JPH06167825A - Electrophotographic process - Google Patents

Abstract

PURPOSE:To remarkably improve cleanability with a rubber blade even in the case of a spherical toner having high roundness. CONSTITUTION:In this electrophotographic process adopting cleaning with a rubber blade, a toner having 1.0-15.0 fC absolute value of the amt. of electric charges is used and this toner is combined with an electrophotographic sensitive body so that the average adhesive strength of toner particles to the sensitive body is regulated to the range of 5.0X10<-9>-1.0X10<-7> N, the number of toner particles having >=1.0n10<-9> N adhesive strength to <=1.0% and the number of toner particles having >=1.0X10<-7> N adhesive strength to <=1.0% when the adhesive strength is measured by a centrifugal separation method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in various electrophotographic methods for copying, faxing, printers and the like. More specifically, it is possible to effectively carry out cleaning work and to obtain a high quality copied image. The present invention relates to an electrophotographic method capable of obtaining

[0002]

2. Description of the Related Art In electrophotography, an electrostatic latent image is formed on the surface of a photoconductor, the electrostatic latent image is developed with toner, the formed toner image is transferred to paper, and the transferred toner is transferred. A system that fixes an image is generally adopted, but untransferred toner always remains on the surface of the photoconductor after toner transfer.
It is necessary to remove this residual toner by cleaning prior to repeating the process.

To clean the photoreceptor, a fur brush,
Although various methods such as a method using a magnetic brush and a method using a rubber blade are used, the method using a rubber blade is superior in terms of cost of a cleaning mechanism and easiness of operation.

Japanese Unexamined Patent Publication (Kokai) No. 1-99060 prevents the cleaning blade from reversing and the edge portion of the blade being torn off due to friction to cause chipping or development when natural color development is used. In order to do so, the cleaning means using a rubber blade and the glass transition point 60
Process speed 8 having a developing means using a dry non-magnetic toner having a binder resin at a temperature of ℃ or below and a resin-coated magnetic material
It is stipulated that an electrophotographic photosensitive member having an average surface roughness in the range of 0.3 to 5.0 is used in an electrophotographic process of 0 mm / sec or more.

[0005]

In the above prior art, the resin glass transition point (Tg) of the toner is limited to 60 ° C. or lower and the process speed is limited to 80 mm / sec. This is because when the blade cleaning is performed at a high speed, the cleaning blade is likely to be turned over or the edge of the blade is broken.

In recent years, instead of the irregular toner by the pulverizing and classifying method, a spherical toner by the suspension polymerization method or the dispersion polymerization method,
Spherical toner produced by hot air flow and fluidized granulation has excellent fluidity,
Although it is attracting attention as a toner excellent in developing workability,
A problem that must be solved when spherical toner is used is poor cleaning performance of the toner remaining on the surface of the photoconductor.

That is, spherical toner, particularly spherical toner having a high roundness, has a poor blade cleaning property as compared with the irregular toner, and has a glass transition point of 60 as a resin constituting the toner.
Even if the temperature is higher than 0 ° C. or if the process speed is lower than 80 mm / sec, the adhesive force to the photoconductor is large and a problem such as poor cleaning occurs.

In order to solve this problem, in a system using spherical toner, a brush is attached in the cleaning process or the linear pressure of the cleaning blade is increased, but in the former case, the cost of the copying machine is increased. In the latter case, there is a problem in that the photoconductor is damaged and the blade is inverted.

Further, Japanese Patent Laid-Open No. 4-110861 discloses that
Appropriate amount of charge area distribution area is 70% of total charge quantity distribution area
A method for performing an electrophotographic process using the above electrostatic image developer is disclosed, and Japanese Patent Application Laid-Open No. 4-86747 discloses a charge amount per toner surface area of -20 to 1.5.
It is in the range of fC / m ² and the charge amount is 0.5Q to 2Q.
There is disclosed an electrophotographic toner in which particles within the range of (Q: average amount of charge) account for 70% or more of the total in number average. These techniques are extremely significant because they attempt to improve the image quality by controlling the force acting on the toner particles during the electrophotographic process by defining the charge amount distribution of the toner.

However, in the actual electrophotographic process, the forces acting between the toner and the photoconductor drum, between the toner and the paper surface, and between the toner are van der Waal in addition to the electrostatic force.
Since the forces such as the s force and the liquid bridging force due to water are intricately entangled with each other, even if the charge amount distribution of the toner is simply adjusted within a certain range, a good image is not always obtained. For example, when a spherical toner having a high roundness is used, the above-mentioned problem has not been solved yet.

Therefore, an object of the present invention is to provide an electrophotographic method in which blade cleaning is effectively performed even when a spherical toner having a high roundness is used and a good image can be stably obtained. Especially.

[0012]

According to the present invention, in an electrophotographic method using cleaning with a rubber blade, the absolute value of the charge amount as toner is 1.0 to 15.0f.
In addition to using the toner of C, as an electrophotographic photosensitive member and a toner, the average adhesive force was measured in a range of 5.0 × 10 ^{−9 to} 1.0 × 10 ⁻⁷ N as measured by a centrifugal force. Yes, and the adhesive force is less than 1.0 × 10 ^-9 N and the toner number% is 1.0 or less, and the adhesive force is greater than 1.0 × 10 ^-7 N and the toner percentage% is 1.0 or less. An electrophotographic method is provided which is characterized by using a combination of

In the present invention, it is preferable to perform cleaning with the linear pressure of the rubber blade on the photosensitive member being in the range of 2.0 to 30 g / cm. Toner used is 3-25 μ
It is desirable that the toner has a particle size distribution in the range of m, especially 5 to 18 μm, and further, it is preferable that the toner has a volume-based median diameter of 5 to 20 μm. The composition of the toner to be used is not particularly limited. However, a non-magnetic toner is preferable.

[0014]

The present invention provides an electrophotographic photosensitive member having an average adhesive force (fad) within a certain range as measured by a centrifugal separation method, regardless of whether the toner particles used are spherical or amorphous. It is based on the finding that the cleaning property by the rubber blade can be remarkably improved by using the combination with the toner.

As already pointed out, the spherical toner, particularly the spherical toner having a high roundness, has a drawback that the blade cleaning property is poor as compared with the irregular toner. This seems to be closely related to the fact that the spherical toner has a larger contact area with the surface of the photoconductor as compared with the irregular toner.

According to the present inventors, the ease of cleaning with a rubber blade is closely related to the average adhesive force (fad) obtained by measuring the particle adhesive force by the centrifugal separation method, and this average adhesive force is 5. 0 × 10 ^{-9 to} 1.0 × 10 ^-7 N (Newton), particularly preferably 1.0 × 10 ^{-8 to} 6.0 × 10 ^-8
In the range of N and the adhesive force is less than 1.0 × 10 ⁻⁹ N, the number% of the toner is 1.0 or less and the adhesive force is 1.0 × 10.
^In the combination of the electrophotographic photosensitive member and the toner in which the number% of toners larger than ⁻⁷ N is 1.0 or less, cleaning failure can be effectively eliminated, and a good image can be stably obtained. I found it.

That is, according to the present invention, the problem of defective cleaning when spherical toner is used can be solved, and good cleaning can be performed with a rubber blade without using a cleaning brush. Further, the linear pressure used for cleaning can be set to a relatively small range of 2.0 to 30 g / cm, and abrasion of the photoconductor and the rubber blade can be prevented, and excellent cleaning workability can be obtained.

In the present specification, the average adhesive force (fad) obtained by measuring the particle adhesive force by the centrifugal separation method means the following formula (1): fad = (π / 6) ² · ρ · Di ³ · r · (2nπ / 60) ² (1) In the formula, Di is the toner particle size (m), ρ is the toner density (kg / m ³ ), r is the radius of gyration (m),
It is defined as the number of rotations (rpm) when the separation rate by centrifugal force is 50%.

The principle of measuring the particle adhesion force by the centrifugal separation method according to the present invention is as follows. Mass mi of the particles (the spherical) [particle size: Di, Density: [rho] separation force from the plane of the fi the following formula (2): fi = mi · α = mi · r · ω 2 = (π / 6 ) ² · ρ · Di · r · ω ² (2) where α is acceleration, r is radius of gyration, and ω is angular velocity.

When the centrifugal force when the separation rate of particles due to the centrifugal force is 50% is the average adhesive force (fad), the separating force = adhesive force. Therefore, the following formula (3): fad = mi・ R ・ ω ² = (π / 6) ²・ ρ ・ Di ³・ r ・ ω ² (3), where ω = (2nπ /
60), the above formula (1) is derived, and the adhesive force is obtained by obtaining the number of rotations at the time when the particles are separated.

Details of the apparatus used for the measurement and details of the measuring method are described in the examples described later.

When the particle size of the toner particles is changed and the particle residual ratio with respect to the number of revolutions for each particle size is obtained, the curve shown in FIG. 1 is obtained. FIG. 1 is a plot of the relationship between the rotation speed on the horizontal axis and the residual ratio on the vertical axis. The particle ratio decreases with increasing rotation speed at the same particle size, but at the same rotating speed, the particle ratio decreases. It shows that the larger the diameter, the smaller the residual rate.

From FIG. 1, the rotational speed n at the residual toner rate of 50% is determined, and the average adhesive force (fad) is determined from the rotational speed n by the equation (1). FIG. 2 is a plot of the relationship between the particle diameter on the horizontal axis and the average adhesive force (fad) on the vertical axis.

According to a number of experiments conducted by the inventor of the present invention, there is a fairly good correspondence between the average adhesive force (fad) measured as described above and the cleaning failure during actual rubber blade cleaning, and the average adhesive force (fad) is 7 If it is higher than 0.0 × 10 ⁻⁶ N, cleaning failure will occur, but if the toner and electrophotographic photosensitive member are combined below this value, cleaning failure can be eliminated. Also 1.0 x 1
When it is lower than 0 ^-8 , the toner is not effectively held on the photoconductor, and problems such as poor development and toner scattering tend to occur. Further, the number% of toner ^particles having an adhesive force smaller than 1.0 × 10 ^-9 N is 1.0 or less, and the adhesive force is 1.0 × 10 ^-7 N.
It is also important that the number% of the larger toner is 1.0 or less, and even if the average adhesive force (fad) is within the range described above, if the distribution is broad, the adhesive force is The number of toners outside the range specified in the present invention increases, and the object of the present invention cannot be achieved. Such adjustment of the adhesive force between the photosensitive member and the toner is performed by adjusting the surface average roughness (Rz) roughness of the photosensitive member, and the adjustment of the adhesive force distribution in the toner is performed based on FIG. This is done by adjusting the particle size distribution of the toner.

In FIG. 3 for explaining the contact state between the toner and the surface of the electrophotographic photosensitive member, the combination of the spherical toner T having a high sphericity and the smooth surface P of the electrophotographic photosensitive member shown in FIG. Compared to the combination of the irregular toner Ta and the smooth surface P of the electrophotographic photosensitive member shown in B), the contact area between the two is large, which is the reason why the average adhesive force (fad) increases. On the other hand, as shown in (C), when the surface of the electrophotographic photosensitive member is the roughened surface Pb,
Even in the case of the spherical toner T, the contact area between them is reduced, the average adhesion force (fad) can be controlled within the range defined by the present invention, and the cleaning failure can be eliminated. However, when the surface of the electrophotographic photosensitive member is the surface Pc which is too rough as shown in (D), the toner particles T enter the groove G and the contact area increases,
The average adhesive force (fad) exceeds the range specified in the present invention, and cleaning failure occurs.

Therefore, in the present invention, when an electrophotographic photosensitive member having a surface average roughness (Rz) in the range of 0.1 to 2 μm is used, the average adhesive force (fad) falls within the range specified in the present invention. It is easy to control, and when cleaning is performed with the angle formed by the roughness forming groove formed on the surface of the photoconductor and the running direction of the rubber blade being in the range of 10 to 80 degrees, spherical toner Cleaning workability is improved.

According to the present invention, by using a combination of the toner and the electrophotographic photosensitive member having an average adhesive force of 5.0 × 10 ^{−9 to} 1.0 × 10 ⁻⁷ N, a spherical toner can be obtained. Can also be used with a uniform particle size, and even if it does not contain a fine particle size (particle size of 5 μm or less), it does not adversely affect the cleaning performance, and toner scattering and fogging due to the inclusion of fine particle toner It can be prevented.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 4 showing the apparatus used in the electrophotographic method of the present invention, a photosensitive layer (photoconductive layer) 2 is provided on the surface of a metal drum 1 which is driven and rotated. The photoconductor layer 2 is made of, for example, an inorganic photoconductor such as Se, ZnO, CdS, or amorphous silicon, or a function-separated type or other type organic photoconductor.

Around the drum, a main charging corona charger 3; an image exposure mechanism composed of a document exposure lamp 4, a document supporting transparent plate 5 and an optical system 6; a developing mechanism 8 having a developer 7; A corona charger 9; a paper separating corona charger 10; a charge eliminating lamp 11; and a blade cleaning mechanism 12 are provided in this order.

Image formation by this electrophotographic method is performed as follows. First, the photoconductor layer 2 is charged by the corona charger 3 with electric charges of constant polarity. Next, the lamp 4 illuminates the original 13 to be copied, and the photoconductor layer 2 is exposed to the light beam image of the original through the optical system 6 to form an electrostatic latent image corresponding to the original image. This electrostatic latent image is visualized by the developing mechanism 8 to form a toner image. The transfer paper 14 is supplied so as to come into contact with the drum surface at the position of the toner transfer charger 9, and a corona charger having the same polarity as the electrostatic image is performed from the back surface of the transfer paper 14 to transfer the toner image to the transfer paper 14. Let The transfer paper 14 on which the toner image is transferred is electrostatically separated from the drum by the charge removal of the separation corona charger 10 and sent to a processing area such as a fixing area (not shown).

After the toner transfer, the photoconductor layer 2 is entirely exposed by the static elimination lamp 11 to erase the residual charges, and then the blade cleaning mechanism 12 removes the residual toner from the photoconductor layer 2.

The toner used in the present invention has an absolute value of electric charge of 1.0 to 15.0 fC, and particularly 3.0 to 10.0 f.
It must be in the C range. That is, when the charge amount is smaller than 1.0 fC, the electrostatic attraction acting on the toner is not sufficient even if the adhesive force with the surface of the photoconductor is set within the range described above. It becomes difficult to attach itself to the surface of the photoconductor. See also 15.
If it is larger than 0 fC, the electrostatic attraction acting on the toner is too large, and image fog or the like occurs. The adjustment of the charge amount is performed by adjusting the triboelectric charging condition of the toner and the toner blending component described later.

In the present invention, spherical or quasi-spherical toner is used as the toner. Although these spherical toners are excellent in fluidity, developing workability, and electrical characteristics, they are disadvantageous in that they are inferior in cleaning. However, in the present invention, since the cleaning property is improved, the advantages of the spherical toner are You can make use of it. As long as the particle shape is within the above range, this toner may be an amorphous one produced by the melt-kneading / pulverization method and spheroidized in a hot air flow, or a spherical one produced by the dispersion or suspension polymerization method. However, the latter one is preferable because it is easy to manufacture. Further, it is particularly preferable to use a toner having a high sphericity, for example, a toner having a roundness of 0.85 or more. In the present specification, circularity means the following formula (4): circularity = 4πA / (PRM) ² (4) In the formula, A is obtained by measuring a transmission image of particles with an image analyzer. The particle area is defined as PRM, and PRM is the particle perimeter obtained in the above measurement.

The toner used in the present invention is a toner having a composition known per se, which has a sensible property, a coloring property and a fixing property, and a colorant and a charge control agent in the fixing resin medium or a toner known per se. It contains a compounding agent.

First, as the fixing resin medium, either a thermoplastic resin or a thermosetting resin in the form of an uncured or precondensate is used. For example, a vinyl aromatic resin such as polystyrene, an acrylic resin, a polyvinyl acetal resin. , Polyester resin, epoxy resin, phenol resin, petroleum resin, polyolefin resin, and the like. Among these, styrene resin, acrylic resin, or styrene-acrylic copolymer resin is preferably used.

As the coloring agent to be contained in the resin, for example, the following inorganic or organic pigments and dyes may be used alone or in combination of two or more kinds, but of course the present invention is not limited thereto. Carbon black such as furnace black and channel black; iron black such as ferric tetroxide; titanium dioxide such as rutile type or anatase type; phthalocyanine blue; phthalocyanine green; cadmium yellow; molybdenum orange; pyrazolone red; fast violet B etc.

As the charge control agent, any charge control agent known per se, for example, an oil-soluble dye such as nigrosine base (CI50415), oil black (CI20150), spirone black, or the 1: 1 type or 2: Type 1 metal complex salt dye, naphthenic acid metal salt, fatty acid, soap, resin acid soap and the like are used.

The toner used in the present invention has 90% by number or more of particles having a particle diameter in the range of 3 to 25 μm so that the distribution of the adhesive force between the toner and the photosensitive member is in the above range. It should have a particle size distribution. That is, if the particle size distribution is out of the above range, it becomes difficult to adjust the adhesive force distribution within the range defined in the present invention, and for example, when the particle size distribution deviates to a side smaller than the above range, The cleaning property tends to decrease, and when the particle size distribution is biased to a side larger than the above range, the resolution tends to decrease. Further, it is preferable that the number of particles having a particle diameter of less than 5 μm has a particle size distribution of 3% by weight or less of the entire particles, which can prevent toner scattering and fogging due to fine particle toner.

The preferred toner of the present invention is obtained by subjecting a toner-forming composition containing at least a radical polymerization initiator, a vinyl-based monomer and a colorant to suspension polymerization in an aqueous medium, and directly using this suspension system. Obtained by forming toner particles. The resulting toner particles contain components necessary for the toner such as a coloring agent in addition to the vinyl polymer fixing agent, and the particles are spherical and have a median diameter of 3 to 25 suitable for the toner.
.mu.m, especially in the range of 5 to 20 .mu.m, and the degree of dispersion of the particle size represented by D25 / D75 is 1.7 or less, especially
A particle size of 1.5 or less is monodisperse or similar.

The above toner can be used alone as a one-component magnetic toner containing a magnetic substance such as ferric tetroxide, but in the present invention, a non-magnetic toner is used and combined with a magnetic carrier. It is preferable to use it as a two-component developer.

In the present invention, as the magnetic carrier, ferrosoferric oxide, ferrite, iron powder and the like known per se are used. In particular, a ferrite-based magnetic carrier is suitable.
The carrier used may be an uncoated carrier, or
It may be a resin-coated carrier coated with a resin known per se, for example, a silicone resin, an acrylic resin, an epoxy resin, a fluororesin or the like.

The carrier used in the present invention has an average particle size of 30 to 200 μm, preferably 50 to 150 μm.
It is preferable to use those having a particle size of 50 μm or less and having a particle size distribution of 1% by weight or less of the total. The density of the magnetic carrier depends on the carrier concentration C / D,
Generally, it is preferable that the density ρc is 2.0 to 8.0 g / cm ³ , and the saturation magnetization of the carrier is preferably 30 to 70 emu / g. The magnetic carrier is preferably a ferrite carrier that satisfies the above conditions, particularly a spherical ferrite carrier. The particle size distribution satisfies the above-mentioned conditions, but preferably has a normal distribution or a distribution close to this.

The toner weight fraction T / D in the developer is generally
It is preferably in the range of 2.0 to 10%, particularly 3.0 to 6.0%. The electric resistance of the developer as a whole is 1 × 1.
It is preferably in the range of 0 ^{−7 to} 1 × 10 ¹¹ Ω · cm.

As the photoconductor, the average adhesion force (fad) was 1.0 × 10 ^{−8 to} 7.0 × 10 ⁻⁶ , especially in combination with the spherical toner used in the measurement of the particle adhesion force by the centrifugal separation method.
Any electrophotographic photosensitive member can be used as long as it is a photosensitive member having a ^{density of} 5.0 × 10 ^{−8 to} 5.0 × 10 ⁻⁷ N. ,
For example, a selenium photoconductor, an amorphous silicon photoconductor, a zinc oxide photoconductor, a cadmium selenide photoconductor, a cadmium sulfide photoconductor, various function-separated laminated type or single-layer type organic photoconductors are all used.

The organic photoreceptor is a single dispersion layer type in which an organic photosensitive layer is provided on a conductive substrate, and the organic photosensitive layer is composed of a charge generating agent and a charge transporting agent dispersed in a resin medium. Alternatively, a laminated organic photoreceptor having a charge generation layer and a charge transport layer provided in this order on a conductive substrate is used.

Examples of the charge generating agent include selenium, selenium-tellurium, amorphous silicon, pyrylium salt,
Azo pigments, disazo pigments, Ansanthuron pigments,
Phthalocyanine pigments, indico pigments, slene pigments, toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments and the like are used alone or in combination of two or more.

Of the charge transfer agents, any hole transfer material may be used as the hole transfer agent. Examples thereof include oxadiazole compounds, styryl compounds, carbazole compounds, organic polysilane compounds, pyrazoline compounds, hydrazone compounds, Nitrogen-containing compounds such as triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiazoazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, etc. A compound or the like is used. On the other hand, as the electron transfer agent, a diphenoquinone derivative, a quinone derivative or the like is used.

Various resins can be used as the resin medium in which the above-mentioned respective agents are dispersed. For example, a styrene polymer, an acrylic polymer, a styrene-acrylic polymer, an ethylene-vinyl acetate copolymer. ,polypropylene,
Olefin-based polymers such as ionomer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester,
Alkyd resin, polyamide, polyurethane, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin,
Examples include various polymers such as a phenol resin and a photocurable resin such as epoxy acrylate. These binder resins may be used alone or in combination of two or more.

In this type of organic photoreceptor, the charge generating agent is 2.0 to 5.0% by weight, and particularly 3.0 to 4.0, by weight based on the solid content.
It is preferable that it is contained in the photosensitive layer in an amount of 30% by weight, and the charge transfer agent is contained in an amount of 30 to 80% by weight, particularly 40% by weight, based on the solid content.
It is preferable that the content is from 60 to 60% by weight in the photosensitive layer.

In the present invention, an electrophotographic photosensitive member having an average surface roughness (Rz) in the range of 0.1 to 2 μm is used in order to bring the average adhesive force (fad) into the range specified in the present invention. Preferably. In the present specification, the surface average roughness (Rz) is defined in JIS B0601. According to this standard, roughness includes maximum height roughness, ten-point average roughness, and center line average roughness, but the roughness in this specification is defined by ten-point average roughness. Say

In order to form this rough surface on the surface of the electrophotographic photosensitive layer, any method known per se, for example, a method using an abrasive, a mechanical polishing method such as sand blasting method, or drying of the organic photosensitive layer can be used. A method of adjusting the conditions to roughen the surface, a method of transferring a previously formed rough surface to the photosensitive layer surface, a rough surface is previously formed on the conductive substrate surface, and this rough surface is used as the photosensitive layer surface. The method of revealing can be appropriately used depending on the thickness and type of the photosensitive layer. Among these, the method by mechanical polishing is preferable in terms of accuracy and reproducibility.

When forming a rough surface on the surface of the photoreceptor,
When the angle formed by the roughness forming groove formed on the surface of the photoconductor and the running direction of the rubber blade is in the range of 10 to 80 degrees, satisfactory results can be obtained in terms of cleaning property.

In the present invention, as the rubber blade used for cleaning, urethane rubber, silicone rubber,
Various rubbers such as fluororesin rubber, NBR, and SBR are used, and the blade having a thickness of 1 to 3 mm is used.

Cleaning with a rubber blade can be carried out by a means known per se, but as described in Japanese Patent Laid-Open No. 60-25684 proposed by the present applicant, a holder for supporting the root of the blade is used. , Using a fulcrum that supports the holder so that it can swing and a pressing mechanism that presses the blade tip against the surface of the photoconductor, the fulcrum and the blade contact the tip of the blade and the photoconductor on the delivery side of the photoconductor. It is arranged so that the angle (β) formed by the line connecting the tip and the fulcrum with respect to the photoconductor is larger than the angle (α), and the blade tip is moved as the stress applied increases as the applied stress increases. It is preferable to perform cleaning by arranging the blades in an elastic engagement relationship such that the blades are retracted and the deflection of the blade is increased. It is preferable that the angle α is generally 10 to 35 degrees and the angle β is generally 25 to 45 degrees.

The linear pressure of the rubber blade on the photosensitive member is not particularly limited, but in the present invention, this linear pressure is 2.0 to 30 g.
Cleaning can be performed in a relatively small range of / cm.

[0056]

The present invention will be described in more detail by the following examples.

(1) Measurement of Adhesive Force The following device was used for measuring the adhesive force. Centrifuge rotor: Hitachi Koki angle rotor RR
24A Centrifuge adapter: A jig for fixing a glass plate made by Hitachi Koki (custom-made product) to the rotor Centrifuge: CR20B2 made by Hitachi Koki Maximum rotation speed 20000 rpm Maximum acceleration 40700G (r = 91mm) Image analysis device: Avionics The arrangement of the EXCEL-II rotor was performed as shown in FIG. That is, the glass plate 21 is installed in the rotor 20 and the particle adhering surface 22
The outer surface of the rotary shaft 23 and the particle adhering surface 22.
The particles were arranged so that the distance r between and was 91 mm, the number of revolutions was changed, and the particle adhesion force was calculated from the equation (1).

(Preparation of Toner) The toner used in the following examples and comparative examples was prepared as follows. To a continuous phase prepared by adding 100 parts by weight of polyvinyl alcohol ("Gohsenol GH-17" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) as a suspension stabilizer to 400 parts by weight of water, the mixture having the composition shown in Table 1 below was added, and a homomixer was used. Granulation was carried out using the above, and a polymerization reaction was carried out at 80 ° C. for 8 hours under gentle stirring.

[Table 1]

(Preparation of Developer) Toner obtained above 3.
5 parts by weight was mixed and stirred with 100 parts by weight of a magnetic ferrite powder carrier coated with an acrylic polymer to prepare a two-component developer.

Examples 1 and 2 and Comparative Examples 1 and 2 A printing durability test was conducted using the above-mentioned developers. As the test machine, a copying machine DC-4055 manufactured by Sanda Kogyo Co., Ltd. was used. The results are shown in Table 2.

[Table 2]

[0061]

According to the present invention, even with spherical toner having a circularity of 0.85 or more, the average adhesive force (fad) measured by the particle adhesive force by the centrifugal separation method falls within a certain range. By using a combination of a certain electrophotographic photosensitive member and toner, the cleaning property by the rubber blade can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a graph in which the particle residual ratio with respect to the rotation speed for each particle diameter is obtained by changing the particle diameter of toner particles, and the relationship between the two is plotted with the rotation speed as the horizontal axis and the residual ratio as the vertical axis.

FIG. 2 is a graph plotting the relationship between the particle diameter on the horizontal axis and the average adhesive force (fad) on the vertical axis.

FIG. 3 is an explanatory diagram for explaining a contact state between the toner and the surface of the electrophotographic photosensitive member, wherein (A) has a circularity of 0.8.
A combination of 5 or more spherical toners and a smooth surface of an electrophotographic photosensitive member, (B) a combination of irregular toner and a smooth surface of an electrophotographic photosensitive member, and (C) a roughened photosensitive member surface and spherical shape. Combination with toner, (D) shows the combination of toner particles with a too rough surface.

FIG. 4 is a schematic layout diagram showing an apparatus used in the electrophotography of the present invention.

FIG. 5 shows an apparatus for measuring the adhesive force between the toner and the photoconductor according to the present invention.

Claims (4)

[Claims] 1. An electrophotographic method using cleaning with a rubber blade, wherein a toner having an absolute value of electric charge of 1.0 to 15.0 fC is used as the toner, and a centrifugal separation method is used as the electrophotographic photosensitive member and the toner. The average adhesive force is 5.0 × 10 ^{-9 to} 1.0 ×
In the range of 10 ⁻⁷ N and the adhesive force is less than 1.0 × 10 ⁻⁹ N, the number% of toner is 1.0 or less and the adhesive force is 1.0.
An electrophotographic method, characterized in that a combination is used in which the number% of toner particles larger than × 10 ⁻⁷ N is 1.0 or less. 2. The electrophotographic method according to claim 1, wherein the toner has a particle size distribution within a range of 3 to 25 μm. 3. The electrophotographic method according to claim 1, wherein the toner has a volume-based median diameter of 5 to 20 μm. 4. The linear pressure of the rubber blade on the photosensitive member is 2.
The electrophotographic method according to claim 1, wherein cleaning is performed in a range of 0 to 30 g / cm.