Bontron-E81) 1 part Water 200 parts The above mixture was dispersed and stirred with a slasher at about 25 parts.
C. for 2 hours. Then, with further stirring, 65
C. and kept for 3 hours. The liquid dispersion obtained by cooling was subjected to Buchner filtration, washed with water, and vacuum dried at 50 ° C. for 10 hours to obtain “non-spherical particles 7”.

Comparative Example 1 165 g of styrene, 35 g of n-butyl acrylate, 10 g of phthalocyanine blue, 2 g of metal di-t-butylsalicylate, styrene-methacrylic acid copolymer =
8 g, 20 g of paraffin wax (mp = 70 ° C.) and 150 g of the magnetic powder used in Example 1 were heated to 60 ° C.
12000 using TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.)
Dissolved and dispersed uniformly at rpm. In addition, 2,2'-azobis (2,4-valeronitrile) 10 is used as a polymerization initiator.
g was added and dissolved to prepare a polymerizable monomer composition.
Then, 450 g of a 0.1 M sodium phosphate aqueous solution was added to 710 g of ion-exchanged water, and the mixture was added to a TK homomixer at 120 g.
1.0M calcium chloride 68 while stirring at 00 rpm.
g was gradually added to prepare a suspension in which tricalcium phosphate was dispersed.

The polymerizable monomer composition was added to the suspension, and the mixture was stirred with a TK homomixer at 10,000 rpm for 20 minutes to granulate the polymerizable monomer composition. Then 8
The reaction was performed at 0 ° C. for 10 hours. Tricalcium phosphate was dissolved and removed with hydrochloric acid, followed by filtration, washing and drying to obtain spherical particles having a volume average particle size of 7.9 μm. This is designated as “Comparative Particle 1”.

Comparative Example 2 100 parts of styrene-acrylic resin, 40 parts of magnetic particles, and 4 parts of low molecular weight polypropylene (number average molecular weight = 3000) were melted, kneaded, and pulverized to give colored particles having a volume average particle size of 6.9 μm. I got This is designated as “Comparative Particle 2”.

The following table shows the shape factors of the “non-spherical particles 1” to “non-spherical particles 7”, “comparative particles 1” and “comparative particles 2” described above.

[0172]

[Table 1]

Next, hydrophobic silica (number-average primary particle diameter = 12 nm) was added to each of the “non-spherical particles 1” to “non-spherical particles 7”, “comparison particles 1”, and “comparison particles 2”.
Was added to obtain a toner. These are referred to as “Toner 1 of the present invention” to “Toner 7 of the present invention”, “Comparative Toner 1”, and “Comparative Toner 2”.

Evaluation Evaluation was made using an apparatus having a mechanism as shown in FIG.

Photoreceptor used The laminated organic photoreceptor shown below was used as the photoreceptor.

Production of Photoconductor A A photoconductor drum having a layer structure of an intermediate layer, a charge generation layer, a charge transport layer, and a second charge transport layer on a drum-type aluminum substrate (support) having a diameter of 60 mm was prepared. .

The structure of the photoreceptor is shown below.

1: Undercoat layer coating solution Titanium chelate compound “TC-750” (manufactured by Matsumoto Pharmaceutical Co., Ltd.) 30 parts Silane coupling agent “KBM-503” (manufactured by Shin-Etsu Chemical Co., Ltd.) 17 parts 2-propanol 150 parts The following CGL coating solution was dispersed and prepared on the pulling layer, and applied to a thickness of 0.5 μm to obtain CGL.

2: CGL coating liquid 10 parts of Y-type titanyl phthalocyanine (A1 of the following “Chemical Formula 1”) 10 parts of silicone resin “KR-5240” (manufactured by Shin-Etsu Chemical Co., Ltd.) 1000 parts of t-butyl acetate 1000 parts Dispersed for 20 hours using a sand mill.

The following CTL coating solution was applied on the above-mentioned CGL so as to have a dry film thickness of 23 μm, and dried at 100 ° C. for 1 hour to form a CTL stack.

3: CTL coating solution CTM (CTM1 of the following “Chemical Formula 1”) 224 parts Binder resin (Mv = 30,000) 560 parts Irganox 1010 (manufactured by Sankyo) 21 parts 1,2-dichloroethane 2800 parts 4A: second part CTL coating liquid CTM (CTM1) 224 parts Carbon fluoride fine powder (average particle size: 0.23 μm, manufactured by Central Glass Co., Ltd.) 7 parts Binder resin (B1 of the following Chemical Formula 1) (Mv = 30,000) 20 Part Monochlorobenzene 120 parts Dichloromethane 80 parts The above composition was dispersed, mixed and dissolved in a sand mill. This was coated on the CTL by a circular slide hopper coating machine to form a photosensitive layer A having a surface layer of 5 μm.

[0182]

Embedded image

Production of Photoconductor B The same components as in Production Example A were prepared up to the aluminum substrate, conductive layer, undercoat layer, and CTL layer.

Next, as the second CTL, the following coating was dispersed and mixed and dissolved by a sand mill, and this was coated on the CTL by a circular slide coating, and a surface layer of 5 μm was provided to obtain a photosensitive drum B. .

4B: Second CTL coating solution CTM (CTM1) 15 parts True spherical three-dimensionally crosslinked polysiloxane fine particles (average particle size 0.29 μm, manufactured by Toshiba Silicone Co., Ltd.) 5 parts Binder resin (Mv = 80,000) 10 Part Resin (resin B1 having the above structure) (Mv = 30,000) 10 parts Monochlorobenzene 120 parts Dichloromethane 80 parts The surface of the photosensitive drum B is composed of 8.4% Si atoms and 77.3% C atoms. The Si / C ratio was 0.11.

Production of Photoconductor Drums C to F In the production of photoconductor drum A, the following photoconductors were obtained by changing the amount of carbon fluoride added.

Photoconductor C: F / C ratio = 0.02 Photoconductor D: F / C ratio = 0.56 Photoconductor E: F / C ratio = 0.71 Photoconductor F: F / C ratio = 0. 93 Production of Photoreceptor Drums G to J In the production example of the photoreceptor drum B, the following photoreceptors were obtained by changing the addition amount of the spherical three-dimensionally crosslinked polysiloxane fine particles.

Photoconductor G: Si / C ratio = 0.02 Photoconductor H: Si / C ratio = 0.53 Photoconductor I: Si / C ratio = 0.73 Photoconductor J: Si / C ratio = 0. 98 Further, an amorphous silicon photosensitive member was used as the drum K.

Photoconductor charging condition Charger; Scorotron charging voltage; Photoconductor charging potential (initial charging potential) 720 V Development condition DC bias: -500 V AC bias: Vpp = 1800 V, frequency = 20 k
Hz Dsd (distance between photoreceptor and developing sleeve); 600 μm Developer layer regulation; magnetic H-Cut method Developer layer thickness: 300 μm Developing sleeve diameter: 40 mm (with phenol resin coating with conductive carbon black dispersed on the surface) As a fixing method, a hot roll fixing was used, and untransferred toner remaining on the photoreceptor was removed using a blade cleaning method.

The transfer paper used was a paper having a continuous weight of 55 kg, and an image was formed in the vertical direction. As image forming conditions, a line drawing having a low printing ratio of 2% in a high-temperature and high-humidity environment (33 ° C., 85% RH) was used, and 50,000 sheets were printed intermittently on two sheets. Initial and final 500
At the time of 00 sheets, solid black, solid white, and halftone images were printed, and the image quality was evaluated using these images. The image density, fog density and halftone uniformity of the finished image were evaluated.

For image density, RD-918 manufactured by Macbeth was used, and the absolute reflection density was measured. The fog density was measured by a relative reflection density where the reflection density of the paper was "0". The uniformity of the halftone was visually determined, and the uniformity of the halftone image was evaluated. The rank was evaluated as follows.

Rank A: uniform image without unevenness Rank B: presence of thin stripe-like unevenness Rank C: presence of several thin stripe-like unevenness Rank D: presence of several or more clear stripe-like unevenness Items were evaluated with combinations of toner and photoreceptor shown in Table 2 below.

[0193]

[Table 2]

Evaluation results

[0195]

[Table 3]

As is clear from Table 3, Examples 1 to 17 in the present invention show good characteristics, while Comparative Examples 1 and 2
It can be seen that there is a problem in durability in any of the characteristics.

[0197]

According to the present invention, there is provided an image forming method which does not generate image defects such as fogging, image density reduction and image quality deterioration even in a long-term use in a non-contact development system using a magnetic one-component developer. A developer used for the method can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an apparatus for explaining an image forming method of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrostatic latent image holder (photosensitive drum) 4 developer carrier (developing sleeve) 10 toner particles 11 developer layer regulating member (magnetic blade) 14 multipolar permanent magnet 15 photosensitive layer 16 conductive substrate (support)

Continuing from the front page (72) Inventor Hiroyuki Yamada 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation F-term (reference) 2H005 AA02 AB03 FA06 2H077 AD06 AD13 AD23 AD24 AD36 AE04 EA13 EA16 FA13 FA25

Claims (4)

[Claims] An electrostatic latent image holding member and a developer carrying member are arranged in a developing section with a constant gap (a) provided therebetween, and the gap (a) is provided in the developer carrying member by a developer layer regulating member. In an image forming method in which the developer layer is conveyed while regulating the developer layer to a thickness smaller than that in the developing section, an alternating electric field is applied in the developing section, and the developer contains at least magnetic particles and resin particles in an aqueous medium. An image forming method, wherein the developer is a developer containing a toner fused by using the method. 2. An electrostatic latent image holding member and a developer carrying member are arranged at a predetermined gap (a) in a developing section, and the gap (a) is provided on the developer carrying member by a developer layer regulating member. In the image forming method in which the developer layer is regulated and transported to a thickness smaller than that of the above, and an alternating electric field is applied in the developing section to develop the resin layer, the developer contains resin particles containing at least magnetic particles in an aqueous medium. An image forming method, wherein the developer is a developer containing a toner fused by using the method. 3. An electrostatic latent image holding member and a developer carrying member are arranged at a predetermined gap (a) in a developing section, and the gap (a) is provided in the developer carrying member by a developer layer regulating member. The developer used in the image forming method in which the developer layer is conveyed while regulating the developer layer to a thickness smaller than that in the developing section, wherein the developer is at least spherical magnetic particles and resin particles And a toner obtained by fusing in a water-based medium. 4. An electrostatic latent image holding member and a developer carrying member are arranged at a predetermined gap (a) in a developing section, and the gap (a) is provided in the developer carrying member by a developer layer regulating member. The developer used in the image forming method in which the developer layer is conveyed while regulating the developer layer to a thickness smaller than that in the developing section, wherein the developer contains at least spherical magnetic particles. A developer comprising a toner obtained by fusing particles in an aqueous medium.