JP2782236B2 - Image forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming method using a two-component developer for electrophotography.

[Background Art] As described in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-24748, the electrophotographic method is uniformly applied to a photoreceptor by corona discharge. An electrostatic charge is applied, and a light image corresponding to the document is exposed to thereby extinguish the charge in the exposed portion to form a latent image. The development is carried out by adhering a fine powder test substance, so-called toner, on the obtained electrostatic latent image. The toner is attracted to the electrostatic latent image according to the amount of charge on the photoreceptor, and forms a toner image having density. This toner image is transferred to a support surface such as paper or cloth as necessary, and is permanently fixed to the support surface by using appropriate fixing means such as heating, pressing, solvent treatment, or overcoating.

Various types of developers are conventionally known as electrophotographic developers. Among them, a two-component developer is preferable because a clear image can be obtained as compared with the others. .

In the development of the electrostatic latent image, a two-component developer is used by mixing a toner and a carrier. The composition of both the toner and the carrier is chosen such that the toner has a polarity opposite to the charge on the photoreceptor due to mutual contact friction. As a result of the contact friction between the two, the carrier electrostatically attaches the toner to the surface, transports the developer as a developer in the developing device, and supplies the toner onto the photoconductor.

Examples of the developing method of the developer include a cascade developing method described in U.S. Pat.No. 2,618,552, a magnetic brush method described in U.S. Pat.No. 2,874,063, a touch-down method described in U.S. Pat. J / B development method and the like.

Among them, the magnetic brush method, which is a typical method, uses magnetic particles such as steel and ferrite as a carrier. The developer including the toner and the magnetic carrier is held by a magnet, and the developer is arranged in a brush shape by the magnetic field of the magnet. When the magnetic brush comes into contact with the electrostatic latent image surface on the photoreceptor, only the toner is attracted from the brush to the electrostatic latent image to perform development.

In addition, in the J / B development method, in addition to the magnetic brush method, a bias electric field composed of an AC component and a DC component is applied between the developer carrier and the photoconductor to perform development. Generally, an insulating toner is used. Can be

It is preferable that the image copied by the electrophotographic method is an image which faithfully reproduces an original in which characters and thin lines of a document or a drawing are not blurred, are not thick, exhibit a high density, and have a non-image portion with no image contamination.

In order to obtain a high-quality image, it is essential to improve the resolution, and in recent years, the development of finer toner particles has been promoted. However, as the toner particle size is reduced, the fluidity of the toner tends to decrease and the amount of triboelectric charge tends to increase.
It is well known that a decrease in the fluidity of the toner inhibits rapid triboelectric charging between the toner and the carrier, resulting in fogging and scattering, and a decrease in transferability and cleaning performance.

Conventionally, a cleaning blade made of an elastic material such as urethane rubber has been widely used as a cleaning means because it has a simple structure, is small in size, is advantageous in terms of cost, and has an excellent function of removing residual toner. Is well known.

This type of cleaning blade is made of a suitable elastic material such as urethane rubber, and has a length that covers the entire width of the image area of the photoconductor. One edge of a generally rectangular member is pressed against the photoconductor to remove residual toner on the surface. It is common to configure it to scrape off.

FIG. 1 illustrates a typical mode of use of such a cleaning blade. The cleaning blade (not shown) is mounted on a photosensitive member 1 extending in a direction perpendicular to the paper surface and rotating in the direction of the arrow shown in the drawing. Cleaning blade 2 worn
Are pressed against each other, and one edge of the edge scrapes off residual toner on the surface of the photoreceptor.

However, when a small particle size toner having a volume average particle size of 5 to 10 μm is used, the triboelectric charge amount is higher than that of a toner having a particle size of 10 to 15 μm, so that the adhesive force to the photoreceptor surface is large and the cleaning blade for the residual toner Incomplete scraping, the toner or a portion of the toner that has passed through the pressure-contact edge of the blade, particularly a fluidity improver having a fine particle diameter, is rubbed against the surface of the photoreceptor by the blade-pressure contact force, so that the toner can be fused and adhered. This caused the filming phenomenon.

On the other hand, it can be said that the cause of the filming phenomenon is that the fluidity of the toner is poor. That is, poor fluidity of the toner implies poor dispersibility and adhesion of the fluidity improver, which is one factor of the filming phenomenon, to the surface of the classified product. The fluidity improver or the aggregate of the fluidity improver present alone is electrostatically adhered to the surface of the photoreceptor, and a film is formed by the blade pressing force, resulting in affecting the image.

Further, due to poor fluidity of the toner, the toner scraped off by the cleaning blade may form an aggregate at the press-contact edge portion of the blade, causing a cleaning failure.

The reduction of the particle size of the toner used in the two-component developer is described in Japanese Patent Application Laid-Open Nos. Sho 58-129637 and 59-45452. There is no regulation on the fluidity of the toner, and there is a risk that adverse effects associated with the reduction in toner particle size may occur.

[Problem to be Solved by the Invention] An object of the present invention is to provide an image forming method which has solved the above-mentioned disadvantages.

That is, an object of the present invention is to provide an image forming method capable of obtaining an image which faithfully reproduces an original having a high resolution, a high density and a non-image portion free from image contamination.

Another object of the present invention is to provide an image forming method which does not cause a cleaning failure or a filming phenomenon even with continuous copying of a large number of sheets and causes less image deterioration.

Another object of the present invention is to provide an image forming method in which the photoreceptor is less scraped even after continuous copying.

Means and Solution for Solving the Problems The present invention provides a developing step of forming a toner image by developing an electrostatic latent image formed on an OPC photoreceptor with a two-component developer having a toner and a resin-coated ferrite carrier. An image forming method including: a transfer step of transferring the toner image; and a cleaning step of removing residual toner remaining on the OPC photoconductor after the transfer process by using a cleaning device having an elastic cleaning blade pressed against the OPC photoconductor. In the method, using a photoconductor / cleaning device integrated unit in which an OPC photoconductor is fixed to a part of the cleaning device, a pressure contact force of the cleaning blade against the OPC photoconductor is 25 to 45 g / cm, and the toner is It is composed of at least a colorant-containing resin particle and a fluidity improver, has a volume average particle size of 5 to 10 μm, a fluidity index of 5 to 25%, An image forming method of frictional charge amount of the site carrier characterized in that it is a -15~-35μC / g.

According to the present invention, the volume average particle diameter of the toner used is 5 to 5.
The thickness is 10 μm, preferably 6 to 9 μm. By reducing the particle size of the toner, an image with high resolution and good reproducibility of characters, fine lines, pictures and photographs can be obtained. The triboelectric charge with the resin-coated ferrite carrier is -15 to -35 µC / g, preferably -20 to -30 µC / g. If the triboelectric charge exceeds -35 μC / g, the adhesion of the toner to the photoreceptor is strong, and the function of the cleaning blade to remove the residual toner is significantly reduced. At less than -15 μC / g, good performance is exhibited in terms of cleaning properties, but fog and scattering increase drastically.

Further, according to the present invention, in an electrophotographic copying apparatus using a photoconductor / cleaning device integrated unit for fixing a photoconductor to a part of a cleaning device, a pressing force of the cleaning blade against the photoconductor is 25 to 45 g / cm, preferably 30 to 45 g / cm. 40
g / cm. OPC, whose photoreceptor is weak against friction
In the case of a photoreceptor, it is particularly effective.

Volume average particle size 5 ~ 10μm, triboelectric charge amount -15 ~ -35μC /
When using g toner, if the pressing force exceeds 45 g / cm, the friction between the photoconductor and the blade will increase,
The blade material is deteriorated due to environmental changes or the photoreceptor is scraped, thereby shortening the life of both members. In addition, the blade is easily turned up especially in a high temperature and high humidity environment. On the other hand, if the pressing force is less than 25 g / cm, the scraping of the cleaning blade is remarkably deteriorated, and the fusion of the toner passing through the pressing edge of the blade is induced.

However, even when the copying apparatus and the toner having the above configuration are used, fogging, toner scattering or filming occurs during continuous copying. These causes are due to a decrease in the fluidity of the toner, and can be solved by using the following toner. That is, the fluidity index of the toner used in the present invention is 5 to 25%, preferably 10 to 23%.

The fluidity index in the present invention means that when the fluidity improver is added to a classified product containing at least a resin and a colorant and having a volume average particle diameter of 5 to 10 μm, It is an index of whether the particles are uniformly and strongly adhered to the surface. The smaller the value is, the more strongly the fluidity improver is uniformly adhered and the better the fluidity is. That is, by setting the fluidity index to 5 to 25%, preferably 10 to 23%, the fluidity of the toner is improved, and the amount of the fluidity improver released from the toner surface is drastically reduced. As a result, even during continuous copying, frictional charging between the replenishment toner and the carrier is performed quickly, there is no fogging, scattering, or scattering due to unevenly charged toner or insufficiently charged toner. A clear image can be obtained without filming or fusing of the flowability improver that has slipped through.

 The method for measuring the physical properties of the toner according to the invention is described below.

(1) Using a Coulter Counter TA-II type (manufactured by Coulter) as a particle size measuring device, an interface (manufactured by Nikkaki) that outputs the number average distribution and volume average distribution and a CX-1 personal computer (manufactured by Canon) Connect the electrolyte 1
Prepare a 1% aqueous NaCl solution using graded sodium chloride.

As a measurement method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 0.5 to 50 mg of a measurement sample is further added.

The electrolyte in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the Coulter Counter TA-II was used to measure the particle size distribution of 2 to 40 μm particles using a 100 μm aperture as an aperture. Volume average distribution and number average distribution.

From the obtained volume average distribution and number average distribution, respective values of 5.04 μm or less for the volume average particle diameter and number average distribution and 16.00 μm or more for the volume average distribution are obtained.

(2) The method of measuring the triboelectric charge will be described in detail with reference to the drawings.

FIG. 2 is an explanatory diagram of an apparatus for measuring a triboelectric charge amount of toner. First, a toner and a carrier whose triboelectric charge is to be measured are put into a polyethylene bottle having a capacity of 50 to 100 ml in a metal measuring container 10 having a 500-mesh screen 3 at the bottom, and shaken by hand for about 10 to 40 seconds. Then, about 0.5 to 1.5 g of the mixture (developer) is charged and a metal lid 4 is closed. At this time, the weight of the entire measurement container 10 is weighed and set as W ₁ (g). Next, in the suction device 11 (at least a portion in contact with the measurement container 10 is an insulator), the pressure of the vacuum gauge 5 is adjusted to 250 mmAq by adjusting the air volume control valve 6 by suctioning from the suction port 7. In this state, suction is sufficiently performed, preferably for 2 minutes, to remove the toner by suction. The potential of the electrometer 9 at this time is set to V (volt).
Here, reference numeral 8 denotes a capacitor, whose capacity is C (μF). In addition, the weight of the entire measurement container after suction is weighed and W ₂ (g)
And The triboelectric charge (μC / g) of this toner is calculated as in the following equation.

Sample toner and carrier used for measurement are 23 ℃ and 60% RH
After leaving it for at least 12 hours in the environment, use it for charge measurement.

The measurement of the triboelectric charge is performed in an environment of 23 ° C. and 60% RH.

(3) Fluidity index There are various types of fluidity measurement conventionally known. For example, there are a repose angle, a degree of compression, a spatula angle, a uniformity, a degree of cohesion, etc. measured using a powder tester (manufactured by Hosokawa Micron Corporation). No difference in measured values
Not suitable.

The toner of the present invention is measured by a conventional measuring method (powder tester,
(Aggregation degree) and values measured by the measurement method of the present invention are shown below.

Therefore, the fluidity index of the toner according to the present invention can be calculated using a conventionally known powder tester (manufactured by Hosokawa Micron Corporation).
(PT-D type) according to the following method. The measurement environment is 23 ° C and 60% RH.

(1) Leave the toner in the measuring environment for 12 hours and accurately measure 5.0 g.

(2) On the shaking table, 100 mesh from above (150μ mesh)
m) Sieves of 200 mesh (mesh size: 75 μm) and 400 mesh (mesh size: 38 μm) are stacked and set.

(3) Place 5.0 g of precisely weighed toner on a sieve (on 100 mesh) gently, and vibrate for 15 seconds with a shaking width of 1 mm.

(4) Gently weigh the amount of toner remaining on each sieve.

In order to obtain a toner having a fluidity index of 5 to 25%, a classified product having a volume average particle size of 5 to 10 μm, preferably 6 to 9 μm, the amount and type of the fluidity improver, and the type of mixer It can be achieved by appropriately selecting and combining the four factors of the mixing conditions.

Examples of the mixing machine include a rotary blender, a container drum mixer, a turbula mixer, a V-type blender, a double cone blender, a ribbon type blender, a paddle type blender, a vertical ribbon type blender, a Nauta mixer, a Henschel mixer, a micro mixer. A speed mixer, a flow jet mixer or the like can be used as appropriate.

The fluidity improver used in the present invention includes, for example, fluorine resin powders, that is, vinylidene fluoride fine powder, polytetrafluoroethylene fine powder, and the like; or fatty acid metal salts, that is, zinc stearate, calcium stearate, lead stearate, and the like. Or metal oxides, such as zinc oxide powder; or finely divided silica, ie, silica produced by a wet process, dry process, or a silica obtained by subjecting the silica to a surface treatment with a silane coupling agent, a titanium coupling agent, silicon oil, or the like. and so on.

Preferred fluidity improvers are fine powders produced by the vapor phase oxidation of silicon halide compounds, so-called dry silica or fumed silica, which is produced by a conventionally known technique. . For example, it utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows.

SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl Also, in this manufacturing process, by using another metal halide such as aluminum chloride or titanium chloride together with a silicon halide, a composite fine powder of silica and another metal oxide is obtained. Is also possible and encompasses them.

The particle size is preferably in the range of 0.001 to 2 μm as an average primary particle size, and particularly preferably 0.002 to 2 μm.
It is preferable to use silica fine powder in the range of 0.2 μm.

Commercially available fine silica powder produced by vapor phase oxidation of a silicon halide used in the present invention includes, for example, those commercially available under the following trade names.

AEROSIL 130 (Nippon Aerosil) 200 300 380 TT600 MOX170 MOX 80 COK 84 Ca-O-SiL M-5 (CABOT Co.) MS-7 MS-75 HS-5 EH-5 Wacker HDK N20 V15 (WACKER- CHEMIE GMBH) N20E T30 T40 DC Fine Silica (Dow Corning Co.) Fransol (Fransil) Further, treated silica fine powder obtained by hydrophobizing silica fine powder generated by gas phase oxidation of the silicon halide. More preferably, the body is used. It is particularly preferable that the treated silica fine powder is obtained by treating the silica fine powder such that the degree of hydrophobicity measured by a methanol titration test shows a value in the range of 30 to 80.

Hydrophobizing is applied by reacting with silica fine powder or chemically treating with an organic silicon compound or the like which physically adsorbs.

As a preferred method, silica fine powder produced by vapor phase oxidation of a silicon halide is treated with an organosilicon compound.

Examples of such organosilicon compounds are hexamethyldisilazane, trimethylsilane, trimethylchlorosilane,
Trimethylethoxysilane, dimethyldichlorosilane,
Methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α
-Chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane,
Triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane,
Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane and 2 to 12 siloxane units per molecule with terminal positions For example, dimethylpolysiloxane containing a hydroxyl group bonded to one Si unit may be used for each unit. These are used alone or as a mixture of two or more.

The particle size of the treated silica fine powder is 0.003-0.1μm
It is preferable to use those in the range of Commercial products include Taranox-500 (Talco), AEROSIL R-972
(Nippon Aerosil).

If necessary, the fluidity improver may be crushed in advance by a pulverizer, and then mixed and dispersed with a classified product using a Henschel mixer or the like.

As the binder resin to be applied to the toner of the present invention, all known resins can be used. For example, polystyrene, poly-p-chlorostyrene, homopolymers of styrene such as polyvinyltoluene and its substituted products, styrene-p-chloroform Styrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethacrylic acid Methyl copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer Styrene-based copolymers such as polymers, styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, styrene-maleic acid ester copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, and polyacetic acid Vinyl, poly Tylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorination Paraffin, paraffin wax and the like can be used alone or in combination.

Particularly preferred resins for the practice of the present invention include styrene-acrylate resins and polyester resins.

In particular, (Wherein R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2
~ 10. A) a carboxylic acid component composed of a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid) An acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) is more preferable because it has sharp melting characteristics.

As the coloring agent used in the present invention, as the dye,
For example, CI Direct Red 1, CI Direct Red 4, CI Acid Red 1, CI Basic Red 1,
CI Modern Red 30, CI Direct Blue 1, C.
I. Direct Blue 2, CI Acid Blue 9, CI Acid Blue 15, CI Basic Blue 3, CI Basic Blue 5, CI Modern Blue 7, and the like.

Pigments include carbon black, naphthol yellow S, Hanza yellow G, permanent yellow NCG,
Permanent Orange GTR, Pyrazolone Orange, Benzidine Orange G, Permanent Red 4R, Watching Red Calcium Salt, Brilliant Carmine 3B, Fast Violet B, Methyl Piolet Lake, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue BC and the like.

Preferably, the pigment is furnace black, disazo yellow, insoluble azo, copper phthalocyanine, and the dye is a basic dye or an oil-soluble dye.

Particularly preferably, CI Pigment Yellow 17, CI Pigment Yellow 15, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 12, CI
Pigment Red 5, CI Pigment Red 3, CI Pigment Red 2, CI Pigment Red 6, CI Pigment Red 7, CI Pigment Blue 15, CI Pigment Blue 16, and the like.

Dyes include CI Solvent Red 49, CI Solvent Red 52, CI Solvent Red 109, CI Basic Red 12, CI Basic Red 1, and CI Basic Red 3b.

It is also preferable that the toner according to the present invention contains a charge control agent in order to stabilize the negative charge characteristics. At that time, a colorless or light-colored negative charge control agent which does not affect the color tone of the toner is preferable. Examples of the negative charge control agent include an organic metal complex such as a metal complex of an alkyl-substituted salicylic acid (for example, a chromium complex or a zinc complex of di-tert-butyl salicylic acid). When a negative charge control agent is blended in the toner, 0.1 to 100 parts by weight of the binder resin is used.
It is preferable to add 10 parts by weight, preferably 0.5 to 8 parts by weight.

In a general method for producing the toner of the present invention, first, a resin and a colorant (charge control agent in some cases) are uniformly dispersed by a Henschel mixer or the like, and then melt-kneaded by a kneader, an extruder, a roll mill, or the like. Next, the kneaded material is roughly pulverized by a cutter mill, a hammer mill or the like, and further finely pulverized by a jet mill, an I-type mill or the like. The finely pulverized material is classified using a DS, a zigzag classifier, and an elbow jet classifier, and the fluidity improver is dispersed in the classified product using a Hanger gel mixer or the like.

As the resin-coated ferrite carrier used in the present invention, conventionally known ones can be used, but copper-zinc-iron-based ferrite particles are used as a core material, and a fluororesin-styrenic resin such as vinylidene fluoride-tetra Fluoroethylene copolymer and styrene-acrylic acid 2
Those using a mixture of -ethylhexyl-methyl methacrylate are particularly preferred.

The average particle size of these carriers is 20 to 100 μm, preferably 2 to 100 μm.
It preferably has a thickness of 5 to 70 μm, more preferably 30 to 65 μm. When a two-component developer is prepared by mixing with a toner, the mixing ratio is preferably 2% by weight to 10% by weight, and more preferably 3% by weight to 8% by weight, as a toner concentration in the developer. can get. If the toner concentration is less than 2%, the image density is low and it becomes impractical. If it exceeds 10%, fog and scattering inside the machine are increased, and the useful life of the developer is shortened.

 Hereinafter, the present invention will be described in detail with reference to Examples.

[Example] Example 1 Each of the above formulations was premixed with a Henschel mixer and melt-kneaded with a roll mill. After cooling, the mixture was roughly pulverized to 1 to 2 nm by a hammer mill and finely pulverized by a jet mill. The finely pulverized product was classified by an Elpojet classifier to obtain a classified product having a volume average particle size of 8.1 μm.

To 100 parts by weight of the classified product, 0.7 part by weight of silica fine powder treated with a flowability improver hexamethyldisilazane was mixed and dispersed by a Henschel mixer for 3 minutes to obtain a toner having a flowability index of 15%.

FIG. 3 shows the relationship between the mixing time of the Henschel mixer and the fluidity index at this time.

As a carrier, Cu-Zn-Fe-based ferrite particles were used as a core material, and styrene, 2-ethylhexyl acrylate, and methyl methacrylate were used as coating materials.

The triboelectric charge of 5 parts by weight of the toner and 95 parts by weight of the carrier was −25.3 μC / g, and a mixture obtained by mixing with a turbuler shaker mixer was used as a developer.

Using a photoconductor and cleaning device integrated unit that fixes the photoconductor to a part of the cleaning device with the developer,
The pressing force of the cleaning blade against the photoconductor is 35 g / cm
When the image was copied using an electrophotographic copying machine, the image density was 1.58 (hereinafter, the image density is a value measured with a Macbeth RD-918 reflection densitometer), and the characters and fine lines were clear. An image with good photo reproducibility was obtained. FIG. 4 is a side view of the used photoconductor / cleaning apparatus integrated unit, and FIG. 5 is a side view of the copying apparatus.

Further, when 10,000 copies were continuously made, a good image with no fog and no fog was obtained without poor cleaning, drum fusion and the like.

FIG. 6 shows the relationship between the number of continuous copies and scraping of the photoconductor (DPC) at this time.

Example 2 A developer was prepared in the same manner as in Example 1 except that 5 parts by weight of phthalocyanine blue was used as a coloring agent.

 Table 1 shows the physical property values of the developer.

When this developer was copied using an electrophotographic copying machine in which the pressing force of the cleaning blade used in Example 1 was 35 g / cm, the developer had an image density of 1.61, the solid portion was uniform, and the gradation was good. A cyan image was obtained.

In addition, there was a clear image with less toner scattering and fogging even by continuous copying.

Example 3 Developed using a toner obtained by mixing and dispersing 0.6 parts by weight of a silica fine powder treated with a fluidity improver dimethyldichlorosilane in a Henschel mixer for 2 minutes and 30 seconds, to the classified product prepared according to Example 1 according to the above formulation. An agent was prepared. Table 1 shows the physical property values of the developer.

When this developer was copied using an electrophotographic copying machine in which the pressing force of the cleaning blade used in Example 1 was 35 g / cm, a clear magenta image having an image density of 1.65 and being free from scattering and fog was obtained. Was done. Even when copying 10,000 sheets continuously, image deterioration such as toner scattering, scattering, fogging, etc. was small, and cleaning failure, filming, etc. did not occur.

Comparative Example 1 In Example 1, the pressure of the cleaning blade was set to 10
When copying was performed using an electrophotographic copying machine with g / cm, high density was initially exhibited and good images were obtained, but image stains occurred due to fusion of the toner on the photoreceptor after several tens of copies. .

Comparative Example 2 A developer was prepared using the toner in Example 1 in which the mixing time of the fluidity improver with the Henschel mixer was reduced to 1 minute.

 Table 1 shows the physical property values of the developer.

When this developer was copied using an electrophotographic copying machine in which the pressure of the cleaning blade used in Example 1 was 35 g / cm, an image density of 1.55 was obtained, and an image with good reproducibility of characters and pictures was obtained. Was done. However, with continuous copying of 1000 sheets, white streaks occurred in the circumferential direction of the photoreceptor in the image area, and a low-quality image with noticeable fog was observed in the non-image area.

When the photoreceptor after copying was observed with an optical microscope, a filming phenomenon was confirmed.

Comparative Example 3 In Example 1, the pressing force of the cleaning blade was 55
When an image was copied using an electrophotographic copying machine of g / cm, a good image was obtained in the initial stage, but the photoreceptor was abraded by continuous copying and the blade was worn.

 FIG. 6 shows a graph of the number of copies and the photoreceptor scraping.

[Effects of the Invention] The present invention provides a high resolution and high density by defining various characteristic values of the toner in addition to the pressing force of the cleaning blade against the photoreceptor. This is an image forming method that does not cause a defect or a filming phenomenon and has less scraping of the photoconductor.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the configuration of a known cleaning device, FIG. 2 shows a triboelectric charge amount measuring device, and FIG. 3 shows the relationship between the mixing time (minute) of the Henschel mixer and the fluidity index in Example 1. FIG. 4 is a side view of a photoconductor / cleaning device integrated unit, FIG. 5 is a side view of a copying apparatus used in the embodiment, and FIG. 6 is a photoconductor during continuous copying. It is a graph which shows shaving.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 9/08 G03G 9/113 G03G 21/00

Claims (1)

(57) [Claims] A developing step of developing an electrostatic latent image formed on the OPC photoreceptor with a two-component developer having a toner and a resin-coated ferrite carrier to form a toner image; a transferring step of transferring the toner image And an image forming method having a cleaning step of removing residual toner remaining on the OPC photoreceptor after the transfer step using a cleaning device having an elastic cleaning blade pressed against the OPC photoreceptor; Using an integrated unit of the photoconductor and the cleaning device to which the OPC photoconductor is fixed, the pressing force of the cleaning blade against the OPC photoconductor is 2
5 to 45 g / cm, wherein the toner comprises at least a colorant-containing resin particle and a fluidity improver, has a volume average particle size of 5 to 10 μm, a fluidity index of 5 to 25%, and has a resin-coated ferrite carrier. Wherein the triboelectric charge of the toner is from -15 to -35 [mu] C / g.