JPH08184990A - Magnetic toner and image forming method - Google Patents

Abstract

PURPOSE: To obtain a magnetic toner suppressing the placement of excess toner on a line image while maintaining high image density and latent image reproducibility and with the toner consumption reduced as compared with the conventional toner. CONSTITUTION: A substrate and the coating layer of a toner carrier contain at least a grain to roughen the carrier surface, a conductive substrate and a binder resin. A thin layer of the magnetic toner is formed on the carrier, an AC electric field is impressed on the toner in a developing part, and an electrostatic charge image is developed on the carrier in this image forming method. In this case, the magnetic toner is obtained by externally admixing a magnetic toner grain consisting at least of a binder resin and a magnetic substance and an organically treated inorg. fine powder. Further, the volume average grain diameter Dv (μm)of the toner is limited to conform to 3<=Dv <=6, the weight average diameter D4 (μm) to 3.5<=D4 <=6.5 and the abundance ratio Nm (number %) of <=5μm grains in the number grain size distribution to 60<Nm <=90, where 2<=Nf /Vf <=8 and 5<=Nf <=40.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a number of electrophotographic methods are known, but generally, a photoconductive material is used to form an electric latent image on a photoconductor by various means, and then the electrophotographic image is formed. The latent image is developed with toner to make it a visible image. 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 or pressure to obtain a copy. It is a thing.

In recent years, in addition to conventional copying machines, there have been many printers, facsimile machines, and the like using electrophotographic methods. Particularly in printers and facsimiles, a developing device using a one-component toner is often used because it is necessary to reduce the size of the copying device.

Unlike the two-component system, the one-component developing system does not require carrier particles such as glass beads and iron powder, so that the developing device itself can be made compact and lightweight. Further, since the two-component developing system needs to keep the toner concentration in the carrier constant, a device for detecting the toner concentration and supplying a required amount of toner is required. Therefore, also in this case, the developing device becomes large and heavy. Such a device is not necessary in the one-component developing system, and it is preferable because it can be made small and light.

In addition, LED and LBP printers have become the mainstream of the market in recent years as the printer apparatus, and the direction of technology is higher resolution, that is, 400, 600, 800 dpi instead of 240, 300 dpi in the past. ing. Therefore, the developing system is also required to have higher definition. Further, the copiers are also becoming more sophisticated, and as a result, they are moving toward digitalization. In this direction, the method of forming an electrostatic charge image by a laser is mainly used, and therefore, it is also advancing toward high resolution, and here also, as in the case of a printer, a high resolution / high definition developing method is required. . For this reason, the particle size of the toner is being reduced, and it is disclosed in Japanese Patent Laid-Open Nos. 1-112253 and 1-1.
No. 91156, No. 2-214156, No. 2-284158, No. 3-181952.
Japanese Patent Application Laid-Open No. 4-162048 and Japanese Patent Application Laid-Open No. 4-162048 propose a toner having a specific particle size distribution and a small particle size.

By the way, in the one-component magnetic development method, since the toner is developed in a chain shape (generally called "brush") at the time of development, the resolution in the horizontal direction of the image is worse than that in the vertical direction. For example, the trailing phenomenon due to the protrusion of the ears is likely to occur in the non-image portion in the latter half of the developed image, and a rough image tends to occur as compared with the two-component developing method. Further, the amount of toner on a line having a width of about 400 μm may reach nearly twice the amount of toner on a solid black image. Therefore, as a method of further improving the image reproducibility, it can be considered to make the ears of the magnetic toner shorter and denser. The relationship between the magnetic strength of the magnetic toner and the shape of the spikes is also qualitatively understood as follows. That is, when the magnetic toner has a large magnetization intensity, a strong attractive force along the magnetic field direction and a strong repulsive force in the direction perpendicular to the magnetic field are generated between the magnetic toner particles. Therefore,
When the magnetization intensity is high, the ears formed by the magnetic toner are long and the ears on the toner carrier have a low density and the individual ears are thin. On the other hand, when the magnetic toner has a low magnetization strength, the ears are short and the ears on the toner carrier become dense, but the individual ears are thick because the binding between the magnetic toner particles is not broken. It becomes shorter and becomes aggregated. In this case, the magnetic toner particles existing inside the ears are less likely to come into contact with the surface of the toner carrier, resulting in poor charging. Such poorly charged toner particles cause fog on the image and deteriorate the image quality. That is, as the content of the magnetic material is the same, the finer the toner, the shorter and denser the ears.

Further, when the toner particle size becomes small, the amount of fine powder having a high charge amount increases, and the latent image electric field can be easily filled with a small amount of toner.
A toner having a fine particle size and a large amount of fine powder is particularly excellent in reproducibility of one minute dot of a digital latent image, but tends to have an insufficient image density or a lot of fog. In particular, in printing on a large number of sheets in a low humidity environment, there is a problem that so-called charge-up phenomenon occurs because fine powder easily accumulates on the surface of the toner carrier. This is because the charge amount of the toner coated on the toner carrier becomes too high due to the contact with the toner carrier as the toner carrier repeatedly rotates, and the toner mirrors the surface of the toner carrier. This is a phenomenon in which they are attracted by force, become immobile on the surface of the toner carrier, and do not move from the toner carrier to the latent image on the latent image carrier (drum). When such a phenomenon occurs, the toner in the upper layer is less likely to be charged, and the developing amount of the toner decreases, so that a low-quality image such as a thin line image, a reduced image density of a solid image, or an increase in fog is generated. Become.
Furthermore, since the toner layer forming state of the image portion (toner consuming portion) and the non-image portion are changed, the charging states are different,
The position where a solid image with a high image density is once reached the developing position during the next rotation of the toner carrier, and when a halftone image is developed, a solid image appears behind the image, a so-called toner carrier. Body ghost phenomenon is likely to occur.
Furthermore, in recent years, there has been a tendency to lower the toner fixing temperature for the purpose of shortening the warm-up time and saving the power of the printer body. The toner having such a fine particle diameter and low temperature fixing property is more likely to be electrostatically adhered to the toner carrier, and
Due to the physical force applied from the outside, contamination of the surface of the toner carrier and fusion of the toner are likely to occur.
In addition, with the increasing awareness of resource saving, it is required to further reduce the toner consumption amount (the amount of toner used to form one image).

In recent years, from the viewpoint of environmental protection, the primary charging and transfer processes using corona discharge, which have been conventionally used, are becoming mainstream, and the primary charging and transfer processes using a photoconductor 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 a conductive elastic roller is brought into contact with the electrostatic latent image carrier,
While electrostatically charging the electrostatic latent image carrier while applying a voltage to the conductive roller, another voltage was applied to the electrostatic latent image carrier after obtaining a toner image by exposure and development steps. A transfer material is passed while pressing a conductive roller to transfer the toner image on the electrostatic latent image carrier onto the transfer material, and then a fixing step is performed to obtain a copied image.

However, in such a roller transfer system, since the transfer member is brought into contact with the photoconductor through the transfer member during transfer, the toner image formed on the photoconductor is transferred to the transfer material. The toner image is pressed against the surface, which causes a problem of partial transfer failure, which is so-called void in transfer, and the phenomenon becomes worse as the toner has a finer particle size. These problems are problems that must be improved by all means in order to obtain an image forming apparatus that can obtain high resolution and high definition images at a small size, light weight and low cost while clearing environmental problems.
Satisfaction with all of these issues has not been sufficient with the conventional proposals.

[0011]

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 problems of the prior art.

That is, an object of the present invention is to provide a magnetic toner and an image forming method which consume less toner than ever before.

It is a further object of the present invention that the image density is high,
It is an object of the present invention to provide a magnetic toner and an image forming method capable of faithfully developing a small spot latent image to obtain a sharp image.

A further object of the present invention is to provide a magnetic toner and an image forming method in which the ghost phenomenon of the toner carrier does not occur.

A further object of the present invention is to provide a magnetic toner and an image forming method in which voids during transfer are substantially prevented.

[0016]

The feature of the present invention resides in that the coating layer of the toner carrier having a substrate and a coating layer is provided with particles for imparting roughness to at least the surface of the toner carrier. An image containing a conductive substance and a binder resin, forming a thin layer of magnetic toner on the toner carrier, and developing an electrostatic charge image on the latent image carrier while applying an alternating electric field to the toner in the developing section. In the toner used in the forming method, the magnetic toner is a magnetic toner obtained by externally mixing magnetic toner particles made of at least a binder resin and a magnetic substance, and organically treated inorganic fine powder, and having a volume of the magnetic toner. Particles having an average particle diameter D _v (μm) of 3 ≦ D _v <6, a weight average particle diameter D ₄ (μm) of 3.5 ≦ D ₄ <6.5, and a particle size distribution of 5 μm or less. the existence ratio N _m (% by number) is 60 < a _m ≦ 90, and 2 ≦ N _f / V _f ≦
The magnetic toner and the image forming method are characterized by satisfying 8, 5 ≦ N _f ≦ 40.

Here, N _f represents the number% of magnetic toner of 3.17 μm or less, and V _f represents the volume% of magnetic toner of 3.17 μm or less.

The magnetic toner of the present invention is obtained by adding at least organically treated inorganic fine powder to magnetic toner particles, and in addition, organic fine powder having an average particle size smaller than the average particle size of the toner particles, It also includes resin fine powder and untreated inorganic fine powder added.

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

That is, when the number of particles of 5 μm or less is 60 number% or less, the effect of reducing the consumption is not sufficient, and when the number of particles of 5 μm or less exceeds 90 number%, the image density is insufficient. Preferably, 62% by number <N _m ≤88% by number, and more preferably 64% by number <N _m ≤86% by number.

If the volume average particle size D _v (μm) exceeds 6 μm and the weight average particle size D ₄ (μm) exceeds 6.5 μm, the resolution of isolated dots of small spots is not sufficient. On this occasion,
If an attempt is made to resolve the image under developing conditions, line thickening and toner scattering will occur. Also, the average particle diameter D _v (μm)
Is 6 μm, and the weight average particle diameter D ₄ (μm) is 6.5 μm.
If it exceeds, the effect of reducing the toner consumption is not sufficient. The average particle size of the magnetic toner is preferably 3.2 μm ≦ D _v ≦ 5.8 μm in order to further improve the resolution.
It is preferable that 3.6 μm ≦ D ₄ ≦ 6.3 μm.

Further, in the magnetic toner of the present invention, the number% of particles having a particle size of 3.17 μm or less is
Between (N _f ) and the volume% (V _f ), 2 ≦ N _f / V _f ≦ 5,
One of the characteristics is that the relationship of 5 ≦ N _f ≦ 40 is satisfied. A magnetic toner having a particle size distribution satisfying this range can give particularly excellent resolution to a digital latent image formed from minute spots.

_If the value of N _f / V _f is less than 2, fog tends to occur, and if it exceeds 8, the resolution of minute isolated dots of about 50 μm tends to deteriorate. The value of N _f / V _f is more preferably 3 to 7. When the value of N _f is less than 5, the toner production efficiency tends to deteriorate, and when it exceeds 40, the image density tends to decrease. Range of N _f is more preferably 7 to 35.

When the value of N _f / V _f is in the range of 2 to 8 and N _f is in the range of 5 to 40, good isolated dot resolution of minute spot latent image and good toner consumption are obtained. Amount improvement, sufficient image density, and high durability are achieved.

[0025] N _f / V _f to the value of certain N _f that is large, 3.17Myu from particles greater than 3.17μm
It shows that it contains a wide range of particles up to m.
The fact that N _f / V _f is small indicates that the abundance ratio of particles in the vicinity of 3.17 μm is high. When the N _f / V _f value is in the range of 2 to 8 and N _f is in the range of 5 to 40, good isolated dot resolution of a minute spot latent image, good toner consumption improvement, Sufficient image density and high durability are achieved. Further, the volume ratio V _g (volume%) of particles of 8 μm or more in the volume particle size distribution of the magnetic toner is preferably 10 or less in order to reduce scattering.

The magnetic toner of the present invention achieves higher image quality by having a small particle size, and achieves low consumption by increasing the number of particles having a high charge amount per unit weight of 5 μm or less.

The reason why a larger amount of toner is generally 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 are closely wrapping around the line latent image from the outside of the line latent image. Since a large amount of toner is attracted to and pressed against the photoreceptor latent image surface, more toner is easily developed on the line latent image surface.

The reason why the toner of the present invention is smaller in the amount of toner placed on the line image portion than the conventional toner and the toner consumption amount can be reduced is considered as follows.

In the one-component developing method using a magnetic toner, the toner is developed on the surface of the photoconductor in a state where the toner particles are aggregated to some extent. Since the toner of the present invention contains a large amount of particles having a high charge amount of 5 μm or less, the magnetic force per toner is small, and the latent image potential is easily filled. Therefore, the toner once developed on the line image portion on the photoconductor. It is considered that more than necessary particles can return to the sleeve against the force due to the wraparound of the lines of electric force of the latent image, and only a proper amount of toner remains in the line image portion. That is, particles having a particle size of 5 μm or less reach the latent image on the photoconductor faster than particles having a large particle size because the charge amount per unit weight is high, and the lines of electric force of the latent image wrap around to weaken the developing electric field. This is because other particles are less likely to be affected by. Also in a solid black image,
By reducing the particle size, it is possible to increase the image density with a smaller amount, and it is expected that the consumption will be reduced.

The toner carrier used in the present invention has a cylindrical base material such as aluminum and a coating layer for coating the surface of the base material. FIG. 1 shows the structure of the toner carrier of the present invention. In FIG. 1, the toner carrier 1 has a substrate 5 and a coating layer 6. Further, the coating layer 6 is composed of particles 2 for imparting roughness to the surface of the toner carrier, a binder resin 3 and a conductive substance 4.

The coating layer contains at least particles for imparting roughness to the surface of the toner carrier, a conductive substance, and a binder resin. The size of particles for imparting roughness to the surface of the toner carrier used in the present invention is a number average particle diameter of 0.05 to 100 μm, preferably 0.5 to 50 μm.
Particularly, 1.0 to 20 μm is preferable. If the number average particle size of the particles is less than 0.05 μm, the toner carrying ability is lowered, and
If it exceeds 0 μm, the particles tend to be separated from the coating, which is not preferable. Specific examples of particles that are preferably used in the present invention for imparting roughness to the surface of the toner carrier include PMMA, acrylic resin, polybutadiene resin, polystyrene resin, polyethylene, polypropylene, polybutadiene, and copolymers thereof. Resin particles such as benzoguanamine resin, phenol resin, polyamide resin, nylon, fluorine resin, silicone resin, epoxy resin, polyester resin, or silica, alumina, zinc oxide, titanium oxide, zirconium oxide, calcium carbonate, magnetite, ferrite , Inorganic particles such as glass, and the like. As the particles for imparting roughness to the surface of the toner carrier of the present invention, spherical or nearly spherical particles having the above-described size are particularly preferably used. It is also possible to use a mixture of inorganic particles and organic particles as particles for imparting roughness to the surface of the toner carrier. Of the organic particles, crosslinked resin particles are suitable and preferred. The addition amount of particles for imparting roughness to the surface of the toner carrier in the coating layer used in the present invention is particularly preferably in the range of 2 to 120 parts by weight with respect to 100 parts by weight of the binder resin. . If the amount is less than 2 parts by weight, the effect of adding spherical particles is small and 1
If it exceeds 20 parts by weight, the chargeability of the toner may become too low.

As the conductive substance in the coating layer used in the present invention, carbon black such as furnace black, lamp black, thermal black, acetylene black and channel black; titanium oxide, tin oxide, zinc oxide, molybdenum oxide, titanium. Metal oxides such as potassium acid, antimony oxide and indium oxide; aluminum,
Copper, silver, nickel and other metals, graphite, metal fibers,
An inorganic filler such as carbon fiber may be used. In the present invention,
Particularly, graphite, carbon black or a mixture of graphite and carbon black is particularly preferably used. As the graphite used in the present invention, both a natural product and a synthetic product can be used. It is difficult to unambiguously specify the preferable particle size of graphite due to the fact that the graphite has a scaly shape and that the shape changes during the dispersion step during the production of the toner carrier, but the major axis direction The width (in the direction of the broken surface) is preferably 100 μm or less. As a measuring method, the sample is directly observed with a microscope for measurement. The amount of the conductive substance added to the coating layer used in the present invention is in the range of 10 to 120 parts by weight with respect to 100 parts by weight of the binder resin, and particularly preferable results are obtained. When the amount is more than 120 parts by weight, the film strength and the charge amount of the toner are decreased, and when the amount is less than 10 parts by weight, the toner may be easily contaminated on the surface of the coating layer.

As the binder resin used in the coating layer of the toner carrier of the present invention, generally known resins can be used. For example, styrene resin, vinyl resin, polyether sulfone resin, polycarbonate resin, polyphenylene oxide resin, polyamide resin, fluororesin, fibrous resin, acrylic resin, or other thermoplastic resin,
A heat or light curable resin such as an epoxy resin, a polyester resin, an alkyd resin, a phenol resin, a melamine resin, a polyurethane resin, a urea resin, a silicone resin or a polyimide resin can be used. Above all, it has excellent releasability such as silicone resin and fluororesin, or excellent mechanical properties such as polyether sulfone, polycarbonate, polyphenylene oxide, polyamide, phenol, polyester, polyurethane, styrene resin and acrylic resin. More preferred are: The surface roughness of the conductive coating layer of the toner carrier of the present invention is 0.2 to 4.5 μm, preferably 0.4 to 3.5 μm, as the center line average roughness (Ra hereinafter). If the surface roughness is less than 0.2 μm, the toner transportability may be deteriorated and a sufficient image density may not be obtained, and if it exceeds 4.5 μm, the toner transport amount becomes too large and the toner charging property becomes unsatisfactory. Will be enough. The film thickness of the conductive coating layer is usually preferably 20 μm or less in order to obtain a uniform film thickness, but it is not particularly limited to this film thickness.

The magnetic substance of the magnetic toner used in the present invention includes iron, cobalt, nickel, copper, magnesium,
There are metal oxides containing elements such as manganese, aluminum and silicon. Of these, those containing iron oxide as a main component, such as ferrosoferric oxide and γ-iron oxide, are preferable. From the viewpoint of toner chargeability control, the content of silicon element in the magnetic material is
It is preferably 0.5 to 4 mass% based on the iron element, and more preferably contains silicon atoms on the surface from the viewpoint of toner fluidity. Specifically, the amount of silicon atoms present in the magnetic material up to a iron element dissolution rate of 20% is 1
It is preferably 44 to 84% of the amount of silicon element at the time of 00% dissolution. The silicon atom may be added in the form of a water-soluble silicon compound when the magnetic substance is formed, and after the magnetic substance is formed, filtered and dried,
It may be added in the form of a silicic acid compound and fixed on the surface with a mix muller or the like. These magnetic particles are preferably magnetic powders having a BET specific surface area of ² to 30 m ² / g, especially 3 to 28 m ² / g, and a Mohs hardness of 5 to 7 according to a nitrogen adsorption method.

The shape of the magnetic material is octahedron, hexahedron,
There are spheres, needles, flakes, etc., but those with little anisotropy such as octahedron, hexahedron, sphere, and irregular shape are preferable, and further, the sphericity ψ is 0.8 or more. It is preferable in order to raise. The average particle size of the magnetic substance 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.

The amount of magnetic material is 3 with respect to 100 parts by mass of the binder resin.
0 to 200 parts by mass, preferably 60 to 200 parts by mass, and more preferably 70 to 150 parts by mass. When the amount is less than 30 parts by mass, the transportability is insufficient and unevenness in the developer layer on the developer carrier tends to result in image unevenness, and further, the image density tends to decrease due to the increase in developer tribo. there were. On the other hand, if the amount exceeds 200 parts by mass, the fixing property tends to have a problem.

Examples of the binder resin for the magnetic toner used in the present invention include polystyrene, poly-p-chlorostyrene, a homopolymer of styrene such as polyvinyltoluene and a substitution product thereof; styrene-p-chloro. Styrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer , Styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer -Based copolymer; polyvinyl chloride, phenol resin, natural modified phenol 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, coumarone indene resin, petroleum resin and the like can be used. A crosslinked styrene resin is also a preferable binder resin.

Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate,
Didecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl 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 substituted compounds thereof; for example, vinyl chloride,
Vinyl esters such as vinyl acetate, vinyl benzoate, etc., ethylene-based olefins such as ethylene, propylene, butylene, etc .; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, etc .;
For example, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether and the like; and vinyl monomers such as are used alone or in combination. Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, and examples thereof include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate and ethylene glycol. Dimethacrylate,
A carboxylic acid ester having two double bonds such as 1,3-butanediol dimethacrylate; a divinyl compound such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and a compound having three or more vinyl groups; Can be used alone or as a mixture.

As the binder resin for toner used for pressure fixing, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, higher fatty acid, polyamide Resin and polyester resin may be used. These are preferably used alone or in combination.

Further, it is also preferable to include the following waxes in the toner from the viewpoint of improving the releasability from the fixing member during fixing and 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., where the derivatives are oxides and block copolymers with vinyl monomers. , Including graft modified products.

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

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. The charge control agent makes it possible to control the optimum charge amount according to the developing system, and particularly in the present invention, the balance between the particle size distribution and the charge amount can be further stabilized. The following substances control the toner to be negatively charged.

Organic metal complexes and chelate compounds are effective, for example, monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid 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.

Further, there are the following substances for controlling the positive charge property.

Modified products of 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 and lake pigments thereof, triphenylmethane dyes and lake pigments thereof (as a laker, phosphotungstic acid, phosphomolybdic acid, phosphotungstic molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide) Compounds, ferrocyanides, 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 above charge control agents are preferably used in the form of fine particles. In this case, the number average particle diameter of these charge control agents is 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 mass, particularly 0.2 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

As the coloring material which can be further added to the toner of the present invention, conventionally known carbon stock, copper-phthalocyanine and the like can be used.

Further, the magnetic toner of the present invention has environmental stability,
In order to improve charge stability, developability, fluidity, and storage stability, the inorganic toner finely treated with an organic material is stirred and mixed with a mixer such as a Henschel mixer to obtain the magnetic toner characterized by the present invention.

The inorganic fine powder used in the present invention includes:
Inorganic fine powders such as silicic acid fine powder, titanium oxide, and aluminum oxide are preferable, and silicic acid fine powder is particularly preferable.
For example, both the so-called dry method produced by vapor phase oxidation of a silicon halide or the dry silica called fumed silica and the so-called wet silica produced from water glass can be used as the fine silica powder. But
Dry silica having less silanol groups on the surface and inside the fine silica powder and less production residues such as Na ₂ O and SO ₃ ^2- is preferable. Further, in the case of dry silica, in the manufacturing process, for example, aluminum chloride, titanium chloride,
By using other metal halogen compounds together with the silicon halogen compounds, it is possible to obtain composite fine powders of silica and other metal oxides, and these are also included.

The present invention is characterized by using an organically treated inorganic fine powder. 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 which reacts with or physically adsorbs to the inorganic fine powder, or after treatment with a silane coupling agent, or silane. A method of treating with a coupling agent and at the same time treating with an organic silicon compound such as silicone oil can be mentioned. The silane coupling agent used in the organic treatment, for example, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, Benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethyl Diethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane,
Hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule, one for each terminally located unit And dimethylpolysiloxane containing a hydroxyl group bonded to the silicon atom.

Further, aminopropyltrimethoxysilane having a nitrogen atom, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, mono Butylaminopropyltrimethoxysilane, dioctylaminopropyldimethoxysilane, dibutylaminopropyldimethoxysilane,
A silane coupling agent such as dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamine and trimethoxysilyl-γ-propylbenzylamine may be used alone or in combination. A preferred silane coupling agent is hexamethyldisilazane (H
MDS). In addition, examples of the organic silicon compound include silicone oil. A preferred silicone oil has a viscosity of 0.5 to 10 at 25 ° C.
000 centistokes, preferably 1 to 1000 centistokes are 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 for treating silicone oil, 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 silica fine powder as a base may be treated with silicone. A method of spraying oil may be used. Alternatively, a method may be used in which silicone oil is dissolved or dispersed in a suitable solvent, and then silica fine powder is added and mixed to remove the solvent.

[0052] 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 inorganic fine powder which has been subjected to the hydrophobization treatment and used in the present invention is preferably 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, relative to 100 parts by mass of the toner particles. It is preferably 0.2 to 3 parts by mass. If it is less than 0.01 part by mass, the effect of improving toner aggregation will be poor, and if it exceeds 8 parts by mass, problems such as toner scattering between fine lines, contamination inside the machine, scratches and abrasion of the photoconductor tend to occur. is there.

The magnetic toner of the present invention may further contain other additives within a range that does not have a substantial adverse effect, for example, lubricant powder such as Teflon powder, zinc stearate powder, polyvinylidene fluoride powder; cerium oxide powder and carbonization. Abrasives such as silicon powder and strontium titanate powder; fluidity imparting agents such as titanium oxide powder and aluminum oxide powder;
A small amount of an anti-caking agent or a conductivity-imparting agent such as carbon black powder, zinc oxide powder, tin oxide powder, or organic fine particles and inorganic fine particles having opposite polarities can be used as a developing property 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 as colorants, dyes,
Alternatively, a magnetic material, if necessary, a charge control agent, other additives and the like are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill, and then melt-kneaded by using a heat kneader such as a heating roll, a kneader or an extruder. The metal compound, the pigment, the dye, and the magnetic substance are dispersed or dissolved in the resin to make them compatible with each other, and after solidification by cooling, pulverization and classification are performed to obtain the toner according to the present invention.

The methods for measuring physical properties relating to the present invention will be described below.

(1) Measurement of center line average roughness (Ra) Based on JIS surface roughness (BO601), using a surf coder SE-3300 manufactured by Kosaka Laboratory, 3 points in the axial direction x
Two points in the circumferential direction = 6 points were measured, and the average value was taken.

(2) Particle size measurement of particles for imparting roughness to the surface of the toner carrier. The number was measured using a Coulter LS-130 particle size distribution meter (manufactured by Coulter Co.) of a laser diffraction type particle size distribution meter. The number average diameter obtained from the distribution was determined.

(3) Toner Particle Size Measurement The average particle size and particle size distribution of the toner can be measured by various methods. In the present invention, Coulter Multisizer II (manufactured by Coulter) is used.

The electrolyte is 1% using primary sodium chloride.
An aqueous NaCl solution is prepared. For example, ISOTON R-
II (Made by Coulter Scientific Japan)
Can be used. As a measuring method, the electrolytic aqueous solution 100 is used.
To ˜150 ml, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed by an ultrasonic disperser for about 1 to 3 minutes, and an aperture of 100 μm is obtained by the measuring device.
The volume and number of toner were measured using an aperture to calculate the volume distribution and number distribution. Then, the mass-based weight-average particle diameter obtained from the volume distribution according to the present invention (D ₄ : the median value of each channel is a representative value for each channel), and the volume-based volume-average particle diameter obtained from the volume distribution (D _v : The median value of each channel is a representative value of the channel), the number-based length average particle diameter (D ₁ ) obtained from the number distribution, and the mass-based particle ratio (V _f obtained from the volume distribution). , V _g ), and the number-based particle ratio (N _m , N _f ) determined from the number distribution.

(4) Measurement of BET Specific Surface Area of Magnetic Material The BET specific surface area of the magnetic material according to the present invention was determined by the BET multipoint method using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) by nitrogen adsorption. . As a pretreatment of the sample, deaeration was performed at 50 ° C. for 1 hour.

(5) Calculation of sphericity ψ of magnetic material Further, the sphericity ψ of the magnetic material according to the present invention is calculated as follows.

Sphericality ψ = minimum length of magnetic substance (μm) / maximum length of magnetic substance (μm)

The sphericity ψ was 10 at an applied voltage of 100 kV using a sample of magnetic particles which had been processed into a collodion film copper mesh with a transmission electron microscope (Hitachi H-700H).
It is assumed that 100 magnetic particles are randomly selected from a photograph with a final magnification of 30000 times, the maximum length and the minimum length are measured, and then the average value is calculated. Further, the average particle size is obtained by averaging the maximum lengths of the respective particles by the same method.

(6) Measurement of Magnetic Properties of Magnetic Material The magnetic characteristics of the magnetic material according to the present invention were measured by using a vibrating magnetometer VSM P1-15 (manufactured by Toei Industry Co., Ltd.) in an external magnetic field at room temperature. It is a value measured at 79.6 kA / m (1000 Oersted).

Further, in the magnetic toner of the present invention, the member for regulating the magnetic toner on the toner carrier is regulated by the magnetic member which is in contact with the toner carrier through the toner. It is particularly preferable in terms of

In the present invention, it is preferable in terms of environmental protection that the charging member and the transfer member are in contact with the photoconductor so that ozone is not generated.

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

In FIG. 2, reference numeral 100 is 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 −800V by the primary charging roller 117. Then, the laser light 123 is applied to the photosensitive drum 100 by the laser generator 121, so that the photosensitive drum 100 is exposed. The electrostatic latent image on the photosensitive drum 100 is transferred to the developing device 14
0 is developed with a one-component magnetic toner, and is transferred onto the transfer material by the transfer roller 114 that is in contact with the photosensitive drum via the transfer material (applied DC voltage 2 kV). The transfer material on which the toner image is placed is fixed to the fixing device 1 by the conveyor belt 125 or the like.
It is carried to 26 and fixed on the transfer material. Further, the toner partially left on the electrostatic latent image carrier is cleaned by the cleaning unit 116.
To be cleaned.

As shown in FIG. 3, 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). A stirring rod 141 is arranged in the developing device. A magnet roller 104 is fixed and arranged concentrically with the developing sleeve 102 in the developing sleeve. However, the developing sleeve 102 is rotatable. The magnet roller 104 is provided with a plurality of magnetic poles as shown in the drawing. S ₁ influences development, N ₁ regulates toner coat amount, S ₂ influences toner intake / conveyance, and N ₂ influences toner blowout prevention. There is. The elastic blade 1 is used as a member for controlling the amount of magnetic toner attached to the developing sleeve 102 and conveyed.
03 is arranged and the developing sleeve 10 of the elastic blade 103
The amount of toner conveyed to the developing area is controlled by the contact pressure with respect to 2. In the developing area, a developing bias is applied between the photosensitive drum 100 and the developing sleeve 102, and the toner on the developing sleeve is applied to the photosensitive drum 100 according to the electrostatic latent image.
It flies up and becomes a visible image.

[0070]

EXAMPLES The present invention will be specifically described below with reference to production examples and examples, but the present invention is not limited thereto. In the following formulation, all parts are parts by mass.

(Toner Production Example 1) Magnetic substance (saturation magnetization at 79.6 kA / m σ _s = 63 Am ² / kg, silicon element content rate 1.7%, average particle size 0.22 μm, BET specific surface area 22 m ² / G, sphericity 0.90) 100 parts-Styrene-butyl acrylate-butyl maleate half ester copolymer 100 parts-Iron complex of monoazo dye (negative charge control agent) 2 parts-Low molecular weight polyolefin (release) Agent) 7 parts

The above materials were mixed in a blender, and 130
Melted and kneaded with a twin-screw extruder heated to ℃, cooled and crushed the kneaded material roughly with a hammer mill, finely crushed the coarsely crushed material with a jet mill, and the resulting finely crushed material is multi-divided using the Coanda effect. Strict classification was carried out with a classifier to obtain magnetic toner particles. To the obtained magnetic toner particles, 1.5% by mass of dry silica (BET specific surface area 200 m ^{2 /} g) treated with silicone oil and hexamethyldisilazane was added, and mixed with a Henschel mixer to obtain magnetic toner A. Obtained. The obtained magnetic toner has a weight average particle diameter (D ₄ ) = 5.
5 μm, volume average particle size (D _v ) = 4.8 μm, N _m = 68
Number%, _Vg = 2.1 volume%, and _Nf / _Vf = 5.5. Table 1 shows the physical properties of the obtained toner.

(Toner Production Examples 2 to 3) The coarsely pulverized product obtained in Toner Production Example 1 was pulverized and the classification process was controlled to obtain black fine powder having various particle sizes and particle size distributions. To the obtained black fine powder, 1.3% by mass of dry silica treated in the same manner as in Toner Production Example 1 was added and mixed by a mixer to obtain magnetic toners B and C. Table 1 shows the physical properties of the obtained magnetic toner.

(Toner Production Example 4) Same as Toner Production Example 1 except that 1.8% by mass of dry silica (BET specific surface area 300 m ² / g) treated with silicone oil and hexamethyldisilazane was used as the inorganic fine powder. A magnetic toner D was obtained. Table 1 shows the physical properties of the obtained magnetic toner D.

(Toner Production Example 5) Magnetic substance (saturation magnetization at 79.6 kA / m σ _s = 60 Am ² / kg, silicon element content 3.1%, average particle size 0.24 μm, BET specific surface area 26 m ² / G, sphericity 0.87) 90 parts-Polyester resin 100 parts-Monoazo dye iron complex (negative charge control agent) 2 parts-Low molecular weight polyolefin (release agent) 4 parts

A magnetic toner E was obtained in the same manner as in Toner Production Example 4 except that the above materials were used. Obtained magnetic toner E
The physical properties of are shown in Table 1.

(Toner Production Example 6) In Example 1, dry silica treated with silicone oil and hexamethyldisilazane as the inorganic fine powder (BET specific surface area 200 m
² / g) 1.7% by mass and titania (BET specific surface area 50 m ² / g) treated with silicone oil (0.5% by mass) were mixed and added, and the same procedure as in Toner Production Example 1 was repeated. A magnetic toner F was obtained. Magnetic toner F obtained
The physical properties of are shown in Table 1.

(Toner Production Example 7) In Example 1, 0.3% by mass of alumina (BET specific surface area 100 m ^{2 /} g) treated with silicone oil as the inorganic fine powder, treated with silicone oil and hexamethyldisilazane A magnetic toner G was obtained in the same manner as in Toner Production 1, except that 1.2% by mass of the dry silica (BET specific surface area 200 m ² / g) was mixed and added. Table 1 shows the physical properties of the resulting magnetic toner G.

(Toner Production Example 8) Saturation magnetization at 79.6 kA / m σ _s = 65 Am ² / kg, silicon element content rate 0.3%, average particle size 0.19 μm, BET specific surface area 8 m
^A magnetic toner H was obtained in the same manner as in Toner Production Example 1 except that a magnetic substance having a sphericity of 0.78 / ² / g was used. Table 1 shows the physical properties of the resulting magnetic toner H.

(Toner Production Example 9) Silica treated with dimethyldichlorosilane (BET specific surface area 130 m ² /
A magnetic toner I was obtained in the same manner as in Toner Production Example 1 except that the addition amount of g) was changed to 1.2% by mass. The physical properties of the obtained magnetic toner I are shown in Table 1.

(Toner Comparative Production Examples 1 to 3) The coarsely pulverized products obtained in Toner Production Example 1 were pulverized and the classification process was controlled to obtain black fine powders having various particle sizes and particle size distributions. Dry silica (BET specific surface area 200 m ² / g) treated with 1.3% by mass of hexamethyldisilazane was added to the obtained black fine powder and mixed with a mixer to prepare magnetic toners J, K and L. Got The obtained magnetic toners J, K,
The physical properties of L are shown in Table 1.

[0082]

[Table 1]

[Development Sleeve Production Example 1] Resol type phenol resin solution (containing 50% of methanol) 200 parts Graphite (number average particle size 9 μm) 50 parts Conductive carbon black 5 parts Isopropyl alcohol 130 parts

Zirconia beads having a diameter of 1 mm were added as media particles to the above material, dispersed in a sand mill for 2 hours, and the beads were separated using a sieve to obtain a stock solution. Next, spherical PMMA particles (number average particle size 1
2 μm) and 10 parts of isopropyl alcohol so that the solid content concentration is 30%, and then the diameter is 3 mm.
The glass beads of 1 were dispersed for 1 hour, and the beads were separated using a sieve to obtain a coating liquid.

Using this coating solution, a coating layer was formed on an aluminum cylindrical tube having an outer diameter of 16 mmφ by a spray method, and subsequently, it was heated at 150 ° C. for 30 minutes in a hot air drying oven to be cured to prepare a developing sleeve 1. . The Ra value of the developing sleeve 1 was Ra = 1.9 μm.

[Development Sleeve Production Example 2] Development sleeve production example 1 is the same as development sleeve production example 1 except that spherical PMMA particles (number average particle size 6 μm) are 15 parts. Got 2. The Ra value of the obtained developing sleeve 2 was Ra = 1.4 μm.

[Development Sleeve Production Example 3] The same as in Development Sleeve Production Example 1 except that in the development sleeve Production Example 1, 10 parts of the spherical PMMA particles are 10 parts of spherical nylon resin particles (number average particle diameter 9 μm). Developing sleeve 3
I got The Ra value of the obtained sleeve 3 is Ra = 2.2 μ.
It was m.

[Development Sleeve Production Example 4] The same as in Development Sleeve Production Example 1 except that in the development sleeve Production Example 1, 10 parts of spherical PMMA particles were replaced with 20 parts of spherical phenol resin particles (number average particle size 20 μm). To obtain a developing sleeve 4. The Ra value of the obtained developing sleeve 4 is Ra =
It was 2.7 μm.

[Development sleeve production example 5] In the development sleeve production example 1, 10 parts of spherical PMMA particles were replaced with spherical styrene-diaminoethyl methacrylate-divinylbenzene copolymer particles (copolymerization ratio, 90: 10: 0.1; number). A developing sleeve 5 was obtained in the same manner as in the developing sleeve manufacturing example 1 except that the average particle diameter was set to 15 parts. The Ra value of the obtained developing sleeve 5 was Ra = 2.1 μm.

[Development Sleeve Production Example 6] Resol-type phenol resin solution (containing 50% methanol) 200 parts Graphite (number average particle size 1.5 μm) 30 parts Conductive carbon black 5 parts Isopropyl alcohol 130 parts

Zirconia beads having a diameter of 1 mm were added to the above material as media particles, dispersed in a sand mill for 2 hours, and the beads were separated using a sieve to obtain a stock solution. Next, spherical PMMA particles (number average particle size 1
7 μm) was added in an amount of 10 parts to obtain a developing sleeve 6 in the same manner as in the developing sleeve manufacturing example 1. The Ra value of the obtained developing sleeve 6 was Ra = 2.4 μm.

[Development Sleeve Comparative Production Example 1] In Development Sleeve Production Example 1, a sandblasted aluminum cylindrical tube was used in order to make the surface roughness of the development sleeve coating layer almost equal to that of the development sleeve 1, and a spherical shape was used. P
A developing sleeve 7 was obtained in the same manner as in the developing sleeve manufacturing example 1 except that MMA resin particles were not added. The Ra value of the developing sleeve 7 thus obtained was Ra = 1.9 μm.

[Development Sleeve Comparative Production Example 2] In the development sleeve Production Example 1, graphite (number average particle size 9 μm
A developing sleeve 8 was obtained in the same manner as in the developing sleeve manufacturing example 1 except that m) and the conductive carbon black were removed.
The Ra value of the developing sleeve 8 thus obtained was Ra = 0.7 μm.

[Development Sleeve Comparative Production Example 3] The aluminum cylindrical tube used in Development Sleeve Production Example 1 was subjected to only sandblasting to obtain a development sleeve 9. The Ra value of the developing sleeve 9 thus obtained was Ra = 1.9 μm.

Example 1 An LBP8 Mark IV remodeling machine was used as an evaluation machine, and a rubber roller (diameter 12 mm, contact pressure 50 g / cm) in which conductive carbon coated with nylon resin was dispersed was used as a primary charging roller. , The dark potential V _D = -700 on the electrostatic latent image carrier by laser exposure (600 dpi).
V and the bright portion potential _VL = -200V were formed. The developing sleeve 1 of Sleeve Production Example 1 is used as a toner carrier,
Next, the gap between the photosensitive drum and the developing sleeve 1 (S-D
Distance) to 300 μm, a developing magnetic pole of 800 gauss, a toner regulating member having a thickness of 1.0 mm, and a urethane rubber blade having a free length of 10 mm were brought into contact with each other at a linear pressure of 15 g / cm.
DC bias component V _dc = -500 as developing bias
V, superposed AC bias component V _pp = 1600 V, and frequency 2200 Hz were used.

The magnetic toner A of Toner Production Example 1 was used as the magnetic toner, and further 5000 images were continuously printed under the environment of room temperature of 15 ° C. and humidity of 10% RH. A sufficient solid image density was maintained, and a good image with high resolution without ghost, splattering, or voids was obtained.

Further, under the environment of room temperature of 23 ° C. and humidity of 65% RH, character patterns of 4% printing were continuously printed out on A4 size paper (75 g / m ² ) from the initial 500 sheets, and the amount of toner in the developing device was changed. When the toner consumption amount was calculated from the change, it was 0.032 g / sheet. Furthermore, a latent image of a 10-dot horizontal line of 600 dpi (latent image line width of about 420 μm) is written on the electrostatic latent image carrier by laser exposure at 1 cm intervals, developed, and transferred onto a PET OHP.
Established. The obtained horizontal line pattern image was obtained by using a surface roughness meter Surfcoder SE-30H (manufactured by Kosaka Laboratory) as a profile of the surface roughness of the toner on the horizontal line, and the line width was determined from the width of this profile. It was
As a result, it was confirmed that the line width was 430 μm, the line was reproduced with high density and clearly, and the low consumption was achieved while maintaining the reproducibility of the latent image.

In the present invention, the evaluation of splattering is a splattering evaluation in fine fine lines related to the image quality of a graphical image, and a splattering evaluation in 100 μm, which is easier to scatter than the splattering in a character line.

Further, the resolving power is such that the electric field is easily closed by the latent image electric field, and it is difficult to reproduce, and the small diameter (50 μm) as shown in FIG.
φ) It was evaluated by the reproducibility of isolated dots.

The evaluation of the hollow area is an evaluation when printed on thick paper (about 128 g / m ² ) where the hollow area phenomenon is likely to occur.

The ghost is evaluated by one round of the sleeve at the front end of the printed image (about 50 mm in this embodiment).
The halftone image is developed when the position on the developing sleeve where the image in which the solid white portion and the solid black portion are adjacent to each other within the range of the developing sleeve comes to the developing position when the developing sleeve rotates next time. The difference in light and shade appearing above (the influence of the development history before one rotation of the development sleeve) was visually evaluated.

Comparative Example 1 Toner J of Toner Comparative Production Example 1 was used as the toner, and developing sleeve 7 was used as the developing sleeve, and images were formed in the same manner as in Example 1. As a result, the results shown in Table 2 were obtained, but the images were more consumed than those in Example 1 and were slightly scattered, and the images were slightly hollow and the resolution was inferior.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the developing sleeve 7 was used as the developing sleeve 8 and the toner K of Toner Comparative Manufacturing Example 2 was used as the toner. The results shown in Table 2 were obtained. However, the image density was low and the image was unclear.

Comparative Example 3 In Comparative Example 1, the toner L of Toner Comparative Manufacturing Example 3 is used as the toner, and the developing sleeve 9 is used as the developing sleeve.
When images were printed out in the same manner as in Comparative Example 1 except that the above was used, the results shown in Table 2 were obtained, but the images were unclear with low image density. Further, when the surface of the developing sleeve after the printing test for 5000 sheets was washed and the image was reproduced again, the image density was recovered to 1.35, and it is considered that the sleeve was contaminated by the toner.

Example 2 Image formation was performed using the same apparatus and conditions as in Example 1 except that toner B and developing sleeve 2 were used as toner B and developing sleeve 2, respectively, and good images and consumption were obtained. It was

Example 3 Image formation was performed using the same apparatus and conditions as in Example 1 except that toner C and developing sleeve 3 were used as toner C and developing sleeve 3, respectively, and good images and consumption were obtained. It was Table 2 shows the results.

Example 4 The same procedure as in Example 1 was carried out except that the toner D and the developing sleeve 4 were replaced by the toner D and the developing sleeve 4, respectively. As a result, good images and good consumption were obtained. Table 2 shows the results.

Example 5 The procedure of Example 1 was repeated except that the toner and the developing sleeve were the toner E and the developing sleeve 5, respectively.
Good images and consumption were obtained. Table 2 shows the results.

Example 6 The same operation as in Example 1 was carried out except that the toner F and the developing sleeve 6 were replaced by the toner F and the developing sleeve 6, respectively. As a result, good images and good consumption were obtained. Table 2 shows the results.

Example 7 The same procedure as in Example 1 was carried out except that the toner G was used in Example 1. As a result, the resolution was slightly lowered but the toner consumption was good. Table 2 shows the results.

Examples 8 and 9 Images were produced under the same apparatus and conditions as in Example 1 except that the magnetic toners H and I were used as toners. With magnetic toner I, a slight hollow was observed, but a good image was obtained. Table 2 shows the results.

[0112]

[Table 2]

In the evaluation of scattering, ◯ is extremely good, Δ is good, and X is remarkable.

In the evaluation of resolving power, ○ is extremely good,
△ is good, × is insufficient resolution.

In the evaluation of voids, ○ is extremely good,
Δ is good, and X is markedly hollow.

In the evaluation of the ghost, ◯ is extremely good (no shade difference is observed at all), Δ is good (a slight shade difference is seen, but there is no problem in practical use), and × is noticeable.

[0117]

According to the present invention, by using the magnetic toner and the image forming method having the above-mentioned constitution, it is possible to suppress excessive toner from being applied to the line image while maintaining high image density and latent image reproducibility. It is possible to reduce the toner consumption amount as compared with the conventional one. Further, a high-quality and sharp image can be obtained in which hollow defects and ghosts are prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a toner carrier used in the present invention.

FIG. 2 is an explanatory diagram of an example of an image forming apparatus used in the present invention.

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is an example of an isolated dot pattern used for resolution evaluation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Toner carrier 2 Particles 3 Binder resin 4 Conductive substance 5 Substrate 6 Cover layer 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 Developer 141 stir bar

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location 371 374 (72) Inventor Masayoshi Shimamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Keiji Okano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor, Masashi Ojima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (14)

[Claims] 1. A toner carrier having a substrate and a coating layer, wherein the coating layer contains at least particles for imparting roughness to the surface of the toner carrier, a conductive substance, and a binder resin. In a toner used in an image forming method in which a thin layer of magnetic toner is formed on a body and an electrostatic charge image on a latent image carrier is developed while applying an alternating electric field to the toner in a developing unit, the magnetic toner is at least bound to the toner. A magnetic toner obtained by externally mixing and mixing magnetic toner particles composed of a resin and a magnetic substance and organically treated inorganic fine powder, wherein the volume average particle diameter D _v (μm) of the magnetic toner is 3 ≦ D _v <6. And the weight average particle diameter D ₄
(Μm) is 3.5 ≦ D ₄ <6.5, and the existence ratio N _m (number%) of particles of 5 μm or less in the number particle size distribution.
Is 60 <N _m ≦ 90 and 2 ≦ N _f / V _f ≦ 8,5
A magnetic toner satisfying ≦ N _f ≦ 40.
(N _f represents the number% of the magnetic toner of 3.17 μm or less, and V _f represents the volume% of the magnetic toner of 3.17 μm or less.) 2. The volume particle size distribution of the magnetic toner is 8
The magnetic toner according to claim 1, wherein the abundance ratio V _g (volume%) of particles of μm or more is 10 or less. 3. The magnetic toner according to claim 1 or 2, wherein the inorganic fine powder contained in the magnetic toner is selected from titania, alumina, silica or a complex oxide thereof. 4. The magnetic toner according to claim 1, wherein the inorganic fine powder contained in the magnetic toner is at least treated with silicone oil. 5. The sphericity ψ of the magnetic substance contained in the magnetic toner is 0.8 or more, and the silicon element content is 0.5 to 4 mass% based on the iron element. The magnetic toner according to any one of claims 1 to 4. 6. A toner carrier having a substrate and a coating layer, wherein the coating layer contains at least particles for imparting roughness to the surface of the toner carrier, a conductive substance, and a binder resin. A magnetic toner comprising externally mixed magnetic toner particles composed of at least a binder resin and a magnetic material and organically treated inorganic fine powder on the body, wherein the volume average particle diameter D _v (μm) of the magnetic toner is Is 3 μm ≦ D _v <6, the weight average particle diameter D ₄ (μm) is 3.5 ≦ D ₄ <6.5, and the existence ratio N of particles of 5 μm or less in the number particle size distribution is N.
_m (number%) is 60 <N _m ≦ 90 and 2 ≦ N _f /
Forming a thin layer of the magnetic toner which satisfies _{V f ≦ 8,5 ≦ N f ≦} 40, and wherein developing the electrostatic image on the latent image bearing member while applying an alternating electric field to the toner in the developing unit Image forming method. (N _f represents the number% of the magnetic toner of 3.17 μm or less, and V _f represents the volume% of the magnetic toner of 3.17 μm or less.) 7. The volume particle size distribution of the magnetic toner is 8
The image forming method according to claim 6, wherein the existence ratio V _g (volume%) of particles of μm or more is 10 or less. 8. The image forming method according to claim 6 or 7, wherein the inorganic fine powder contained in the magnetic toner is selected from titania, alumina, silica, or a complex oxide thereof. . 9. The image forming method according to claim 6, wherein the inorganic fine powder contained in the magnetic toner is at least treated with silicone oil. 10. The ψ of the magnetic substance contained in the magnetic toner.
Is 0.8 or more, and the silicon element content rate is 0.5 to 4 mass% based on the iron element. 10. The image forming method according to claim 6, wherein. 11. The image forming method according to claim 6, wherein the particles for imparting roughness to the toner carrier are spherical particles having a number average particle diameter of 0.05 to 100 μm. 12. The image forming method according to claim 6, wherein the conductive material is graphite, carbon black, or a mixture of graphite and carbon black. 13. The image forming method according to claim 6, wherein the electrostatic latent image carrier is an organic photoconductor. 14. The image forming method according to claim 6, wherein a charging member for charging the electrostatic latent image carrier is in contact with the electrostatic latent image carrier.