JP3282015B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming method such as an electrophotographic method and an electrostatic recording method.

[0002]

2. Description of the Related Art Conventionally, many electrophotographic methods are known. In general, a photoconductive substance is used to form an electric latent image on an image carrier (photoreceptor) by various means, and then the latent image is developed with toner to form a visible image. After transferring the toner image onto a transfer material such as paper, the toner image is fixed on the transfer material by heat, pressure or the like to obtain a copy.

In recent years, devices using electrophotography have been increasing in number, such as printers and facsimile machines, in addition to conventional copying machines.

[0004] For example, as a printer device, an LED or LBP printer has become the mainstream in the recent market, and the direction of technology is higher resolution, that is, the conventional 240, 300 printer.
What was dpi is now 400, 600, and 800 dpi. 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 the toner has been reduced, and JP-A-1-112253, JP-A-1-191156, JP-A-2-214156, JP-A-2-284158, and JP-A-3-18.
JP-A-1952 and JP-A-4-162048 propose toners having a specific particle size distribution and a small particle size.

On the other hand, as a developing system, a one-component developing system is preferably used from the viewpoint of reducing the size and weight of printers and facsimile machines. Among them, the toner carrier and the electrostatic latent image carrier are arranged at a certain interval, and a thin toner layer which does not contact the latent image carrier is formed on the toner carrier, and the toner carrier and the latent image carrier are further placed. A jumping development system (Japanese Patent Publication No. 58-32375) in which development is performed by applying an alternating electric field between image carriers is preferably used.

However, even in this developing method, a method of developing toner more faithfully with a latent image on an electrostatic latent image carrier has been studied in order to form an even higher definition image. For example, the direction of reducing the weight per unit area is a method preferably used in the direction of higher definition of image quality, but when the above-described toner having a smaller diameter is used, a solid black density thinner and fogging are observed. At present, a satisfactory image cannot be obtained.

In order to achieve an image forming method capable of forming an image with higher definition than before and an image having a high solid black density and less fog, it is basically desired to improve the fluidity of the toner. .

As one means for ensuring the fluidity of the toner,
JP-A-5-66608, JP-A-4-9860 and the like add an inorganic fine powder which has been subjected to a hydrophobic treatment or an inorganic fine powder which has been subjected to a hydrophobic treatment and further treated with a silicone oil or the like. -249059,
JP-A-4-264453, JP-A-5-34668
In Japanese Patent Application Laid-Open No. 2 (1993) -207, there is known a method in which a hydrophobically treated inorganic fine powder and a silicone oil-treated inorganic fine powder are added together.

However, it has been difficult to maintain the balance between character sharpness, solid black density and fog even when toners using these techniques are used.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method capable of forming an image having sharp solid characters, good solid black density and less fog.

It is another object of the present invention to provide an image forming method which achieves the above object and can form characters without a void.

[0012]

According to the present invention, the above object is achieved by the following constitution.

That is, the present invention provides an image forming method comprising the steps of forming a toner layer on a toner carrier facing an electrostatic latent image carrier and developing an electrostatic latent image on the electrostatic latent image carrier. In the method, the coating amount per unit area of the toner layer formed on the toner carrier is: w / ρ = 0.2 to 0.8 w; the toner coat weight (cm) ρ per 1 cm ^{2 of the} toner carrier surface The center line of the surface of the toner carrier, which is set so as to satisfy the true density of toner (g / cm ³ );
The average roughness Ra is 1.8 μm or less, the toner has at least toner particles and silicic acid fine powder, and the silicic acid fine powder is treated with a silane coupling agent to obtain a bulk density. Is 7
The present invention relates to an image forming method characterized by having a pH of 5.9 to 6.3 at 2 to 165 g / liter.

Regarding the developing method, if w / ρ is smaller than 0.2, solid black density cannot be sufficiently secured, which is not preferable. If w / ρ is larger than 0.8, scattering around the character increases, and a sharp character is not formed, which is not preferable. If the average surface roughness Ra of the toner carrier is larger than 1.8, sharp characters are not formed, which is not preferable. More preferably, Ra is 1.5 or less.
Therefore, it is necessary to have the developing conditions as in the present invention in order to achieve the object of the present invention.

Further, with respect to such a developing condition, the material is treated with a silane coupling agent and has a bulk density of 60 to 180 g / g.
It is necessary to combine a toner containing an inorganic fine powder, which is characterized by a liter and a pH of 4.5 to 8.5.

When the bulk density of the inorganic fine powder is less than 60 g / liter, sufficient fluidity cannot be imparted to the toner, and in the system for thinning the toner layer as in the present invention, the uniformity cannot be obtained. No solid toner coat layer is formed, and a sufficient solid black density cannot be obtained. When the bulk density is more than 180 g / liter, the fluidity of the toner is similarly reduced, and in a thin layer system as in the present invention, a uniform toner coat layer is not formed and a sufficient solid black density can be obtained. Absent.

Further, the pH of the inorganic fine powder added at this time is
Those having a value in the neutral range have a favorable tendency in the sharpness of a character, image density, and missing characters. The toner particles
In general, a charge control agent or a binder resin is designed to have a negative or positive unidirectional chargeability. The mechanism of adding an inorganic fine powder that imparts a charge that excessively increases or decreases the chargeability of the toner in the charging direction is not clear, but it is not particularly clear. In the layer coating type developing method, adverse effects are likely to occur. For example, in the case of a negatively chargeable toner, if the pH is smaller than 4.5, scattering is deteriorated and the sharpness of characters is reduced. If it is larger than 8.5, the solid black density tends to decrease, and the tendency of missing characters in the characters is observed. A more preferably used range is 5.0 to 8.0.

The true density of the toner of the present invention was measured by using a dry automatic densitometer "Acupic 1330" manufactured by Shimadzu Corporation.

The center line average roughness (Ra) is measured based on JIS surface roughness (BO601) using a surface roughness measuring device (Surfcoder SE-30H, Kosaka Laboratory Co., Ltd.). Specifically, the center line roughness (Ra) is obtained by extracting a portion having a measured length a2.5 mm from the roughness curve in the direction of the center line, and setting the center line of the extracted portion to the X axis and the direction of the vertical magnification. When the Y axis and the roughness curve are represented by y = f (x),
The value obtained by the following equation is micrometer (μm)
Refers to what is represented by.

[0020]

(Equation 1)

As the toner carrier used in the present invention, a cylindrical or belt-shaped member made of, for example, stainless steel, aluminum or the like is preferably used. If necessary, the surface may be coated with metal, resin, etc.
A resin in which fine particles such as a resin, metals, carbon black, and a charge controlling agent are dispersed may be coated.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION As the inorganic fine powder used in the present invention, silica, alumina, titania and the like can be used.
In particular, fine silica powder is preferably used as the raw silica before the silane coupling agent treatment.

As the fine silicic acid powder, both a so-called dry method produced by vapor phase oxidation of a silicon halide or a so-called fumed silica and a so-called wet silica produced from water glass or the like can be used. There is
As having less silanol groups on the inner surface and the silica fine powder, also Na ₂ O, SO ₃ ^- it is preferable less dry silica of manufacturing residue such. In the case of fumed silica, it is also possible to obtain a composite fine powder of silica and another metal oxide by using another metal halide such as aluminum chloride and titanium chloride together with a silicon halide in the production process. Is also included.

Examples of the silane coupling agent include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, and benzyldimethylchloro. Silane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethyldiethoxysilane Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3
Divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane and 2 to 12 siloxane units per molecule, the terminal units each containing one hydroxyl group bonded to a silicon atom And dimethylpolysiloxane.

The fine powder is treated with a silane coupling agent by a dry treatment in which a vaporized silane coupling agent is reacted with a cloud of fine powder by stirring or the like, or a silane coupling agent in which the fine powder is dispersed in a solvent. The treatment can be performed by a method such as a wet method in which a ring agent is dropped and reacted. Among them, a dry treatment method is particularly preferably used, but is not limited thereto.

As a method for increasing the bulk density, a mechanical action (Henschel mixer, mix muller, etc.) is performed depending on the reaction conditions when the silicic acid fine powder is formed into a silicon halide or before or after the silane coupling agent treatment. To agglomerate particles with each other.

The inorganic fine powder used in the present invention the specific surface area by nitrogen adsorption measured by BET method 100 m ² / g or more, particularly preferably in the range of 150 to 400 m ² / g.

The inorganic fine powder of the present invention contains toner particles 1
It is preferable to add 0.05 to 3 parts by weight to 00 parts by weight.

In the present invention, the pH is measured using a pH meter using a glass electrode. 4 g of a sample is placed in a beaker, 50 cm ³ of methanol is added to wet the sample, 50 cm ³ of pure water is added, and the mixture is sufficiently stirred with a homomixer. Thereafter, the pH is measured.

The bulk density of the inorganic fine powder of the present invention was measured using a shaking specific gravity measuring device KRS-406 (manufactured by Kuramochi Kaikiki Seisakusho) according to the following procedure.

The powder is put into the attached 150 ml measuring cylinder, and the upper part of the powder is scraped off.

The weight W of the sample placed in the cylinder
Is precisely weighed to 0.01.

Tapping (condition: drop height 6 cm, tapping speed 70 times / min, tapping frequency 1250 times) is performed by a shaking specific gravity measuring instrument, and the powder volume V at that time is read to the 1 ml unit.

The bulk density A is determined by the following equation.

Bulk density A = (W / V) × 1000 (g / liter)

The particle size distribution of the toner used in the present invention is as follows.
When the weight average diameter (D ₄ ) is X (μm) and the number% of 3.17 μm or less based on the number distribution obtained from the number distribution is Y (%), the following conditions are satisfied: −5X + 35 ≦ Y ≦ −25X + 180 3.5 ≦ Those satisfying X ≦ 6.5 are more preferably used to achieve the object of the present invention. Regarding the particle size distribution, Y> −25X + 1
In the case of 80, the fogging phenomenon increases, which is not preferable. Y <
In the case of 5X + 35, the sharpness of the character outline is poor, which is not preferable. If D ₄ <3.5, the image density is undesirably lowered. When D ₄ > 6.5, the sharpness of the character outline is poor and unsatisfactory. The range more preferably used is the case of −5X + 35 ≦ Y ≦ −10X + 80 4.5 ≦ X ≦ 6.5.

The particle size distribution of the toner of the present invention is measured using a Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter Co.), and a 1% aqueous NaCl solution is prepared using primary sodium chloride as an electrolytic solution. 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 dispersing agent to 100 to 150 ml of the electrolytic aqueous solution, and a measurement sample is further added to 2 to 20 ml.
Add 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 measurement apparatus used a 100 μm aperture as a 2 μm aperture.
The volume distribution and the number distribution were calculated by measuring the volume and the number of the toner described above. Then, the weight-average particle diameter (D ₄ : the median value of each channel is a representative value for each channel) obtained from the volume distribution according to the present invention and the number-based weight average particle diameter of 3.17 μm or less obtained from the number distribution The ratio was determined.

The toner of the present invention further contains 20 to 90% by weight (preferably 30 to 80% by weight) of silicone oil or silicone varnish, and has a bulk density of 0.2 to 90%.
0.8 g / ml (preferably 0.25 to 7 g / ml),
The second inorganic fine powder having a specific surface area of 0.01 to 50 m ² / g (preferably 0.5 to 30 m ² / g) is added in an amount of 0.0
It is preferable to appropriately add it in the range of 2 to 1.0 part by weight from the viewpoint of preventing missing characters in a character, fusing of a drum, filming, and the like.

The above silicone oil or silicone varnish has a viscosity at 25 ° C. of 50 to 200,000 centistokes, and more preferably 500 to 150,000 centistokes.
00 centistokes, plus 1,500
-100 to 100,000 centistokes, and more preferably 3,000 to 80,000 centistokes. If it is less than 50 centistokes, it is difficult to form a large amount of silicone oil / silicone varnish into particles, and the particles are not stable, and the image quality tends to deteriorate due to heat and mechanical stress. If it exceeds 200,000 centistokes, it tends to be difficult to form particles.

As the silicone oil used, 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. Examples of the silicone varnish include methyl silicone varnish and phenylmethyl silicone varnish. As a method of silicone oil / silicone varnish treatment, for example, silica fine powder treated with a silane coupling agent and silicone oil / silicone varnish may be directly mixed using a mixer such as a Henschel mixer, or may be mixed with a base. A method of spraying silicone oil / silicone varnish onto the resulting silica fine powder may be used. Alternatively, a method of dissolving or dispersing a silicone oil / silicone varnish in an appropriate solvent, adding silica fine powder, mixing and removing the solvent may be used.

The bulk density of the second inorganic fine powder of the present invention is 5
Drop naturally from the top into a 00 ml container, cut off the part that swells from the container, measure how many g will go into the container,
[G / ml].

More preferably, the toner of the present invention has a third inorganic fine powder. The third inorganic fine powder, by combining with the first and second inorganic fine powder,
The evaluation balance of density, fogging, and hollowing is further improved, and it is also effective in preventing drum fusion. The third inorganic fine powder here is composed of an inorganic compound having the same composition as the first inorganic fine powder of the present invention, and particularly, a fine powder of silica or titanium oxide is preferably used.

Among them, as the third inorganic fine powder, a silica fine powder treated with a silane coupling agent and then treated with a silicone oil or silicone varnish is more preferably used.

The conditions for treating the silica fine powder are as follows: a silane coupling reaction is performed as a first step reaction to eliminate silanol groups by a chemical bond; Characterized by forming a thin film of:

As the silane coupling agent used in the present invention, the same silane coupling agents as those used in the first inorganic fine powder of the present invention can be used.

The method for treating the silane coupling agent is the same as that for the first inorganic fine powder except that the treatment for increasing the bulk density is not performed.

As the substance used for the silicone oil or silicone varnish treatment, the same substance as that used for the second inorganic fine powder may be used. The same method can be used as the treatment method. Among them, a method in which increase in bulk density hardly occurs due to agglomeration of fine powder by the treatment,
For example, a method using a sprayer is preferably used. However, it is not limited to this.

The silane coupling agent may be treated in an amount of 1 to 40 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of the fine powder. The treatment amount of the silicone oil or silicone varnish solid is 1 to 23 parts by weight, preferably 5 to 20 parts by weight, per 100 parts by weight of the fine powder.

If the amount of the silane coupling agent is too small, good solid black density cannot be obtained, and if the amount is too large, problems such as fogging occur. If the amount of the silicone oil or silicone varnish is too small, good solid black density and the effect of improving hollowing out cannot be obtained. If the amount is too large, problems such as fogging occur.

The characteristic values of the treated silica fine powder are as follows:
The bulk density is preferably from 30 to 60 g / l, more preferably from 35 to 55 g / l, from the measurement method used for the first inorganic fine powder of the present invention, and the specific surface area by nitrogen adsorption measured by the BET method is small. is preferably a 80~140m in ² / g range, more preferably 90～130M ²
/ G. It is preferable that the silica fine powder is used in an amount of 0.05 to 1.5 parts by weight, preferably 0 to 1.3 parts by weight, based on 100 parts by weight of the magnetic toner.

The magnetic material used in the toner of the present invention includes metal oxides containing elements such as iron, cobalt, nickel, copper, magnesium, manganese, aluminum and silicon. Among them, those mainly containing iron oxide such as triiron tetroxide and γ-iron oxide are preferable. Further, from the viewpoint of improving the fluidity of the toner and controlling the chargeability, it is preferable to contain a silicon atom. In particular, when the toner particles have a small diameter, the fluidity of the toner particle base is reduced. Therefore, sufficient fluidity cannot be obtained only by adding the inorganic fine powder of the present invention described above, and good chargeability cannot be obtained. It may be difficult to achieve the above objective. The content of silicon atoms is preferably 0.2 to 2.0% by weight based on the magnetic material. If the content is less than 0.2, sufficient fluidity cannot be obtained, and the sharpness of characters deteriorates. Evils such as low solid black density occur. If the content is more than 2.0, the image density tends to decrease particularly in a high temperature and high humidity environment. More preferably, it is 0.3 to 1.7% by weight. In particular, it is more preferable that silicon atoms are present at 0.05 to 0.5% by weight on the surface of the magnetic body.

The silicon atom may be added in the form of a water-soluble silicon compound when the magnetic substance is formed. After the formation of the magnetic substance, filtration and drying, the silicon atom is added in the form of a silicate compound and fixed to the surface with a mix muller or the like. You may. These magnetic particles preferably have a BET specific surface area of 2 to 30 as measured by a nitrogen adsorption method.
m ² / g is good, especially 3~28m ² / g is good. Further, magnetic particles having a Mohs hardness of 5 to 7 are preferred.

The shape of the magnetic particles includes an octahedron, a hexahedron, a sphere, a needle, a scale, and the like, and an octahedron, a hexahedron, a sphere, an irregular shape, or the like having a small anisotropy is preferable.
In particular, it is preferable that the sphericity 磁性 of the magnetic particles be 0.8 or more in order to increase the image density. The average particle diameter of the magnetic particles is preferably 0.05 to 1.0 μm, more preferably 0.1 to 0.6 μm, and particularly preferably 0.1 to 0.4 μm.

The content of the magnetic substance in the toner is 30 to 200 parts by weight, preferably 60 to 200 parts by weight, and more preferably 70 to 150 parts by weight based on 100 parts by weight of the binder resin. If the amount is less than 30 parts by weight, the transportability is inferior, and the toner layer on the developer carrier tends to be uneven, which tends to cause image unevenness, and further, the image density tends to be reduced due to an increase in the tribo of the magnetic toner. was there. On the other hand, when the content of the magnetic substance exceeds 200 parts by weight, there is a tendency that a problem occurs in fixing property.

In the toner for developing an electrostatic image of the present invention, it is preferable to use an organometallic compound as a charge control agent.
Among the organometallic compounds, those containing an organic compound which is particularly highly vaporizable and sublimable as a ligand and a counter ion are useful.

As such a metal complex, there is an azo-based metal complex represented by the following general formula [I].

[0057]

Embedded image

In the formula, M represents a coordination center metal, and Cr, Co, Ni, Mn, Fe, Al, Ti, S
c, V and the like. Ar is an aryl group, such as a phenyl group or a naphthyl group, which may have a substituent. Examples of the substituent in this case include a nitro group, a halogen group, a carboxyl group, an anilide group, an alkyl group having 1 to 18 carbon atoms and an alkoxy group. X, X ', Y,
Y 'is -O-, -CO-, -NH-, -NR- (R is an alkyl group having 1 to 4 carbon atoms). K ⁺ is a hydrogen ion,
It represents a sodium ion, a potassium ion, an ammonium ion, an aliphatic ammonium ion or a mixed ion of any of these.

Hereinafter, specific examples of the complex which is preferably used in the present invention will be shown.

[0060]

Embedded image

[0061]

Embedded image

[0062]

Embedded image

The compound is preferably added in an amount of 0.2 to 5 parts by weight based on 100 parts by weight of the toner.

Examples of the type of the binder resin used in the present invention include polystyrene; styrene-substituted homopolymers such as poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene 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-based copolymers such as styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenolic resin, naturally modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polystyrene Vinyl 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. Also,
Crosslinked styrenic resins are also preferred binder resins.

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 esters having two double bonds such as 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinylether, divinylsulfide, divinylsulfone; and compounds having three or more vinyl groups; Can be used alone or as a mixture.

The binder resin of the toner used for pressure fixing includes low molecular weight polyethylene, low molecular weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-
Examples include acrylate copolymers, higher fatty acids, 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 particles 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.

As other additives, 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.

For preparing the toner of the present invention, a known method is used. For example, a binder resin, a wax, a metal salt or a metal complex, a pigment, a dye, or a magnetic substance as a colorant, a charge control agent, if necessary, and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill. After mixing, melt-knead using a hot kneader such as a heating roll, kneader, or extruder to disperse or disperse the metal compounds, pigments, dyes, and magnetic materials in the resin, and then cool. After solidification, the toner according to the present invention can be obtained by pulverization and classification. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.

An example of the image forming apparatus is schematically shown in FIG. 2, and the image forming method will be described based on the schematic.

Reference numeral 1 denotes a rotating drum-shaped electrostatic latent image carrier, around which a primary charging device 2, an exposure optical system 3, a developing device 4 having a toner carrier 5, a transfer device 9, and a cleaning device 11 are provided. Are located.

In this image forming apparatus, the surface of the electrostatic latent image carrier 1, which is a photosensitive member, is uniformly charged by the primary charging device 2, and the image is exposed to light by the exposure optical system 23. An electrostatic latent image is formed on the surface of the image forming apparatus.

Next, a toner coat layer is formed on the surface of the toner carrier 5 containing a magnet by the toner layer thickness regulating member 6 based on the constitution of the present invention, and the conductive portion of the electrostatic latent image carrier 1 is developed in the developing section. The electrostatic latent image formed on the electrostatic latent image carrier 1 is developed while applying an alternating bias, a pulse bias, and / or a DC bias by the bias applying means 8 between the conductive substrate and the toner carrier 5.

The developed toner image is conveyed to the transfer paper P, and is transferred to the transfer paper P electrostatically by applying a charge having a polarity opposite to that of the toner from the back surface of the transfer paper P by the transfer device 9 and the voltage applying means 10. .

The fixed image is obtained by passing the transfer paper P on which the toner has been transferred through the heating and pressing roller fixing device 12.

The toner remaining on the latent image carrier after the transfer step is removed by the cleaning device 11, and the steps following primary charging are repeated again.

[0077]

EXAMPLES Specific examples of the present invention will be described below. "Department"
Means part by weight.

Example 1 100 parts of binder resin 100 parts of magnetic material (Fe ₃ O ₄ having 0.12% by weight of silicon atom) 100 parts of monoazo dye metal complex (formula a) 2 parts of wax 5 parts

The above constituent materials were mixed and dispersed by a Henschel mixer and melt-kneaded by a twin-screw extruder.
After cooling, the kneaded product was coarsely pulverized, finely pulverized by a pulverizer using a jet stream, and further classified using an air classifier to obtain toner particles.

To 100 parts of the toner particles, 100 parts of original silica (specific surface area = 300 m ² / g) was subjected to coupling treatment with 10 parts of hexamethyldisilazane, and pH = 5.
9. 1.2 parts of inorganic fine powder L-1 having a bulk density of 72 g / liter (specific surface area = 197 m ² / g) was added, mixed with a Henschel mixer, and weight average diameter X = 7.2 (μm), Y
= 5.0 (%) was obtained.

The obtained toner was used as a printer LJ manufactured by HP Co., Ltd.
-IV and evaluated according to the following image evaluation method.

(Production Example of Toner Carrier) Graphite (major axis diameter 4 μm) 100 parts Resole-type phenol resin 200 parts Methanol 130 parts Isobutyl alcohol 160 parts

The above components were dispersed in a sand mill for 2 hours using media particles composed of zirconia beads having a diameter of 1 mm, and the beads were separated using a sieve to obtain a stock solution for coating. Further, this stock solution was diluted with isopropyl alcohol to a solid content of 25% to form a coating solution, and the coating solution having a diameter of 2 was sprayed.
9 μm thick coated on a 0 mm stainless steel carrier base
m of coating is formed, followed by a hot air drying oven at 150 m.
The toner was cured by heating at 30 ° C. for 30 minutes to produce a toner carrier having Ra = 0.8.

An elastic blade made of urethane was brought into contact with the toner carrier thus produced to regulate the toner layer.
The initial coating amount of the thin toner layer on the toner carrier per unit area was 1.1 mg / cm ² , and w / ρ at that time was set to 0.64.

Evaluation of the image quality was carried out in a normal temperature and normal humidity environment (23.
(5 ° C., 60%), the check was periodically performed in the durability of LJ-IV (about 5,000 sheets) and evaluated.

Character sharpness: Using a check sample of 1000 sheets, an approximately 2 mm square “den”
It was magnified 0 times and evaluated according to the following evaluation criteria.

A (excellent): The line is very sharp and almost no scattering occurs. （(Good): The lines are relatively sharp and the lines are relatively sharp. Δ (Normal): The lines are slightly blurred and the lines are blurred. X (bad): less than the level of △.

Solid black density: 20 from initial to 5000 sheets
A total of 26 samples per 0 sheets were measured by a Macbeth densitometer and the average value was shown.

Fog: Using a “Reflectometer” (manufactured by Tokyo Denshoku Co., Ltd.), the whiteness of the transfer paper before printing is measured in advance, and the difference between the whiteness of the printed white image and the whiteness is the largest. Is measured at one point, and the endurance (about 500
(0 sheets).

Character missing: Initially printing 1,000 characters, 2,000 sheets, 3 sheets of general characters on 128 g / m ² thick paper.
The evaluation was made on the average of 6 samples of 000 sheets, 4000 sheets and 5000 sheets. Rank 5: good (see FIG. 1 (a)), rank 1: practically impossible (see FIG. 1 (b)), rank 3:
Practically acceptable, ranks 4 and 2 are intermediate levels between ranks 5 and 3, and ranks 3 and 1, respectively.

Drum fusion: Evaluated from the occurrence of white spots on a solid black image after the end of durability.

◎: not generated, ：: slightly generated,
Δ: Occurs.

Example 2 Evaluation was performed in the same manner as in Example 1 except that the toner particle size was changed. Table 1 shows the results.

Example 3 A second inorganic fine powder obtained by treating 40 parts of M-1 [silica fine powder (110 m ² / g) synthesized by a wet method with 60 parts of dimethyl silicone oil (12500 cSt)]
Evaluation was performed in the same manner as in Example 1 except that a toner to which 0.1 part of a bulk density of 0.4 g / cm ³ and a specific surface area of 3.0 m ² / g was used. Table 1 shows the results.

Example 4 0.8 parts of L-1 and 0.1 part of M-1 as inorganic fine powders and N-1 [raw silica (specific surface area 200 m ² / g) 100 as third inorganic fine powders] 100 parts of fine powder obtained by coupling 10 parts of hexamethyldisilazane with 10 parts of hexamethyldisilazane, treated with dimethyl silicone oil (100 cSt), bulk density 45 g / liter, specific surface area 120 m ² /
g] of Example 1 except that a toner to which 0.7 part of [g] was added was used.
Evaluation was performed in the same manner as described above. Table 1 shows the results.

Example 5 The same conditions as in Example 1 were used except that the developing conditions shown in Table 1 were used using a mirror-finished aluminum tube surface (Ra = 0.3) as the toner carrier. Evaluation was performed by the method. Table 1 shows the results.

Example 6 Evaluation was performed in the same manner as in Example 5, except that 0.1 part of the third inorganic fine powder M-1 was added to the toner. Table 1 shows the results.

Example 7 Evaluation was performed in the same manner as in Example 5 except that a toner in which three kinds of inorganic fine powders were added to the toner as in Example 4 was used. Table 1 shows the results.

Example 8 Toner (X) was prepared in the same manner as in Example 1 except that 1.5 parts of L-2 (pH = 6.3, bulk density = 165 g / l) was added as the first inorganic fine powder. = 5.8 μm, Y = 1
7.5%). Thereafter, evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Example 9 PMMA particles (number average diameter 6.5 μm) were used as a toner carrier.
m) Evaluation was carried out in the same manner as in Example 1 except that a toner carrier having Ra = 1.5 prepared in the same manner as in Example 1 except that 15 parts was further added. However, the toner used was X = 5.8 μm and Y = 17.5%. Thereafter, evaluation was performed in the same manner as in Example 1. Table 1 shows the results
Shown in

Example 10 In the same manner as in Example 1, the toner (X = 5.3 μm, Y =
23%). Thereafter, evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 As a toner carrier, PMMA particles (number average diameter 6.5)
μm) A coating sleeve with Ra = 2.5, prepared in the same manner as in Example 1, except that 25 parts was further added. As the first inorganic fine powder, L-4 [pH = 3.0,
(Bulk density = 35 g / liter) was used, and the toner particle size was X = 7.8 μm and Y = 4.0%. The toner production method and evaluation method were the same as in Example 1. Table 1 shows the results.

Comparative Example 2 The same toner carrier as that used in Example 5 was used as the toner carrier. As the inorganic fine powder, 1.2 parts of L-4 was added, and the toner particle size was X = 5.1 μm and Y = 31.0%. The toner production method and evaluation method were the same as in Example 1. Table 1 shows the results.

[0104]

[Table 1]

[0105]

According to the present invention, it is possible to improve the fluidity of a toner by adding a specific inorganic fine powder, and to impart an appropriate charging property to the toner. The sharpness was good, the solid black density was high, the occurrence of fogging was suppressed, and an image with good character missing was able to be formed.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of a good transfer state (a) and a bad transfer state (b) of a general character.

FIG. 2 is a diagram schematically illustrating an example of an image forming apparatus used in the image forming method of the present invention.

[Description of Signs] 1 latent image carrier 2 primary charging device 3 exposure optical system 4 developing device 5 toner carrier 6 toner layer thickness regulating member 7 toner stirring means 8 developing bias power supply 9 transfer device 10 transfer current generator 11 cleaning Means 12 Fixing device 13 Magnetic toner

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G03G 15/08 504 G03G 9/08 346 507 15/08 507L (56) References JP-A-6-194943 (JP, A) JP-A-6-289723 (JP, A) JP-A-4-162049 (JP, A) JP-A-5-2283 (JP, A) JP-A-63-96665 (JP, A) JP-A-4-50861 (JP JP, A) JP-A-5-80585 (JP, A) JP-A-7-160039 (JP, A) JP-A-6-59501 (JP, A) JP-A-5-119530 (JP, A) JP-A-5-341561 (JP, A) JP-A-7-77830 (JP, A) JP-A-2-306274 (JP, A) JP-A-7-44020 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) G03G 9/08

Claims (10)

(57) [Claims] 1. An image forming method, comprising: forming a toner layer on a toner carrier facing an electrostatic latent image carrier and developing an electrostatic latent image on the electrostatic latent image carrier. The coating amount per unit area of the toner layer formed on the carrier is: w / ρ = 0.2 to 0.8 w; the toner coating weight per 1 cm ^{2 of the} toner carrier surface (mg) ρ; (G / cm ³ ), and the center line of the surface of the toner carrier
The average roughness Ra is 1.8 μm or less. The toner has at least toner particles and silicic acid fine powder, and the silicic acid fine powder is treated with a silane coupling agent, and has a bulk density of 72 to 165 g. PH / 5.9 per liter
To 6.3 . 2. The toner according to claim 1, wherein the particle size distribution is a weight average diameter (D
₄ ) is X (μm), a number standard based on the number distribution obtained from 3.
2. The image forming method according to claim 1, wherein when the number% of 17 μm or less is defined as Y (%), the following condition is satisfied: −5X + 35 ≦ Y ≦ −25X + 180 3.5 ≦ X ≦ 6.5. 3. The image forming method according to claim 1, wherein 0.05 to 3 parts by weight of the inorganic fine powder is added to 100 parts by weight of the toner particles. 4. The toner contains 20 to 90% by weight of silicone oil or silicone varnish, has a bulk density of 0.2 to 0.8 g / ml and a specific surface area of 0.01 to 50 m.
The image forming method according to any one of claims 1 to 3, further comprising a second inorganic fine powder of ² / g. 5. The image forming method according to claim 4, wherein 0.02 to 1 part by weight of a second inorganic fine powder is added to 100 parts by weight of the toner particles. 6. A third inorganic material having a bulk density of 30 to 60 g / l and a specific surface area of 80 to 140 m ² / g, which is treated with a silicone oil or a silicone varnish after the silane coupling agent treatment in the toner. The image forming method according to claim 1, further comprising a fine powder. 7. The image forming method according to claim 6, wherein 0.05 to 3 parts by weight of a third inorganic fine powder is added to 100 parts by weight of the toner particles. 8. The toner according to claim 1, wherein the toner particles contain a magnetic substance, and silicon atoms are contained in an amount of 0.2 to 2.0% by weight based on the magnetic substance. The image forming method according to any one of the above. 9. The toner according to claim 1, wherein the toner particles contain at least a binder resin and a magnetic substance, and the magnetic substance is contained in an amount of 70 to 150 parts by weight based on 100 parts by weight of the binder resin. Item 10. The image forming method according to Item 8. 10. The image forming method according to claim 1, wherein the toner particles contain an organic metal compound represented by the following formula as a charge control agent. Embedded image