JP3087007B2 - Magnetic toner and image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic toner and an image forming method used in electrophotography, electrostatic recording, magnetic recording, and the like, and is applied to printers, copiers, facsimiles, and the like.

[0002]

2. Description of the Related Art Conventionally, many methods are known as electrophotography. In general, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means. The latent image is developed with a toner to form a visible image, and if necessary, the toner image is transferred to a transfer material such as paper, and then the toner image is fixed on the transfer material by heat, pressure, etc. to obtain a copy. Things.

As a method for visualizing an electric latent image, a cascade developing method, a magnetic brush developing method, a pressure developing method and the like are known. Further, a method is also used in which a magnetic toner is used and a rotating sleeve having a magnetic pole disposed at the center is used to fly between the photosensitive member and the sleeve by an electric field.

The one-component developing system does not require carrier particles such as glass beads and iron powder as in the two-component developing system, so that the developing device itself can be reduced in size and weight. Further, in the two-component developing method, since it is necessary to keep the toner concentration in the carrier constant, a device for detecting the toner concentration and supplying a necessary amount of toner is required. Therefore, the developing device also becomes large and heavy here. In the one-component developing system, such an apparatus is not required, so that the apparatus can be made small and light, which is preferable.

[0005] In recent years, LED and LBP printers have become the mainstream in the printer market, and the direction of technology has been increased to higher resolution, that is, from 240, 300 dpi to 400, 600, 800 dpi. ing. Accordingly, higher definition has been required for the developing system. In addition, the functions of the copying machine have been advanced, and the digital copying machine is moving toward digitalization. In this direction, a method of forming an electrostatic charge image with a laser is mainly used, so that the direction is also moving toward a higher resolution, and a high-resolution and high-definition developing method is required similarly to a printer. . For this reason, the particle size of toner has been reduced, and Japanese Patent Application Laid-Open Nos.
JP-A-91156, JP-A-2-214156, JP-A-2-284158, JP-A-3-181952
And Japanese Patent Application Laid-Open No. 4-162048 propose a toner having a specific particle size distribution and a small particle size.

Further, in a copying machine, a direction of higher speed and stabilization is always desired. In particular, a two-component developing system is mainly used for medium-speed machines and high-speed machines. This is because, with such a large machine, stability for high-speed long-term use becomes more important than the size and weight of the developing device. Generally, a two-component toner is colored with carbon black or the like, and the other components are mostly made of a polymer. Therefore, the toner particles are light and have no force to adhere to the carrier particles other than the electrostatic force. In particular, the toner particles are scattered at a high-speed development, and the lens, the original glass, the transport section, and the like are stained over a long period of use. Stability may be impaired. Therefore, a two-component toner has been put to practical use in which a magnetic substance is contained in the toner to make the toner heavier and, at the same time, adhere to magnetic carrier particles by magnetic force in addition to electrostatic force to prevent scattering.

[0007] As described above, toners containing magnetic substances are becoming more and more important.

In the one-component magnetic developing method, the toner is developed in a chain form (generally called "spikes") at the time of development, so that the resolution in the horizontal direction of the image is worse than that in the vertical direction. For example, a trailing phenomenon due to the protrusion of ears tends to occur in a non-image portion in the latter half of the developed image, and a rough image tends to occur more easily than in the two-component developing system. Therefore, as a method for further improving image reproducibility, it is conceivable to make the toner ears shorter and denser, and as a means of reducing the amount of the magnetic material in the toner, the toner layer thickness regulating member is strongly attached to the toner carrier. Means such as contact are considered. However, for example, when the amount of the magnetic material is reduced, the charge amount of the toner generally becomes excessively large, causing a so-called charge-up phenomenon, resulting in a decrease in image quality such as a decrease in image density and an increase in fog. The relationship between the magnetization strength of the magnetic toner and the shape of the ears is also qualitatively understood as follows. That is, when the magnetization strength of the magnetic toner is large, a strong attractive force along the magnetic field direction and a strong repulsive force in a direction perpendicular to the magnetic field are generated between the magnetic toners. Therefore, when the intensity of magnetization is large, the spikes formed by the magnetic toner are long, the density of the spikes on the toner carrier is coarse, and the individual spikes are thin. Conversely, if the magnetization strength of the magnetic toner is small, the ears are short and the density of the ears on the toner carrier is high, but the individual ears are thick because the bonds between the magnetic toner particles are not released. Shorter,
It is in an agglomerated state. In this case, the magnetic toner particles existing inside the ears have less chance of contacting the surface of the toner carrier, resulting in poor charging. Such poorly charged toner particles cause fogging on the image and lower the image quality.

In recent years, from the viewpoint of environmental protection, the primary charging and transfer process using a corona discharge, which has been conventionally used, to the primary charging and transfer process using a photosensitive member contact member are becoming mainstream.

For example, JP-A-63-149669 and JP-A-2-123385 have been proposed. These are related to the contact charging method and the contact transfer method, but contact the conductive elastic roller with the electrostatic latent image carrier,
The electrostatic latent image carrier is uniformly charged while applying a voltage to the conductive roller, and then a toner image is obtained by an exposure and development process, and then another voltage is applied to the electrostatic latent image carrier. The transfer material is passed through the conductive roller while pressing the conductive roller, and the toner image on the electrostatic latent image carrier is transferred to the transfer material. Then, a copy image is obtained through a fixing process.

However, in such a roller transfer method that does not use corona discharge, the transfer member is brought into contact with the photosensitive member via the transfer member at the time of transfer, so that the toner image formed on the photosensitive member is transferred to the transfer material. When the toner image is transferred, the toner image is pressed against the toner image, which causes a problem of partial transfer failure called so-called "missing transfer".

Further, as the diameter of the toner decreases, the adhesion force of the toner particles to the photoreceptor (mirror image force, van der Waals force, etc.) is smaller than the Coulomb force applied to the toner particles during transfer.
, And as a result, the transfer residual toner tends to increase.

Further, in the roller charging system, the physical and chemical action on the surface of the electrostatic latent image carrier due to discharge generated between the charging roller and the electrostatic latent image carrier is larger than in the corona charging system. In particular, in the combination with the organic photoconductor / blade cleaning, there is a defect that problems such as toner fusion on the photoconductor and poor cleaning due to deterioration of the photoconductor surface are likely to occur (direct charging / organic cleaning). The combination of photoreceptor / one-component magnetic developing method / contact transfer / blade cleaning is easy to reduce the cost and size and weight of the image forming apparatus. This is the mainstream method for printers and facsimile machines.)

Therefore, it is required that the toner and the image carrier used in such an image forming method have excellent releasability.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic toner and an image forming method which solve the above-mentioned problems of the prior art.

That is, an object of the present invention is to faithfully follow a manuscript,
It is an object of the present invention to provide a high-resolution and high-definition reproducible magnetic toner faithful to a signal, that is, substantially free of fogging and toner tailing and faithful to a latent image, and an image forming method.

It is a further object of the present invention to provide a magnetic toner and an image forming method which are excellent in transferability, have little transfer residual toner, do not cause omission during transfer even in a roller transfer system, or suppress these phenomena. Is to do.

It is a further object of the present invention to provide a magnetic toner and an image for use in an image carrier having excellent releasing properties and excellent slipperiness, and having less of these functions for a long time and after printing a large number of sheets, and having a long service life. It is to provide a forming method.

It is a further object of the present invention to provide a magnetic toner and an image forming method in which a charging abnormality or an image defect due to contamination of a member which is in pressure contact with an electrostatic latent image carrier does not occur or these phenomena are suppressed. It is in.

[0020]

SUMMARY OF THE INVENTION According to the present invention, an electrostatic latent image is formed on an image carrier having a contact angle with water of 90 degrees or more, and the image carrier has a greater thickness than the toner layer thickness on the toner carrier. Magnetic toner used in an image forming method for developing an electrostatic latent image using a developing device in which a closest gap between a toner and a toner carrier is set wide, wherein the magnetic toner contains at least a binder resin and a magnetic material. A magnetic toner obtained by externally adding and mixing toner particles and an inorganic fine powder treated with a compound having an organic group, and a volume average particle diameter D of the toner.
_v ([mu] m) is 3μm ≦ D _v ≦ 8μm, a weight average particle diameter D ₄ (μm) is 3.5μm ≦ D ₄ ≦ 9μm, the ratio M _r of 5μm or smaller particles in the number particle size distribution is 17 Number% ≦ M _r ≦ 90 Number%, the ratio M _r of particles of 5 μm or less in the number particle size distribution and 5 in the volume particle size distribution.
the relationship of the ratio M _v of μm or less of particles _{M r / M v = -0.05M r} + k ( however k =
4.6 to 6.7), and the ratio N _r / N _v ratio N _v of 3.17μm or smaller particles in the ratio N _r and the volume particle size distribution of particles less than 3.17μm in the number particle size distribution is 2. 0 to 8.0.

Further, the present invention provides a developing device in which an electrostatic latent image is formed on an image carrier, and a closest gap between the image carrier and the toner carrier is set to be wider than a toner layer thickness on the toner carrier. In the image forming method for developing an electrostatic latent image by using the toner, the contact angle of water on the surface of the image carrier is 90 degrees or more, and the magnetic toner is composed of at least a binder resin and a magnetic toner particle containing a magnetic material. A magnetic toner obtained by externally adding and mixing an inorganic fine powder treated with a compound having a group, and having a volume average particle diameter _Dv (μm) of 3 μm ≦ _Dv
≦ 8 μm and the weight average particle size D ₄ (μm) is 3.5 μm
m ≦ D ₄ ≦ 9 μm and 5 μm in the number particle size distribution
The ratio M _r of particles having a particle size of m or less is 17 number% ≦ M _r ≦ 90 number%
And the ratio M _r of particles of 5 μm or less in the number particle size distribution and the ratio M _v of particles of 5 μm or less in the volume particle size distribution.
Is M _r / M _v = −0.05 M _r + k (where k =
4.6 to 6.7), and the ratio N _r / N _v ratio N _v of 3.17μm or smaller particles in the ratio N _r and the volume particle size distribution of particles less than 3.17μm in the number particle size distribution is 2. 0 to 8.0.

The magnetic toner and the image forming method of the present invention include:
It has the following advantages.

[0023] A faithful flight of the toner particles to the electrostatic latent image is achieved, and the toner consumption is reduced.

At the transfer site where the transfer material / magnetic toner / electrostatic latent image carrier is present, the toner particles are separated from the electrostatic latent image carrier due to the good releasability of the toner particles from the image carrier. Able to transfer uniformly from the surface to the transfer material.

In the cleaning area where the cleaning blade / transfer residual toner / electrostatic latent image carrier is present, the friction with the photoconductor can be kept low, and as a result, the shaving of the photoconductor is suppressed, and the durability is reduced. Be superior.

According to the present invention having these advantages, high resolution which substantially prevents image contamination, scattering, background fog, and reverse fog when using fine particle toner, which has been a problem in the prior art,
At the same time as obtaining a high-definition image, the scraping of the photoconductor was suppressed, and the life of the electrostatic latent image carrier was extended.

Further, it is preferable that the toner particles also have the particle size distribution of the present invention.

When the number of particles having a particle size of 5 μm or less is 17% by number or less, there is almost no effect on the reduction in consumption, and the volume average particle size D _v (μm) is 8 μm and the weight average particle size D ₄ (μm) is 9 μm. If it exceeds, the resolution of isolated dots of about 100 μm is not sufficient. At this time, if the image is forcibly resolved under development conditions or the like, line thickening or scattering occurs, and the consumption increases. Further, by having the above-mentioned particle size distribution, high productivity is maintained even with a fine particle size toner. Also, 5
If the number of particles of μm or less exceeds 90% by number, the image density is insufficient.

In order to reduce the amount of consumption and to clearly resolve small-diameter isolated dots, the volume average particle diameter D _v (μm) is preferably 3 μm ≦ D _v <6 μm, and the weight average particle diameter D _{v 4} (μm) is 3.5 μm ≦ D ₄ <6.5 μm, and the ratio M _r of particles of 5 μm or less in the number particle size distribution.
Is 60 number% <M _r ≦ 90 number%, the volume ratio of particles of 8 μm or more in the volume particle size distribution is 15 volume% or less, and the ratio N _r of the particles of 3.17 μm or less in the number particle size distribution and the volume particle size the ratio N _r / N _v ratio D _v of the following particles 3.17μm in distribution it is good at 2.0 to 8.0.

More preferably, the particles M having a size of 5 μm or less
_r is 62 number% <M _r ≦ 88 number%, and the average particle diameter is 3.2 μm ≦ D _{v in} order to further improve the resolving power.
≦ 5.8 μm, 3.6 μm ≦ D ₄ ≦ 6.3 μm is good.

In the number particle size distribution, 3.17 μm
The following particle ratio N _r and 3.17 in the volume particle size distribution:
μm the ratio of the ratio N _v of particles below (N _r / N _v), from the viewpoint of image quality, it must be 2.0 to 8.0. 2.0
If it is less than 8.0, fogging will occur.
The resolution of an isolated dot of about 50 μm is deteriorated. The ratio (N _r / N _v) is preferably 3.0 to 7.0. The ratio N _r is preferably 5 to 40% of the particles less than 3.17μm in the number particle size distribution at this time, and more preferably 7-35%.

Further, 8 in the volume particle size distribution of the toner
It is preferable that the volume ratio of the particles having a particle size of μm or more is 10% by volume or less from the viewpoint of further reducing scattering, suppressing a change in the particle size distribution in the developing device through durability, and obtaining a stable concentration.

The toner of the present invention achieves higher image quality due to its small particle size, and has a high charge amount per unit mass.
Achieve low consumption by increasing the amount of fine powder below μm,
A liquid lubricant is included to prevent the image from being caught in the transfer.

Regarding the amount of consumption, generally, the reason why more toner is developed in the line image area than in the solid image area is considered as follows. In the electrostatic latent image of the line image portion on the photoconductor, unlike the solid image portion, the lines of electric force wrap around the line latent image from the outside of the line latent image densely. Is attracted to and pressed against the photoreceptor latent image surface, so that more toner is easily developed on the line latent image surface.

The toner of the present invention contains many particles having a high charge amount of 5 μm or less, and thus easily fills the latent image potential.
Unnecessary toner particles once developed in the line image area on the photoreceptor can return to the sleeve against the force caused by the wraparound of the electric field lines of the latent image, and can be properly applied to the line image area. It is believed that only the amount of toner remains. That is, particles of 5 μm or less reach the latent image on the photoreceptor faster than particles having a larger particle size due to the higher charge amount per unit mass, and wrap around the latent image lines of force to weaken the developing electric field. This is because other particles are less susceptible to the influence of. In addition to this, a large reduction in consumption can be achieved by collecting the transfer residual toner in the developing step.

The magnetic material of the present invention has a magnetic field of 79.6 k
It is preferable that the magnetic material is made of a metal oxide having a magnetization intensity of more than 50 Am ² / kg (emu / g) at A / m (1000 Oe), and includes iron, cobalt, nickel, copper, magnesium, and manganese. And metal oxides containing elements such as aluminum and silicon. These magnetic particles preferably have a BET specific surface area by nitrogen adsorption of 1 to 30 m ² / g, particularly 2.5 to 26 m ² / g,
Further, magnetic powder having a Mohs hardness of 5 to 7 is preferable.

The amount of the magnetic substance is 5 per 100 parts by mass of the binder resin.
The amount is preferably 0 to 200 parts by mass, particularly preferably 60 to 150 parts by mass. If the amount is less than 50 parts by mass, the toner layer on the toner carrier tends to be uneven due to insufficient transportability, resulting in image unevenness, and further, the image density tends to decrease due to an increase in toner tribo. On the other hand, if it exceeds 200 parts by mass, a problem tends to occur in the fixing property.

The average particle size of the magnetic material is 0.05 to 1.
0 μm is preferable, and 0.1 to 0.6 μm is more preferable.
m, more preferably 0.1 to 0.4 μm.

Examples of the type of the binder resin used in the present invention include a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene and a substituted product thereof; styrene-p-chlorostyrene copolymer. Copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene- Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile- Styrene copolymers such as indene copolymers Coalescence; polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin , Polyvinyl butyral, terpene resin, cumarone indene resin, petroleum resin and the like can be used. Further, a crosslinked styrene resin is also a preferable binder resin.

Examples of comonomers for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and the like.
Such as dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. A monocarboxylic acid having a heavy bond or a substituted product thereof;
For example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate, and the like; and vinyl chloride;
Vinyl esters such as vinyl acetate, vinyl benzoate and the like, for example, ethylene olefins such as ethylene, propylene, butylene and the like; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone;
For example, vinyl monomers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; and the like, or a vinyl monomer such as vinyl monomers, may be used alone or in combination. Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene or the like; for example, ethylene glycol diacrylate, ethylene glycol Dimethacrylate,
Carboxylic acid esters having two double bonds such as 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups; Can be used alone or as a mixture.

In the bulk polymerization method, a polymer having a low molecular weight can be obtained by increasing the termination reaction rate by polymerizing at a high temperature, but there is a problem that the reaction is difficult to control. In the solution polymerization method, a low-molecular-weight polymer can be easily obtained under mild conditions by utilizing the difference in radical chain transfer depending on the solvent, and also by adjusting the amount of the initiator and the reaction temperature, and is used in the present invention. It is preferable to obtain a low molecular weight compound in the resin composition.

As the solvent used in the solution polymerization, xylene, toluene, cumene, cellosolve acetate, isopropyl alcohol, benzene and the like are used. In the case of a styrene monomer mixture, xylene, toluene or cumene is preferred. It is appropriately selected depending on the polymer to be polymerized.

Examples of the binder resin for toner used for pressure fixing include low molecular weight polyethylene, low molecular weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, higher fatty acid, polyamide Resins and polyester resins. These are preferably used alone or as a mixture.

It is also preferable to include the following waxes in the toner from the viewpoint of improving the releasability from the fixing member at the time of fixing and improving the fixing property. Paraffin wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, carnauba wax and its derivatives, etc., with derivatives including oxides and block copolymers with vinyl monomers , Graft-modified products.

In addition, alcohols, fatty acids, acid amides,
Esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, animal waxes, mineral waxes, petrolactam and the like can also be used.

As the coloring agent, conventionally known inorganic and organic dyes and pigments can be used. For example, carbon black, aniline black, acetylene black,
Naphthol yellow, Hansa yellow, Lodamn lake, Alizarin lake, Bengala, Phthalocyanine blue, Indaslen blue and the like. These are usually used in an amount of 0.5 to 20 parts by mass based on 100 parts by mass of the binder resin.

In the magnetic toner of the present invention, a charge control agent is blended with toner particles (internal addition) or mixed with toner particles (external addition).
It is preferable to use them. The charge control agent makes it possible to control the amount of charge optimally according to the development system. In particular, in the present invention, the balance between the particle size distribution and the amount of charge can be further stabilized. The following substances control the toner to be negatively charged.

For example, organic metal complexes and chelate compounds are effective, and examples thereof include monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

The following substances are controlled to be positively charged.

Modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and phosphonium salts which are analogs thereof Onium salts such as, for example, these lake pigments, triphenylmethane dyes and these lake pigments (as the lacking agent, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanic acid) , Ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclohexyl Diorgano tin borate such as Suzuboreto; can be used in combination singly or two or more kinds.

The charge control agents described above are preferably used in the form of fine particles. In this case, the number average particle size of these charge control agents is particularly preferably 4 μm or less, more preferably 3 μm or less. When these charge control agents are internally added to the toner, it is preferable to use 0.1 to 20 parts by weight, particularly 0.2 to 10 parts by weight, based on 100 parts by weight of the binder resin.

The magnetic toner of the present invention has environmental stability,
A magnetic toner, which is a feature of the present invention, can be obtained by stirring and mixing an organically treated inorganic fine powder with a mixer such as a Henschel mixer in order to improve charge stability, developability, fluidity, and storage stability.

The inorganic fine powder used in the present invention includes:
For example, the following is used. For example, colloidal silica, titanium oxide, iron oxide, aluminum oxide,
Magnesium oxide, calcium titanate, barium titanate, strontium titanate, magnesium titanate, cerium oxide, zirconium oxide and the like can be used.
These can be used alone or in combination of two or more. Preferably, oxides or double oxides such as titania, alumina and silica are preferred. Particularly, silicic acid fine powder is particularly preferable. For example, as the silicic acid fine powder, both a so-called dry method produced by vapor phase oxidation of a silicon halide or a dry silica called fumed silica, and a so-called wet silica produced from water glass or the like can be used. However, there are few silanol groups on the surface and inside the silica fine powder, and Na ₂ O, SO ₃
Dry silica having a small production residue such as ^2- is more preferable.
In the case of fumed silica, for example, in the manufacturing process,
By using other metal halide compounds such as aluminum chloride, titanium chloride, etc. with silicon halide compounds,
It is also possible to obtain composite fine powders of silica and other metal oxides, and these are included.

The present invention is characterized in that an inorganic fine powder which has been subjected to an organic treatment is used. Examples of such an organic treatment method include a method of treating with an organic metal compound such as a silane coupling agent or a titanium coupling agent that reacts or physically adsorbs with the inorganic fine powder, a method of treating with an silane coupling agent, A method of treating with a coupling agent and treating with an organosilicon compound such as silicone oil at the same time. Examples of the silane coupling agent used for the organic treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, Benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethyl Diethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane,
Hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule, one for each terminal unit And dimethylpolysiloxane containing a hydroxyl group bonded to a silicon atom.

Further, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, Butylaminopropyltrimethoxysilane, dioctylaminopropyldimethoxysilane, dibutylaminopropyldimethoxysilane,
Silane coupling agents such as dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamine, and trimethoxysilyl-γ-propylbenzylamine are also used alone or in combination. Preferred silane coupling agents include hexamethyldisilazane (H
MDS). In addition, examples of the organosilicon compound include silicone oil. Preferred silicone oils have a viscosity at 25 ° C of 0.5 to 10
A substance of 2,000 centistokes, preferably 1 to 1,000 centistokes is used, and for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, fluorine-modified silicone oil and the like are particularly preferable. As a method of the silicone oil treatment, for example, silica fine powder treated with a silane coupling agent and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or silicone fine powder serving as a base may be mixed with silicone fine powder. A method of spraying oil may be used. Alternatively, a method of dissolving or dispersing a silicone oil in an appropriate solvent, adding a silica fine powder, mixing and removing the solvent may be used.

[0056] used in the present invention the organic-treated inorganic fine powder has a specific surface area by nitrogen adsorption measured by BET method is 30 m ² / g or more, in particular 50 to 400 m ² / g good results in the range of The hydrophobic fine particles used in the present invention may be used in an amount of 0.01 to 8 parts by mass, preferably 0.1 to 5 parts by mass, particularly preferably 0.1 to 5 parts by mass, per 100 parts by mass of the toner particles. Preferably, 0.2 to 3 parts by mass is good. If the amount is less than 0.01 part by mass, the effect of improving toner aggregation is poor. If the amount is more than 8 parts by mass, problems such as toner scattering between fine lines, contamination inside the machine, scratches and abrasion of the photoreceptor tend to occur. is there.

The toner used in the present invention is obtained by adding at least an inorganic fine powder to toner particles, and further adding an organic fine powder or a resin fine powder having an average particle diameter smaller than the average particle diameter of the toner particles. This is one of the preferred embodiments.

More specifically, other additives within a range that does not have a substantial adverse effect, such as lubricant powders such as Teflon powder, zinc stearate powder, and polyvinylidene fluoride powder; cerium oxide powder, silicon carbide powder, Abrasives such as strontium titanate powder; fluidity imparting agents such as titanium oxide powder and aluminum oxide powder; anti-caking agents; or conductivity imparting agents such as carbon black powder, zinc oxide powder and tin oxide powder, Organic and inorganic fine particles of opposite polarity can also be used in small amounts as a developer improver.

A known method is used for producing the toner according to the present invention. For example, a binder resin, a wax,
Metal salts or metal complexes, pigments and dyes as colorants,
Alternatively, a magnetic material, a charge control agent, if necessary, and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill, and then melt-kneaded using a heat kneader such as a heating roll, a kneader, or an extruder. A metal compound, a pigment, a dye, and a magnetic substance are dispersed or dissolved in a resin mixed with each other, and after cooling and solidifying, pulverization and classification are performed to obtain the toner according to the present invention. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.

Further, the toner of the present invention may be mixed with carrier particles and used as a two-component toner.

The present invention is effective when the surface of the image carrier is mainly composed of a polymer binder. For example, when a protective film mainly composed of resin is provided on an inorganic image carrier such as selenium or amorphous silicon, or as a charge transport layer of a function-separated organic image carrier, a surface layer composed of a charge transport material and a resin is used. In some cases, a protective layer as described above may be further provided thereon. Means for imparting releasability to such a surface layer include using a resin having a low surface energy as a resin constituting the film, water repellency,
Additives that impart lipophilicity, and powdery materials having high releasability are dispersed. Is achieved by introducing a fluorine-containing group, a silicon-containing group, or the like into the structure of the resin. , A surfactant or the like may be used as an additive. Examples thereof include compounds containing a fluorine atom, that is, powders of polytetrafluoroethylene, polyvinylidene fluoride, carbon fluoride and the like. Among them, polytetrafluoroethylene is particularly preferable. In the present invention, dispersion of a releasable powder such as a fluororesin in the outermost surface layer is particularly preferred.

By these means, the contact angle of water on the surface of the image bearing member can be made 90 degrees or more. If the angle is less than 90 degrees, the toner and the toner carrier are likely to deteriorate due to durability.

In order to incorporate these powders on the surface, a layer in which the powders are dispersed in a binder resin is provided on the outermost surface of the image carrier, or an organic material originally composed mainly of resin. In the case of an image carrier, the powder may be dispersed in the uppermost layer without providing a new surface layer.

The amount of the powder added to the surface layer is preferably 1 to 60% by mass, more preferably 2 to 50% by mass, based on the total mass of the surface layer. When the amount is less than 1% by mass, the effect of improving the durability of the toner and the toner carrier is insufficient, and
Exceeding the range is not preferred because the strength of the film is reduced and the amount of light incident on the image carrier is significantly reduced.

The present invention is particularly effective when the charging means is a direct charging method in which the charging member is brought into contact with the image carrier. As compared with corona discharge or the like in which the charging means does not come into contact with the image carrier, the load on the surface of the image carrier is large, so that the improvement effect is remarkable in terms of the life of the image carrier.

One preferred embodiment of the image carrier used in the present invention will be described below.

Examples of the conductive substrate include metals such as aluminum and stainless steel, aluminum alloys, and indium oxide.
Cylindrical cylinders and films of plastic having a coating layer of a tin oxide alloy or the like, paper impregnated with conductive particles, plastic, plastic having a conductive polymer, and the like are used.

On these conductive substrates, the adhesion of the photosensitive layer is improved, the coating properties are improved, the substrate is protected, defects on the substrate are covered,
An undercoat layer may be provided for the purpose of improving the charge injection property from the substrate, protecting the photosensitive layer against electrical destruction, and the like. The undercoat layer is made of polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymerized nylon, glue,
It is formed of a material such as gelatin, polyurethane, and aluminum oxide. The film thickness is usually 0.1 to 10 μm,
Preferably it is about 0.1 to 3 μm.

The charge generation layer is made of an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone pigment, a squarylium dye, a pyrylium salt, a thiopyrylium salt, a triphenylmethane dye, selenium,
A charge generating substance such as an inorganic substance such as amorphous silicon is dispersed in an appropriate binder and formed by coating or vapor deposition. The binder can be selected from a wide range of binder resins, for example, polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacryl resin, phenol resin, silicone resin, epoxy resin, vinyl acetate resin, etc. Is mentioned. The amount of the binder contained in the charge generation layer is 80% by mass.
Hereinafter, it is preferably selected from 0 to 40% by mass. Further, the thickness of the charge generation layer is preferably 5 μm or less, particularly preferably 0.05 to 2 μm.

The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transporting layer is formed by dissolving a charge transporting substance in a solvent together with a binder resin if necessary, and applying the solution. The film thickness is generally 5 to 40 μm. As the charge transport substance, biphenylene,
Polycyclic aromatic compounds having a structure such as anthracene, pyrene, and phenanthrene; nitrogen-containing cyclic compounds such as indole, carbazole, oxadiazole, and pyrazoline;
Hydrazone compounds, styryl compounds, selenium, selenium
Tellurium, amorphous silicon, cadmium sulfide and the like.

Examples of the binder resin for dispersing these charge transport materials include polycarbonate resin, polyester resin, polymethacrylate, polystyrene resin, and the like.
Examples include resins such as acrylic resins and polyamide resins, and organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene.

Further, a protective layer may be provided as a surface layer. As the resin for the protective layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or a curing agent of these resins alone or
It is used in combination of more than one species.

Further, conductive fine particles may be dispersed in the resin of the protective layer. Examples of the conductive fine particles include metals, metal oxides, etc., preferably, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin oxide-coated titanium oxide, tin-coated indium oxide, There are ultrafine particles such as antimony-coated tin oxide and zirconium oxide. These may be used alone or as a mixture of two or more. Generally, when particles are dispersed in the protective layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles, and the particles are dispersed in the protective layer in the present invention. The particle size of the conductive and insulating particles is preferably 0.5 μm or less. The content in the protective layer is preferably from 2 to 90% by mass, more preferably from 5 to 80% by mass, based on the total weight of the protective layer. The thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 1 to 7 μm.

The coating of the surface layer can be performed by spray coating, beam coating or permeation coating of the resin dispersion.

Hereinafter, the contact transfer step applicable to the image forming method of the present invention will be specifically described.

In the contact transfer step, the developed image is electrostatically transferred onto the transfer material while the transfer means is in contact with the electrostatic image carrier via the transfer material. The contact pressure of the transfer means is a linear pressure. It is preferably at least 2.9 N / m (3 g / cm), more preferably 19.6 N / m (20 g / cm).
That is all. When the linear pressure as the contact pressure is 2.9 N / m (3
g / cm) is not preferred because transfer deviation of the transfer material and transfer failure are likely to occur.

As the transfer means in the contact transfer step, an apparatus having a transfer roller or a transfer belt is used. The transfer roller includes at least a core metal and a conductive elastic layer, and the conductive elastic layer has a volume resistance of 10 ⁶ to 1 such as urethane or EPDM in which a conductive material such as carbon is dispersed.
It is made of an elastic material of about 0 ¹⁰ Ωcm.

The present invention is particularly effectively used in an image forming apparatus in which the surface of a latent image carrier (photoreceptor) is an organic compound. That is, when the organic compound forms the surface layer of the photoreceptor, the adhesiveness to the binder resin contained in the toner particles is superior to other photoreceptors using an inorganic material, and the transferability is further reduced. This is because there is a tendency to do so.

Further, the latent image carrier (photoreceptor) according to the present invention
Examples of the surface material include silicone resin, vinylidene chloride, ethylene-vinyl chloride, styrene-acrylonitrile, styrene-methyl methacrylate, styrene, polyethylene terephthalate, and polycarbonate, but are not limited to other monomers or Copolymers and blends between the aforementioned binder resins can also be used.

The present invention is particularly effectively used for an image forming apparatus having a small-diameter photosensitive member having a diameter of 50 mm or less. That is, in the case of a small-diameter photosensitive member, the curvature for the same linear pressure is large, and the concentration of pressure in the contact portion is likely to occur. Although it is considered that the same phenomenon occurs in the belt photoreceptor, the present invention has a curvature radius of 25 at the transfer portion.
This is also effective for an image forming apparatus having a size of less than mm.

The magnetic toner of the present invention is set so that the closest gap between the image carrier and the toner carrier is larger than the thickness of the toner layer on the toner carrier by a member for regulating the magnetic toner on the toner carrier. It is particularly preferable that the member that regulates the magnetic toner on the toner carrier is regulated by the elastic member that is in contact with the toner carrier via the toner from the viewpoint of uniformly charging the magnetic toner.

The toner carrier for carrying the magnetic toner of the present invention is preferably covered with a resin layer containing conductive fine particles.

The surface roughness of the toner carrier used in the present invention is 0.2 to 0.2 JIS center line average roughness (Ra).
It is preferably in the range of 3.0 μm. Ra is 0.2μ
If it is less than m, the charge amount on the toner carrier increases, and the developability becomes insufficient. When Ra exceeds 3.0 μm, unevenness occurs in the toner coat layer on the toner carrier, resulting in uneven image density.

As the conductive fine particles contained in the resin layer covering the surface of the toner carrier, conductive metal oxides such as carbon black, graphite, and conductive zinc oxide, and metal double oxides may be used alone or in combination of two or more. It is preferably used. Further, as the resin in which the conductive fine particles are dispersed, phenolic resin, epoxy resin, polyamide resin, polyester resin, polycarbonate resin,
Known resins such as polyolefin resins, silicone resins, fluorine resins, styrene resins, and acrylic resins are used. In particular, a thermosetting or photocurable resin is preferable.

The average particle size and particle size distribution of the toner can be measured by various methods such as Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter). In the present invention, Coulter Multisizer (manufactured by Coulter) is used. Is connected to an interface (manufactured by Nikkaki) that outputs the number distribution and volume distribution and a PC9801 personal computer (manufactured by NEC).
A 1% NaCl aqueous solution is prepared using graded sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measurement method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and the measurement sample is added to 2 to 100 ml.
Add ~ 20 mg. The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the volume and number of toner particles having a size of 2 μm or more were measured using the Coulter Multisizer with a 100 μm aperture as an aperture. The number distribution was calculated. Then, the volume-based volume average particle diameter ( _Dv : the median value of each channel is a representative value of the channel) obtained from the volume distribution according to the present invention, the volume variation coefficient ( _Sv ), and the number obtained from the number distribution Reference length average particle diameter (D ₁ ) and length variation coefficient (S ₁ ), mass-based particle ratio (8.00 μm or more and 3.17 μm or less) determined from volume distribution, number determined from number distribution Reference particle ratio (5 μm or less and 3.1
7 μm or less).

In the present invention, the magnetic properties of the magnetic toner were measured using VSM P-1-15 (manufactured by Toei Kogyo Co., Ltd.).
It was determined from the result of measurement at room temperature with an external magnetic field of 79.6 kA / m (1000 Oersted).

The specific surface area was determined by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) according to the BET method, and calculating the specific surface area using the BET multipoint method.

The contact angle of the surface of the image bearing member was measured using pure water, and the apparatus was measured by a contact angle meter CA-Kyowa Interface Science Co., Ltd.
The DS type was used.

Next, the image forming method of the present invention will be specifically described with reference to the drawings.

In FIG. 1, reference numeral 100 denotes a photosensitive drum, around which a primary charging roller 117, a developing device 140, a transfer charging roller 114, a cleaner 116, a register roller 124 and the like are provided. And the photosensitive drum 100
Is charged to -700 V by the primary charging roller 117 (applied voltage is AC voltage -2.0 kVpp, DC voltage -700 Vdc). The photosensitive drum 100 is exposed by irradiating the photosensitive drum 100 with a laser beam 123 by a laser generator 121. The electrostatic latent image on the photosensitive drum 100 is developed with a one-component magnetic toner by a developing device 140,
Transfer roller 1 in contact with photosensitive drum via transfer material
The image is transferred onto a transfer material by. The transfer material bearing the toner image is carried to a fixing device 126 by a conveyor belt 125 or the like, and is fixed on the transfer material. Further, the toner partially left on the electrostatic latent image carrier is cleaned by the cleaning unit 116.

As shown in FIG. 2, the developing device 140 is provided with a cylindrical toner carrier 102 (hereinafter referred to as a developing sleeve) made of a non-magnetic metal such as aluminum or stainless steel in the vicinity of the photosensitive drum 100. The gap between the photosensitive drum 100 and the developing sleeve 102 is maintained at about 300 μm by a sleeve / drum gap holding member (not shown). Further, a stirring rod 141 is provided in the developing device. Inside the developing sleeve, a magnet roller 104 is fixed and disposed concentrically with the developing sleeve 102. However, the developing sleeve 102 is rotatable. The magnet roller 104 is provided with a plurality of magnetic poles as shown in the figure. S ₁ is for development, N ₁ is for controlling the amount of toner coating, S ₂ is for taking in / conveying toner, and N ₂ is for preventing toner blowing. I have. The elastic blade 1 serves as a member for regulating the amount of magnetic toner adhered to and conveyed to the developing sleeve 102.
03 is provided and the developing sleeve 10 of the elastic blade 103 is provided.
The contact pressure with respect to 2 controls the amount of toner conveyed to the development area. In the developing area, a DC and AC developing bias is applied between the photosensitive drum 100 and the developing sleeve 102, and the toner on the developing sleeve flies on the photosensitive drum 100 according to the electrostatic latent image to become a visible image.

[0092]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Production Examples and Examples, but this does not limit the present invention in any way. All parts in the following formulations are parts by mass.

(Production Example 1 of Photoconductor) As a photoconductor, an Al cylinder having a diameter of 30 mm and a diameter of 254 mm was used as a base. Then, layers having the structure shown in FIG. 3 were sequentially laminated by dip coating to prepare a photoreceptor.

(1) Conductive coating layer: mainly composed of tin oxide and titanium oxide powder dispersed in a phenol resin. The thickness is 15 μm.

(2) Subbing layer: mainly composed of modified nylon and copolymerized nylon. The film thickness is 0.6 μm.

(3) Charge generation layer: mainly composed of an azo pigment having absorption in a long wavelength region dispersed in butyral resin. The film thickness is 0.6 μm.

(4) Charge transporting layer: mainly composed of a hole transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight 20,000 according to the Oswald viscosity method) at a mass ratio of 8:10, and further comprising polytetrafluoroethylene. Powder (particle size: 0.2 μm) was added at 10% by mass based on the total solid content, and dispersed uniformly. 25 μm thick. The contact angle with water was 78 degrees.

(Photoreceptor Production Example 2) A photoreceptor was produced in the same manner as in Photoreceptor Production Example 2, except that polytetrafluoroethylene powder was not added. Contact angle to water is 74
Degree.

(Photoreceptor Production Example 3) The photoreceptor was manufactured according to Photoreceptor Production Example 1 up to the charge generation layer. As the charge transport layer, a material obtained by dissolving a hole transporting triphenylamine compound in a polycarbonate resin at a mass ratio of 10:10 was used. Film thickness 20 μm. Further, as a protective layer, a polytetrafluoroethylene powder (particle diameter: 0.2 μm) was added to a composition in which the same material was dissolved at a mass ratio of 5:10.
m) was added to the charge transport layer and spray-coated on the charge transport layer, using 30% of the total solid content and uniformly dispersed. Film thickness 5 μm. The contact angle with water was 102 degrees.

Toner Production Example 1 100 parts of magnetite (average particle size 0.22 μm) styrene-n-butyl acrylate-n-butyl maleate half ester copolymer (copolymerization ratio 77: 20: 3, Mw = 200,000) 100 parts Iron complex of monoazo dye (negative charge control agent) 2 parts Low molecular weight polyolefin (release agent) 3 parts

The above materials were mixed in a blender,
Melted and kneaded with a twin-screw extruder heated to ℃, the cooled kneaded material is roughly pulverized by a hammer mill, the coarsely pulverized material is finely pulverized by a jet mill, and the obtained finely pulverized material is classified by an air classifier. Thus, a black fine powder was obtained. Obtained black fine powder 10
To 0 part, 1.2 parts of hydrophobic silica fine powder (hexamethyldisilazane-treated BET specific surface area: 200 m ² / g) was added, and the mixture was stirred and mixed with a Henschel mixer.
The coarse particles were removed by a mesh sieve to obtain Magnetic Toner A. The weight average particle diameter of the obtained magnetic toner A was 5.0 μm. Table 1 shows the physical properties of the toner.

Toner Production Examples 2 to 7 Fine black powders were obtained in the same manner as in Production Example 1 except that the particle size and the particle size distribution were changed. 1.5 parts of hydrophobic silica fine powder (the same as in Production Example 1) was added to 100 parts of the black fine powder, and magnetic toners B to G were produced in the same manner as in Production Example 1.
I got Table 1 shows the physical properties of the obtained toners B to G.

Toner Production Example 8 Magnetite (average particle size: 0.22 μm) 110 parts Polyester resin 100 parts Iron complex of monoazo dye (negative charge control agent) 2 parts Low molecular weight polyolefin (release agent) 3 parts

Using the above materials, the obtained black fine powder 10
Magnetic toner H was obtained in the same manner as in Toner Production Example 1 except that 1.0 part of hydrophobic silica fine powder (BET specific surface area treated with dimethyl silicone oil: 130 m ² / g) was added to 0 parts. Table 1 shows the physical properties of the obtained magnetic toner H.

Toner Production Example 9 Magnetite (average particle size 0.18 μm) 80 parts Styrene-n-butyl acrylate copolymer (copolymerization ratio 8: 2, Mw = 260,000) 100 parts Chromium complex of monoazo dye (negatively charged) Property control agent) 2 parts Low molecular weight ethylene-propylene copolymer 3 parts

The above components were used in the same manner as in Production Example 1 to obtain a fine black powder. To 100 parts of this black fine powder, 1.2 parts of hydrophobic silica fine powder (the same as in Production Example 1) was added,
Magnetic toner I was obtained in the same manner as in Production Example 1. Table 1 shows the physical properties of the obtained toner I.

[0107]

[Table 1]

Example 1 The image forming apparatus shown in FIG. 1 was generally used.

Using the organic photoconductor (OPC) drum of Photoconductor Production Example 3 as the electrostatic latent image carrier, the dark portion potential V _d = −70.
0 V and the bright portion potential V _L = −210 V. A gap between the photosensitive drum and the developing sleeve is set to 300 μm, and a resin layer having a thickness of about 7 μm and a JIS center line average roughness (Ra) of 0.8 μm having the following structure is used as a toner carrier. A developing sleeve formed on an aluminum cylinder was used, and a urethane rubber blade having a thickness of 1.0 mm and a free length of 10 mm as a toner regulating member was brought into contact with the developing magnetic pole at 950 gauss at a linear pressure of 15 g / cm.

Phenol resin 100 parts Graphite (particle size: about 7 μm) 90 parts Carbon black 10 parts

Next, a DC bias component V _dc = -500 V as a developing bias, and a superimposed AC bias component V
_PP = 1200 V and f = 2000 Hz were used. Also,
The peripheral speed of the developing sleeve is the peripheral speed of the photoconductor (48 mm / sec)
150% speed (72 mm / se
c).

Further, as shown in FIG. 4, a transfer roller (made of ethylene-propylene rubber in which conductive carbon is dispersed, the volume resistivity of the conductive elastic layer is 10 ⁸ Ωcm, and the surface rubber hardness is 24
°, diameter 20 mm, contact pressure 49 N / m (50 g / cm)
Is constant with respect to the peripheral speed of the photoconductor (48 mm / sec),
+2000 V was applied as a transfer bias, and magnetic toner A was used as a toner, and an image was formed under an environment of 23 ° C. and 65% RH. 75 g / m ² paper was used as the transfer paper.

As a result, as shown in Table 2, a good image having sufficient image density and high resolution without any omission during transfer was obtained. The resolution of a 50 μm isolated dot latent image was also at a sufficiently good level.

In this embodiment, the splatter evaluation is a splatter evaluation with fine thin lines related to the quality of a graphical image, and is a splatter evaluation with a 100 μm line which is more easily scattered than a character line. .

The resolving power was evaluated by the reproducibility of a small-diameter isolated dot as shown in FIG.

The transferability is a value obtained by tapping off the transfer residual toner on the solid black photoreceptor with a Mylar tape and peeling off the tape, and then subtracting the Macbeth density of the tape-only tape from the Macbeth density of the tape. The evaluation was very good.

Further, a character pattern of 4% area ratio printing on A4 size paper was continuously printed out for 500 sheets from the beginning, and the toner consumption was determined from the change in the amount of toner in the developing device. The result was 0.025 g / sheet. Met. Further, a latent image of a 10-dot vertical line pattern of 600 dpi (line width: about 420 μm) was written on the photoreceptor at 1 cm intervals by laser exposure, developed, transferred and fixed on a PET OHP. The obtained vertical line pattern image was obtained by using a surface roughness meter surf coder SE-30H (manufactured by Kosaka Laboratory Co., Ltd.) as a method of applying the toner on the vertical line as a surface roughness profile. The width was determined. As a result, the line width was 430 μm, and the lines were reproduced clearly and with high density, and it was confirmed that low consumption was achieved while maintaining the latent image reproducibility.

Further, the image was continuously imaged up to 6000 sheets, and the scraping amount of the photoreceptor was measured with a film thickness meter.
μm, which was very small.

Examples 2 to 5 and Comparative Example 1 Using toners B to F as toners, image formation was performed under the same apparatus and conditions as in Example 1. Table 2 shows the results.

Comparative Example 2 An image was formed using the same apparatus and under the same conditions as in Example 1 except that the toner I was used as the toner and the photoreceptor of Production Example 1 was used as the image carrier. Table 2 shows the results.

COMPARATIVE EXAMPLE 3 Using the photoreceptor of Photoreceptor Production Example 2 as an image carrier, image formation was performed under the same apparatus and conditions as in Example 1. as a result,
Although the resolving power was sufficient, as shown in Table 2, the image was conspicuous with missing characters during character transfer. Further, the shaving amount of the photoreceptor was as large as 3 to 5 μm.

Comparative Examples 4 and 5 Image formation was performed using the same apparatus and conditions as in Example 1 except that toners G and H were used as toners and the photoreceptor of Photoreceptor Production Example 2 was used as an image carrier. Was. As a result, missing characters during character transfer and scattering around the lines were conspicuous, and 100 μm
The resolution of the isolated dot latent image was also insufficient. Furthermore, the consumption was very high as shown in Table 2. Further, the shaving amount of the photoreceptor was as large as 3 to 5 μm.

[0123]

[Table 2]

1) Evaluation of transfer omission ○: Very good △: Slightly present, but practically acceptable ×: Transfer omission is conspicuous and not practical 2) Evaluation of transfer residual rank (4 levels) Transfer residual taping density (tape density Subtracted)
Rank 1: Less than 0.1 Rank 2: 0.1 to less than 0.13 Rank 3: 0.13 to less than 0.16 Rank 4: 0.16 or more

According to the present invention, the magnetic toner having the above-described structure and the image forming method using the same have a high resolution with a good image density with little scraping of the photoreceptor, no omission during transfer and no tailing. It has become possible to obtain images and images with high definition reproducibility.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an image forming apparatus used in the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a diagram illustrating a layer configuration of a photoconductor of Production Example 1 of the present invention.

FIG. 4 is a schematic view of a transfer unit having a transfer roller used in the present invention.

FIG. 5 is a diagram showing a good image (a) without “transfer missing” and a bad image (b) having “transfer missing”.

FIG. 6 is an example of an isolated dot pattern used for resolution evaluation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 photosensitive drum 102 developing sleeve (toner carrier) 103 contact blade 104 magnet roller 114 transfer charging roller 116 cleaner 117 primary charging roller 140 developing device 141 stirring rod 401 photosensitive drum 403 transfer roller 403a core metal 403b conductive elastic layer 414 power supply

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G03G 13/08 G03G 13/08 Z 15/08 507 15/08 507L (56) References JP-A-6-167817 (JP, A JP-A-6-250413 (JP, A) JP-A-2-306274 (JP, A) JP-A-4-162048 (JP, A) JP-A-4-274445 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03G 9/083 G03G 5/05 104 G03G 13/08 G03G 15/08

Claims (17)

(57) [Claims] 1. An electrostatic latent image is formed on an image carrier having a contact angle with water of 90 degrees or more, and the closest gap between the image carrier and the toner carrier is made larger than the thickness of the toner layer on the toner carrier. A magnetic toner used in an image forming method for developing an electrostatic latent image using a developing device set widely, wherein the magnetic toner is treated with a magnetic toner particle containing at least a binder resin and a magnetic material and a compound having an organic group. And a volume average particle diameter _Dv (μm) of 3 μm ≦ _Dv.
≦ 8 μm and the weight average particle size D ₄ (μm) is 3.5 μm
m ≦ D ₄ ≦ 9 μm and 5 μm in the number particle size distribution
The ratio M _r of particles having a particle size of m or less is 17 number% ≦ M _r ≦ 90 number%
And the ratio M _r of particles of 5 μm or less in the number particle size distribution and the ratio M _v of particles of 5 μm or less in the volume particle size distribution.
Is M _r / M _v = −0.05 M _r + k (where k =
4.6 to 6.7) , and the ratio N of particles of 3.17 μm or less in the number particle size distribution.
_r and the ratio of particles of 3.17 μm or less in the volume particle size distribution
Magnetic toner ratio N _r / N _v rate N _v is equal to or is 2.0 to 8.0. 2. A volume average particle diameter D _v (μ
m) is 3 μm ≦ _Dv <6 μm, and the weight average particle diameter D
₄ (μm) is 3.5 μm ≦ D ₄ <6.5 μm, and the ratio M _r of particles of 5 μm or less in the number particle size distribution is 60.
Number% <a M _r ≦ 90% by number, the magnetic toner according to claim 1, volume ratio of 8μm or more particles in the volume particle size distribution is characterized <br /> or less 15% by volume. Wherein the ratio of the ratio N _v of 3.17μm or smaller particles in the ratio N _r and the volume particle size distribution of 3.17μm or smaller particles in the number particle size distribution of the magnetic toner (N _r /
3. The magnetic toner according to claim 1, wherein N _v ) is 3.0 to 7.0, and a volume ratio of particles having a particle size of 8 μm or more in a volume particle size distribution is 10 volume% or less. 4. The method according to claim 1, wherein the inorganic fine powder mixed with the magnetic toner particles is selected from titania, alumina, silica, or a composite oxide thereof. The magnetic toner as described in the above. Surface wherein the inorganic fine particles to be mixed in the magnetic toner particles, the magnetic toner according to any one of claims 1 to 4, characterized in that it is treated with at least silicone for oil. 6. The magnetic toner according to claim 1, wherein the surface of the image carrier is an image carrier containing a lubricating powder containing fluorine. 7. A developing device which forms an electrostatic latent image on an image carrier and uses a developing device in which a closest gap between the image carrier and the toner carrier is set to be wider than a thickness of a toner layer on the toner carrier. In the image forming method for developing a latent image, a contact angle of water on the surface of the image carrier is 90 degrees or more, and the magnetic toner is a compound having an organic group and magnetic toner particles containing at least a binder resin and a magnetic material. And a volume average particle diameter _Dv (μm) of the toner is 3 μm ≦ _Dv.
≦ 8 μm and the weight average particle size D ₄ (μm) is 3.5 μm
m ≦ D ₄ ≦ 9 μm and 5 μm in the number particle size distribution
The ratio M _r of particles having a particle size of m or less is 17 number% ≦ M _r ≦ 90 number%
And the ratio M _r of particles of 5 μm or less in the number particle size distribution and the ratio M _v of particles of 5 μm or less in the volume particle size distribution.
Is M _r / M _v = −0.05 M _r + k (where k =
4.6 to 6.7) , and the ratio N of particles of 3.17 μm or less in the number particle size distribution.
_r and the ratio of particles of 3.17 μm or less in the volume particle size distribution
The image forming method of the ratio N _r / N _v rate N _v is equal to or is 2.0 to 8.0. 8. The volume average particle diameter D _v (μ
m) is 3 μm ≦ _Dv <6 μm, and the weight average particle diameter D
₄ (μm) is 3.5 μm ≦ D ₄ <6.5 μm, and the ratio M _r of particles of 5 μm or less in the number particle size distribution is 60.
Is the number% <M _r ≦ 90% by number, the volume ratio of 8μm or more particles in the volume particle size distribution is not more than 15 vol% <br /> The image forming method according to claim 7, characterized in that. 9. The ratio of the ratio N _v of 3.17μm or smaller particles in the ratio N _r and the volume particle size distribution of 3.17μm or smaller particles in the number particle size distribution of the magnetic toner (N _r /
9. The magnetic toner according to claim 7, wherein N _v ) is 3.0 to 7.0, and a volume ratio of particles having a size of 8 μm or more in a volume particle size distribution is 10 volume% or less. 10. The method according to claim 7, wherein the inorganic fine powder mixed with the magnetic toner particles is selected from titania, alumina, silica, or a double oxide thereof. The image forming method as described in the above. 11. The surface of the inorganic fine particles to be mixed in the magnetic toner particles, the image forming method according to any one of claims 7 to 11, characterized in that it is treated with at least silicone for oil. 12. The image forming method according to claim 7, wherein the surface of the image carrier is an image carrier containing a lubricating powder containing fluorine. 13. The image forming method according to claim 7, wherein the member for regulating the magnetic toner of the toner carrier is in contact with the toner carrier via the toner. . 14. The toner carrier according to claim 7, wherein the toner carrier is covered with a resin layer containing conductive fine particles.
14. The image forming method according to any one of claims 1 to 13. 15. The image forming method according to claim 7, wherein said image bearing member is an organic photoreceptor. 16. The image forming method according to claim 7, wherein the transfer member is in contact with the image carrier via the transfer material during transfer. 17. The image bearing member according to claim 7, wherein a charging member for charging said image bearing member is in contact with said image bearing member.
7. The image forming method according to any one of 6.