JP2006195079A - Two component development method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two component development method where the flying of a toner with high efficiency is realized, and the stable formation of an image with a high definition picture free from the generation of image defects is made possible. <P>SOLUTION: In the method of performing development using a two component developer for electrophotography composed of a toner and a magnetic carrier, the average charging amount of the toner Q/M[μC/g] is 40 to 60[μC/g], and the average adhesion force of the toner to the magnetic carrier lies in the range of 15 to 30[nN] in a measurement method using a centrifugal separation process. Alternatively, the distance between a development sleeve and an image carrier such as a photosensitive drum lies in the range of 100 to 700[μm], and voltage in which an alternating field is superimposed on a DC bias component is applied between the development sleeve and the image carrier such as a photosensitive drum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a two-component developer used in an electrophotographic image forming apparatus used in a copying machine, a laser beam printer, or the like.

  Conventionally, a number of methods are known as electrophotographic methods. In general, a photoconductive substance is used to form an electric latent image on a photosensitive member (image carrier) by various means, and then the electrophotographic method is performed. The latent image is developed with toner to form a visible image. If necessary, the toner image is transferred to a transfer material such as paper, and then the toner image is fixed on the transfer material by heat and pressure to obtain a copy. Is. In addition, toner particles that are not transferred onto the transfer material but remain on the photoconductor are removed from the photoconductor by a cleaning process.

  In the process of developing the electrostatic latent image, toner particles charged to a polarity opposite to that of the latent image are attracted by an electrostatic force and adhered onto the electrostatic latent image. The developing method using toner is roughly divided into a method using a so-called two-component developer in which a small amount of toner is dispersed in a medium called a carrier (solid carrier), and a so-called using toner alone without using a carrier. And a method using a one-component developer.

  The two-component developer is a mixture of toner and carrier, and the toner adheres to the carrier surface due to charging due to contact between the two. When such a two-component developer is transported to the electrostatic latent image, the toner is electrostatically attracted to the electrostatic latent image portion, and thus is separated from the carrier surface.

  However, if the toner and the carrier are excessively charged and the adhesion between the toner and the carrier becomes too strong, the toner will be difficult to separate from the carrier. A phenomenon such as a decrease in image density occurs. For such inconvenience, a technique is adopted in which a bias electric field is applied between the developer and the latent image and only the toner is easily conveyed to the latent image with the help of this electric field. In order to perform control by applying the bias electric field, the developer must have a certain degree of conductivity.

  However, chargeability and conductivity are contradictory properties. If the conductivity is more than necessary, sufficient chargeability cannot be obtained, resulting in insufficient charging and inconvenience such as toner flying. .

  From such a background, generally, as a carrier constituting such a two-component developer, a conductive carrier and an insulating carrier coated with a resin or the like are used.

  Oxidized or unoxidized iron powder is usually used as the conductive carrier. However, the developer containing this iron powder carrier as a component has unstable triboelectric chargeability with respect to the toner and is formed by the developer. There is a drawback that fogging occurs in the visible image. This is because heat is generated between the carrier particles and the toner particles during contact with the developer, and contact between these particles and a stirring member such as a screw, collision, etc., and some of the toner particles physically adhere to the surface of the carrier particles. The film is formed, that is, the spent state is affected.

  This spending increases the electrical resistance of the carrier particles and lowers the bias current. Also, the formation of a toner film on the surface of the carrier particles is remarkably accumulated, and the frictional charging between the carrier particles and the toner particles. As a result, the triboelectric charging characteristics of the entire developer deteriorate. Due to these factors, the image density of the resulting visible image decreases, fog increases, and copy quality decreases. Therefore, if electrostatic latent image development is continuously performed using a developer containing an iron powder carrier, the developer deteriorates after a small number of copies and needs to be replaced early, resulting in an increase in cost. It leads to.

  Therefore, in order to compensate for the above problems, an insulating coating carrier in which the carrier surface is coated with a resin has been studied. In general, the coating carrier is typically one in which the surface of magnetic particles (core material) made of iron, magnetite, nickel, ferrite or the like is coated with a resin coating layer. The developer containing the coating carrier as a component has an advantage of excellent durability and long service life. However, since the apparent resistance of the coating carrier is as high as about 1 × 10 14 Ωcm, for example, a high triboelectric charge amount is given to the toner, and the carrier tends to adhere to the image portion during development. In addition, peripheral effects tend to occur, and there are drawbacks such as poor reproducibility of wide black areas and halftone areas, which is a practical problem.

  Among the problems in the development process, the important problems related to the flying of the toner are the charge amount and the adhesion between the carrier and the toner. When the magnitude of the Coulomb force generated by the developing electric field exceeds the adhesion force, the toner flies to the photoconductor. The Coulomb force and the adhesion force depend on the charge amount of the toner.

  Therefore, if the friction between the coating carrier and the toner, which has been developed to compensate for the problems in the developing portion, is successfully performed and an appropriate charge amount is given, the toner can be placed on the latent image portion. In particular, in recent years, as toners are designed for higher image quality, problems that cannot be dealt with only by the charge amount of the toner have appeared.

  Toner design is important for such problems, and control of toner adhesion is also an important issue. In particular, the adhesion force is very related to the flying of the toner in the developing portion and the high transferability in the transferring portion.

  In particular, the adhesion force related to the toner flying in the developing part is divided into electrostatic force resulting from toner charging and other van der Waals force / liquid cross-linking force. Since the charge amount is lowered, it becomes difficult to control by the developing electric field. When this happens, it is necessary to further increase the charge amount in the toner flight. However, since the adhesive force sufficiently depends on the charge amount, high image quality cannot be expected unless the adhesive force is comprehensively controlled.

  Conventional reports on toner adhesion include the definition of toner for improving cleaning properties (see, for example, Patent Document 1). Furthermore, there is a method using a centrifugal separation method for measuring the adhesion force to the photoconductor (see, for example, Patent Document 2). These correspond to problems in the transfer portion and the cleaning portion by measuring the toner adhesion force by the centrifugal method. On the other hand, there is one that measures the adhesion force to the carrier in the developing portion (see, for example, Non-Patent Document 1). However, in the above reported example, there is a concern that the toner is attracted to the adhesive side in order to make the developer adhere to the adhesive after the developer is created in the measurement of the electrostatic adhesion force, and the normal covering state cannot be formed. .

  Also, the particle size of the carrier is 100 μm, which is slightly larger than that of the carrier having a small particle size like the toner, and if the sample is prepared as in the reported example, the toner is separated from the carrier in the carrier having a small particle size. Will occur. In addition, there is a technique in which the adhesion force between the carrier and the toner is measured by using an impact method, not the centrifugal method (see Patent Document 3). Unlike other patent documents, this method pays attention to the distribution of toner adhesion consisting of electrostatic adhesion and non-electrostatic adhesion. A two-component developer having an adhesion distribution is disclosed.

Yutaka Fukuchi, et al. "Factors involved in toner adhesion" JapanHardCopy 97, Proceedings of the Electrophotographic Society, July 9, 1997, p.81-84 Japanese Patent No. 3253379 JP 2001-318485 A JP 2003-241416 A

  However, the technology disclosed so far as described above uses only the method of controlling the non-electrostatic adhesive force using the centrifugal method, and does not consider the electrostatic adhesive force. On the other hand, the impact method technology describes the overall adhesion force of the two-component developer, but there is no description of the relationship between the charge amount and the adhesion force, and the charge amount and the adhesion force are combined for image formation. You have to control it.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a two-component developing method that realizes efficient toner flying and enables stable and high-quality image formation without image defects.

In order to achieve the above object, the invention described in claim 1 is a two-component developer for electrophotography comprising a toner and a magnetic carrier, wherein the development is performed using the two-component developer.
The toner average charge amount Q / M [μC / g] of the toner is 40 [μC / g] to 60 [μC / g], and the average adhesion force of the toner to the magnetic carrier is determined by a centrifugal separation method. In the conventional measurement method, it is in the range of 15 [nN] to 30 [nN].

  According to a second aspect of the present invention, in the first aspect of the invention, the distance between the developing sleeve and an image carrier such as a photosensitive drum is in the range of 100 [μm] to 700 [μm], and the developing sleeve and the An alternating electric field is superimposed on a DC bias component between an image carrier such as a photosensitive drum.

  According to a third aspect of the present invention, in the first aspect of the present invention, the magnetic carrier of the two-component developer has an average volume particle size of 50 μm or less.

  The invention according to claim 4 is the invention according to claim 1, wherein the magnetic carrier is obtained by coating the surface of magnetic particles (core material) made of iron, magnetite, nickel, ferrite or the like with a resin coating layer. It is characterized by that.

  The invention described in claim 5 is characterized in that, in the invention described in claim 1, the adhesive force is measured using a centrifugal separation method.

  According to a sixth aspect of the invention, in the first aspect of the invention, in the centrifugal separation method, the perpendicular of the sample surface of the sample substrate on which one kind of adherend particles are uniformly fixed is perpendicular to the rotation axis. A centrifuge having a rotor that can be installed as described above, and a powder comprising at least one kind of fine particles having a centrifugal force generated by the rotation of the centrifuge and the adherend material particles on the sample substrate When fixing the adherend particles on the sample substrate in a powder adhesive force measuring method and apparatus characterized by measuring the adhesion force between the adhesive layers, the thickness of the adhesive layer is thinner than the adherent particle diameter. It is formed by means for uniformly applying to a layer, and a sample is used in which the adherent particles are embedded in a single layer in the adhesive layer and the powder composed of the fine particles is adhered to the exposed portions of the adherent particles. Adhesive strength of powder Characterized in that it is made by the measuring method and apparatus.

  According to the present invention, by controlling the developer charge amount and adhesion within an appropriate range, efficient toner flight can be realized, and stable high-quality image formation without image defects can be achieved. It can be.

  Embodiments of the present invention will be described below. First, the method for measuring the adhesion force by the centrifugal method in the two-component developer of the present invention will be described in detail.

  FIG. 1 is a schematic view of an adhesive force measurement sample according to the present invention.

  The adhesive 2 is uniformly applied to the sample substrate 1 and the carrier 3 is fixed more uniformly, and the electrophotographic nonmagnetic toner 4 is coated thereon. FIG. 2 is a diagram showing all steps of the adhesion force measurement. In the adhesive application step 5, the adhesive 2 is uniformly applied to the sample substrate 1 using a spin coater.

The spin coater 12 shown in FIG. 3 includes a motor 14 that rotates a pedestal 13, a power supply device 15, and a cover 16 that prevents the adhesive from scattering. Adhesive 2 was an epoxy resin adhesive, and “Cemedine High Super 5” was used in this example. The tensile shear bond strength of the adhesive used is 20 (N / mm ² ) or more when the maximum rotational speed of the centrifugal separator used is 100,000 (rpm). If the adhesive strength is not sufficient at 20 (N / mm ² ) or less, it is not preferable because the entire adhesion surface is separated from the sample substrate during centrifugation. The tensile shear bond strength of the adhesive of the present embodiment was 24.0 (N / mm ² ).

  The sample substrate 1 is fixed to the pedestal 13 of the spin coater 12, and the adhesive 2 is dropped while rotating at high speed to produce a uniform and thin layer. If the thickness of the adhesive is not smaller than the carrier particle size, it is buried in the adhesive layer and cannot be measured. Therefore, sufficient attention must be paid to the rotation time, adhesive viscosity, and adhesive curing time.

  In this embodiment, the viscosity of the main agent is 150 (Pa · S / 20 ° C.) and the curing agent is 75 (Pa · S / 20 ° C.). When rotated at about 10000 rpm, 45 μm, 60 in 30 seconds. The film thickness was 20 to 25 μm per second, and the film pressure was hardly changed even when a longer time was taken. If the curing time is too early, curing begins while spin coating is performed, and the carrier 3 cannot be completely fixed. In addition, if it takes too much time to start curing, the productivity is lowered. In the present embodiment, the used carrier has an average particle diameter of 50 μm, and the adhesive is cured by rotating at about 10000 rpm for 60 seconds to a film thickness of about 20 μm and fixing the carrier to the sample substrate 1.

  After applying the adhesive 2, the process proceeds to the carrier fixing step 6. The sample substrate 1 is removed from the base 13, and the carrier 3 is sprinkled on the adhesive layer before the adhesive 2 is cured. The adhesive 3 is completely cured in a state where it is piled up as much as possible, that is, it is left until it reaches the maximum strength. In this embodiment, it is set for 24 hours.

  Thereafter, as shown in FIG. 4, the sample substrate 1 is placed in the folder 19 so that the perpendicular of the sample surface of the sample substrate 1 is perpendicular to the rotation axis 18 with the rotor 17 for centrifugation. A receiving substrate 21 is installed through a hollow center part such as a spacer 20 so as to be parallel to the substrate 1, and a sufficient number of revolutions is given to the rotor 17. In this case, it is preferable to give the maximum rotation speed of the centrifuge to be used. The centrifuge used in this embodiment is CP100MX manufactured by Hitachi Koki (maximum rotational speed: 100,000 rpm, maximum centrifugal acceleration 803,000 × g), and the rotor is an angle rotor P100AT manufactured by Hitachi Koki (maximum rotational speed: 100,000 rpm, maximum). Centrifugal acceleration 803,000 × g) was used.

  It is possible to remove the excess carrier 3 that is not in contact with the adhesive 2 by the centrifugal force generated by the centrifugal separation, and to prevent the toner 4 from being separated from the sample substrate 1 when performing the centrifugal separation. Can do. Calculation of the magnitude of the centrifugal force will be described later. Thus, a state in which only the carrier is fixed can be created.

  After the excess carrier 3 is removed, the toner adhesion process 7 is reached. In this step, the operation of attaching the toner 4 to the sample substrate 1 on which the carrier 3 is sufficiently fixed is performed.

  In the toner attaching step 7, the charged toner 4 is attached to the carrier of the sample substrate 1. The carrier 3 and the toner 4 are usually triboelectrically charged in the developing unit, and each is attached with a charge of opposite polarity. Therefore, first, the carrier 3 and the toner 4 are triboelectrically charged in advance to produce a normal developer 22.

  After that, as shown in FIG. 5, the sample substrate 1 was attached to the bottom of the container 23, the developer 22 was put thereon, the container 23 was vibrated, and the developer 22 and the carrier 3 were combined. As a result, the toner 4 moves on the carrier 3 and the same conditions as those for the developer 22 can be created. In addition, as a result of measuring the charge amount of the toner on the sample substrate 1 to which the developer 22 and the toner 4 are adhered using E-SPART (Hosokawa Micron), the same state as the developer state within the error range is obtained. It was confirmed that the above 1 can be reproduced.

  After performing the toner adhesion step 7, the substrate 1, which is a measurement sample prepared as shown in FIG. 4, which enters the centrifugal separation step 8, and the receiving substrate 21 are placed on the centrifugal rotor 17 through the spacer 20. The sample 17 is placed in the folder 19 so that the perpendicular to the sample surface is perpendicular to the rotation axis 18, and the rotor 17 is rotated. At this time, one place mark or the like is put in advance on the substrate 1 and the receiving substrate 21, and the orientation is always matched when the folder 19 is put. Further, it is preferable that the distance between the receiving substrate 21 and the measurement sample substrate 1 is reduced. In this embodiment, it is 2 mm. This is because after the toner 4 is separated from the carrier 3 during the centrifugal separation, the toner 4 does not go completely in the vertical direction but tends to go in the direction opposite to the rotational direction.

When the centrifugal separator is driven and the rotor 17 is rotated, the powder in the measurement cell receives a centrifugal force corresponding to the size and mass of each. A schematic diagram is shown in FIG. Fa is adhesive force, Fc is centrifugal force (centrifugal
force). The toner 4 on the measurement sample surface 1 receives a centrifugal force corresponding to the number of rotations, and when the centrifugal force acting on the toner 4 becomes larger than the adhesion force on the measurement sample surface 1, the receiving substrate from the measurement sample surface 1 The toner 4 moves to 21. The centrifugal force received by the particles of mass m (kg) is expressed by the equation (1) using the rotational speed f (rpm) of the rotor and the r (m) of the distance 24 from the rotating shaft 18 to the toner 4 on the measurement sample substrate 1. ).

F = m × r × (2πf / 60) ² (1)
Here, the mass m (kg) of the powder is the true specific gravity ρ (kg / kg).
m ³ ) and the equivalent circle diameter d (m) are obtained in (2).

m = (4π / 3) × ρ × (d / 2) ³ (2)
In the centrifugal separation step 8, the receiving substrate 21 is changed at every constant rotation speed. At this time, the number of rotations of the rotor of the sample to be measured is determined, but the size of each toner 4 on the receiving substrate 21 can be reliably recognized, that is, the toners 4 are not overlapped. It must be in an independent state. This is because the adhesive force cannot be estimated unless the particle diameter of the toner 4 can be measured accurately. In other words, since there was a possibility that toner that had been independent before separation would overlap due to toner movement while adhering to the receiving substrate at the time of separation, the rotational section was determined finely and received each time. It is preferable to change the substrate.

  In addition, it is preferable that a material having a uniform surface is affixed to the substrate 21 so that the image collection step 9 and the image analysis step 10 can be easily performed. In this measurement, cast coated paper was used. Metals such as aluminum are easily affected by light, and paper with rough fibers is not preferable because toner enters the fibers and images cannot be captured well.

  The centrifugal separation process 8 changes the rotation speed from a low rotation speed to a high rotation speed, and after changing the receiving substrate 21 at each rotation speed, the image collection process 9 is started.

  The image collecting process 9 is a process of collecting the toner 4 image on the receiving substrate 21. In the toner attaching step 7, there are toner 4 and the like entering the shadow of the carrier 3, and it is difficult to accurately grasp the state of the sample substrate 1, so it is difficult to accurately quantify the amount of adhesion from the change in the sample substrate 1. is there. Therefore, it is necessary to calculate the adhesion force from the separated toner 4 on the receiving substrate 21 instead of calculating the adhesion force from the change of the adhesion amount on the measurement sample substrate 1 for each rotation number.

  Therefore, in the present measuring method, as described above, the sample substrate 1 and the receiving substrate 21 are marked in advance, and the toner 4 separated from the receiving substrate 21 and the measuring sample substrate 1 is adhered to the receiving substrate 21 and the measuring sample substrate 1 by centrifuging them. Since the locations to be linked have a corresponding relationship, the separation amount of the toner 4 can be received from the substrate 21. This becomes a more accurate value as the distance between the receiving substrate 21 and the measurement sample substrate 1 is shorter, and the deviation in the horizontal direction of the substrate is almost negligible.

  Needless to say, repeating the measurement increases the accuracy from the reproducibility.

  The image collection is performed using an optical microscope and a photographing means for photographing an image of the powder on the receiving substrate 21 obtained through the optical microscope. At that time, if a fixing table for positioning is designed on the sample table, and the image is taken by placing the receiving substrate 21 on the fixed table, the image of the separated toner 4 from a predetermined position on the measurement sample substrate 1 is obtained. Can be collected.

  And the image collection process 9 is complete | finished by taking in all the images of the receiving substrate 21 for each rotation speed.

  Next, an image analysis process 10 for extracting information on the toner 4 using the captured image is performed. Here, the circle-equivalent diameter of the toner 4 on the image is extracted using all image processing software. Most image processing software has functions such as binarization or color extraction, so that it can be processed without much trouble. At this time, if there is a lot of roughness or the like on the receiving substrate 21, the image processing is relatively time-consuming and correction may be required, so that the material having a uniform surface is attached to the receiving substrate 21 as described above. And preferred. In the present embodiment, cyan toner is extracted using image processing software WinRoof, and the equivalent circle diameter of each toner is obtained.

  The final adhesion calculating step 11 is performed using the equivalent circle diameter of the toner taken out in the image analyzing step 10.

  By substituting the equivalent circle diameter (m) taken out in the above formulas (1) and (2), the rotational speed (rpm) at that time, and the true specific gravity ρ of the toner 4, the adhesion force of the toner 4 per particle is obtained. Can be calculated. In this embodiment, the value of the adhesion force is the value of the centrifugal force with respect to the rotational speed of the rotor 17 in the adhesion force measurement when the toner is separated and the rotor in the previous adhesion measurement where the toner 4 is not separated. The average value of the centrifugal force value with respect to the rotational speed of 17 was defined as the value of the adhesion force of the toner. The above is the adhesion force calculating step 11 for each toner 4.

  Therefore, the common logarithm value of each estimated adhesive force is taken to create an adhesive force distribution. FIG. 7 is a distribution diagram obtained from the common logarithm of the adhesive force. The number distribution is displayed with the adhesive force on the horizontal axis and the frequency on the vertical axis. From the result of the adhesion distribution, it can be confirmed that there is a tendency in the adhesion, and it can be confirmed that it is distributed in a wide range. The average adhesion force F is calculated using Equation (3).

F = 10 ^A A = Σlog (F _i ) / (3)
Here, A is the number average common logarithmic value divided by the number N of toner from the sum of the common logarithm of the adhesion force F _i for each toner. The average adhesion force F was defined as 10 times A.

  By performing the above series of operations, the adhesion force between the carrier and the toner can be measured.

  Next, each of the carrier and the toner, which is a developer suitably used in the present invention, will be described. The carrier and toner used in the present invention have a composition known per se.

  The magnetic carrier used in the present invention will be described.

  In the present invention, a known carrier such as a magnetic material-dispersed resin carrier or a magnetic carrier of a single magnetic material such as ferrite coated on the surface can be used as the magnetic carrier. In particular, in order to obtain high-quality image formation, it is preferable to use a more stable spherical magnetic carrier. Furthermore, in order to make it possible to permanently maintain the fine irregularities on the surface of the magnetic carrier, a thermosetting binder resin is used, a thermosetting binder resin and a metal oxide are formed, and a direct polymerization method is used. It is preferable to use a magnetic carrier obtained by

  Hereinafter, this method will be described.

  As a method for obtaining magnetic material dispersed resin carrier particles, which is a preferred form of the above magnetic carrier particles, a binder resin monomer and a metal oxide containing at least magnetic fine powder are mixed and polymerized to obtain a magnetic carrier directly. A method is mentioned. As monomers used for polymerization at this time, in addition to vinyl monomers exemplified in the case of forming a toner, bisphenols and epichlorohydrin as starting materials for epoxy resins, phenols and aldehydes as starting materials for phenol resins Urea and aldehydes as starting materials for urea resins, melamine and aldehydes as starting materials for melamine resins, and the like are used. For example, when producing magnetic carrier particles used in the present invention using a thermosetting phenol resin as a binder resin, in an aqueous medium, phenols and aldehydes as raw materials are present in the presence of a basic catalyst. It can be produced by mixing and polymerizing a metal oxide, preferably a lipophilic metal oxide.

  Further, in the present invention, the magnetic carrier particles formed as described above are coated with a coating resin appropriately selected in accordance with the charge amount of the toner, and the two-component developer of the present invention is optimally charged. In addition, it is preferable to have a charge amount. The amount of the coating resin at this time is preferably in the range of 0.1 to 10% by mass. It is necessary to adjust the coating amount and the coating state so as to have the desired charge amount. As the coating resin, a thermosetting silicone resin or the like can be used.

  As the coating resin that can be used above, an insulating resin can be suitably used. The insulating resin may be a thermoplastic resin or a thermosetting resin. Specifically, for example, thermoplastic resins include acrylic resins such as polystyrene, polymethyl methacrylate, styrene-acrylic acid copolymer, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, vinyl chloride, vinyl acetate. , Polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, petroleum resin, cellulose, cellulose acetate, cellulose nitrate, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose Cellulose derivatives such as novolak resin, low molecular weight polyethylene, saturated alkyl polyester resin, polyethylene terephthalate, polybutylene Terephthalate, aromatic polyester resins such as polyacrylate, polyamide resins, polyacetal resins, polycarbonate resins, polyethersulfone resins, polysulfone resins, polyphenylene sulfide resins, polyether ketone resins.

  Specific examples of such curable resins include phenolic resins, modified phenolic resins, maleic resins, alkyd resins, epoxy resins, acrylic resins, and specific examples such as maleic anhydride-terephthalic acid-polyethylene. Unsaturated polyester obtained by polycondensation of polyhydric alcohol, urea resin, melamine resin, urea-melamine resin, xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, gliptal resin, furan resin, silicone resin, Examples thereof include a polyimide resin, a polyamideimide resin, a polyetherimide resin, and a polyurethane resin. The above-described resins can be used alone or in combination. In addition, a curing agent or the like can be mixed with a thermoplastic resin and cured for use. Further, a curing agent or the like may be mixed with the thermoplastic resin and cured.

Magnetite, ferrite, etc. represented by the general formula of MO · Fe ₂ O ₃ or MFe ₂ O ₄ can be preferably used as the magnetic fine particles used in producing the above-mentioned magnetic material dispersion type resin carrier. . Here, M is a divalent or monovalent metal, and examples thereof include Mn, Fe, Ni, Co, Cu, Mg, Zn, Cd, and Li. M may be a single metal or a plurality of metals. Specific examples of the magnetic fine particles include magnetite, γ iron oxide, Mn—Zn ferrite, Ni—Zn ferrite, Mn—Mg ferrite, Ca—Mg ferrite, Li ferrite, Cu—Zn ferrite, and the like. Can be used.

Further, in addition to the above magnetic metal oxides, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni are used as materials for producing a magnetic material dispersion type resin carrier. , Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Ba, Pb, or other nonmagnetic metal oxides using one or more metals can be used. Specifically, for example, nonmagnetic metal oxides such as Al ₂ O ₃ , SiO ₂ , CaO, TiO ₂ , V ₂ O ₅ , CrO ₂ , MnO ₂ , Fe ₂ O ₃ , CoO, NiO, CuO, ZnO, SrO, Y ₂ O ₂ , ZrO _{2 and the} like can be used.

  Next, the toner used in the present invention can be used by a known production method such as a production method by pulverization and a production method by a polymerization method such as a suspension polymerization method.

  As the binder resin of the toner used when the toner is produced by a pulverization method, polystyrene; a styrene-substituted homopolymer such as poly-p-chlorostyrene and polyvinyltoluene; a styrene-p-chlorostyrene copolymer; Styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer Polymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Styrene-based copolymer such as polymer Body, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resins, polyester resins, polyamide resins, furan resins, epoxy resins, xylene resins.

  These resins are used alone or in combination.

  As the main component of the binder resin, a styrene copolymer, which is a copolymer of styrene and another vinyl monomer, is preferable in terms of developability and fixability.

  As comonomer for styrene monomer of styrene copolymer, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, doditer acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, Monocarboxylic acid having a double bond such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substituted product thereof; maleic acid, butyl maleate, methyl maleate, Dicarboxylic acids having a double bond such as dimethyl maleate and substituted products thereof; vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene Vinyl methyl ketone, vinyl ketones such as vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether. These vinyl monomers are used alone or in combination of two or more.

  The styrene copolymer is preferably crosslinked with a crosslinking agent such as divinylbenzene in order to widen the fixing temperature range of the toner and improve the offset resistance.

  As the polymerizable monomer used when the toner is produced by the polymerization method, a vinyl polymerizable monomer capable of radical polymerization is used. As the vinyl polymerizable monomer, a monofunctional polymerizable monomer or a polyfunctional polymerizable monomer can be used.

  Monofunctional polymerizable monomers include styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butyl. Styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p -Styrene derivatives such as phenylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2 -Ethylhexyl acrylate acrylic polymerizable monomers such as n-octyl acrylate, n-nonyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethyl phosphate ethyl acrylate, diethyl phosphate ethyl acrylate, dibutyl phosphate ethyl acrylate, 2-benzoyloxyethyl acrylate; Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate , N-nonyl methacrylate, diethyl phosphate ethyl methacrylate Methacrylic polymerizable monomers such as dibutyl phosphate ethyl methacrylate; methylene aliphatic monocarboxylic acid esters; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl formate; vinyl methyl ether Vinyl ether such as vinyl ethyl ether and vinyl isobutyl ether; vinyl ketone such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropyl ketone.

  Examples of polyfunctional polymerizable monomers include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and tripropylene. Glycol diacrylate, polypropylene glycol diacrylate, 2,2'-bis (4- (acryloxy-diethoxy) phenyl) propane, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene Glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol Rudimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2′-bis (4- (methacryloxydiethoxy) phenyl) propane, Examples include 2,2′-bis (4- (methacryloxy / polyethoxy) phenyl) propane, trimethylolpropane trimethacrylate, tetramethylolmethane tetramethacrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.

  Further, the above monofunctional polymerizable monomers are used alone or in combination of two or more, or the above monofunctional polymerizable monomers and polyfunctional polymerizable monomers are used in combination. The polyfunctional polymerizable monomer can also be used as a crosslinking agent.

  As the polymerization initiator used in the polymerization of the polymerizable monomer described above, an oil-soluble initiator and / or a water-soluble initiator is used. For example, as the oil-soluble initiator, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile) Azo compounds such as 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile; acetylcyclohexylsulfonyl peroxide, diisopropylperoxycarbonate, decanonyl peroxide, lauroyl peroxide, stearoyl peroxide, propionyl peroxide Oxide, acetyl peroxide, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, t-butylperoxyisobutyrate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumylper Kisaido, t- butyl hydroperoxide, di -t- butyl peroxide, include peroxide initiators such as cumene hydroperoxide.

  Water-soluble initiators include ammonium persulfate, potassium persulfate, 2,2′-azobis (N, N′-dimethyleneisobutyroamidine) hydrochloride, 2,2′-azobis (2-aminodinopropane) hydrochloric acid Salts, sodium azobis (isobutylamidine) hydrochloride, sodium 2,2′-azobisisobutyronitrile sulfonate, ferrous sulfate or hydrogen peroxide.

  In order to control the degree of polymerization of the polymerizable monomer, a chain transfer agent, a polymerization inhibitor and the like can be further added and used.

  As the crosslinking agent used in the toner, a compound having two or more polymerizable double bonds is used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate; divinylaniline; And divinyl ether, divinyl sulfide, divinyl sulfone and other divinyl compounds; and compounds having three or more vinyl groups. These are used alone or as a mixture.

  As the release agent used for the toner, polymethylene wax such as paraffin wax, polyolefin wax, microcrystalline wax, Fischer tropish wax, amide wax, higher fatty acid, long chain alcohol, ketone wax, ester wax and graft thereof Derivatives such as compounds and block compounds may be mentioned, and distillation or the like may be performed as necessary.

  Further, the colorant used in the toner is carbon black, a magnetic material, and a black colorant that is toned in black using the following yellow / magenta / cyan colorant.

  As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complex methine compounds, and allylamide compounds are used as pigments. Specifically, C.I. I. Pigment Yellow 3.7.10.12.12.14.15.17.3.23.24.60.62.7.74.75.58.3.93.95.99.9.100.101.104.108.109.110. 111.117.123.128.129.138.139.147.148.150.166.168.169.177.179.180.181.183.185.191: 1.191.192.193.199 etc. Are preferably used. Examples of the dye system include C.I. I. solvent Yellow 33.567.79.93.112.162.163, C.I. I. disperse Yellow 42.64.2011.211 etc. are mentioned.

  As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 122, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254, C.I. I. Pigment Bio Red 19 is particularly preferable.

  As the cyan colorant, phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like are particularly preferably used.

  These colorants can be used alone or in combination and further in the form of a solid solution.

  The toner used in the present invention may use either positive charge controllability or negative charge controllability.

  The following substances are used for controlling the toner to be negatively charged.

  For example, organometallic compounds and chelate compounds are effective, and there are monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic acids, and dicarboxylic acid-based metal compounds. Others include aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, phenol derivatives such as bisphenol, and the like.

  Furthermore, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, calixarene, resin charge control agents, and the like can be given. The following substances are used to control the toner to be positively charged.

  Modified products of nigrosine by nigrosine and fatty acid metal salts, quaternary ammonium salts such as guanidine compounds, imidazole compounds, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate and the like Some onium salts such as phosphonium salts and their lake pigments, triphenylmethane dyes and these lake pigments , Ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate Dioctyl tin borate, diorgano tin borate such as dicyclohexyl tin borate, resin charge control agent and the like. These can be used alone or in combination of two or more.

  The charge control agent is used in an amount of 0.01 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the binder resin. When the toner of the present invention is a polymerization toner, a condensation resin may be added.

  Examples of the condensation resin of the present invention include polyester, polycarbonate, phenol resin, epoxy resin, polyamide, and cellulose. More preferably, polyester is desired because of the variety of materials. It is good to use 0.01-20 mass parts per 100 mass parts binder resin, More preferably, 0.5-10 mass parts is used.

  The additive for the purpose of improving various properties in the toner preferably has a particle size of 1/2 or less of the volume average diameter of the toner particles from the viewpoint of durability. The particle size of the additive means the average particle size obtained by observing the surface of the toner particles with an electron microscope. As additives for the purpose of imparting these characteristics, for example, the following are used.

  Examples of the fluidity-imparting agent include metal oxides (silicon oxide, aluminum oxide, titanium oxide, etc.) carbon black, carbon fluoride, and the like. Those subjected to hydrophobic treatment are more preferable.

  As abrasives, metal oxides (strontium titanate, cerium oxide, aluminum oxide, magnesium oxide, chromium oxide, etc.), nitrides (silicon nitride, etc.), carbides (silicon carbide, etc.), metal salts (calcium sulfate, barium sulfate, etc.) , Calcium carbonate, etc.).

  Examples of the lubricant include fluorine-based resin powder (vinylidene fluoride, polytetrafluoroethylene, etc.), fatty acid metal salts (zinc stearate, calcium stearate, etc.) and the like.

  Examples of the charge controllable particles include metal oxides (tin oxide, titanium oxide, zinc oxide, silicon oxide, aluminum oxide, etc.), carbon black, and the like.

  These additives are used in an amount of 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts by weight of toner particles.

  These additives may be used alone or in combination. Furthermore, you may hydrophobize (oil, coupling) as needed.

  The toner production method of the present invention will be described below.

  When the toner used in the present invention is a pulverized toner, at least a binder resin and a colorant are kneaded and uniformly dispersed using a pressure kneader, an extruder, or a media disperser. Manufacturing to produce toner particles by mechanically or colliding with a target under a jet stream to finely pulverize to a desired toner particle size, and after passing through a classification step, the desired circularity is obtained using mechanical means. And a method of performing a wet or dry thermal spheronization after the above-mentioned fine pulverization.

  When the toner used in the present invention is a polymerization method, there is no particular limitation, but a suspension polymerization method that can easily obtain toner particles having a small particle diameter is particularly preferable. Furthermore, a seed polymerization method in which a monomer is further adsorbed to the obtained polymer particles and then polymerized using a polymerization initiator can be suitably used in the present invention. At this time, it is possible to disperse or dissolve a polar compound in the monomer to be adsorbed.

  In the case of suspension polymerization, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition. Examples of the dispersant used include inorganic calcium oxide, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, Examples include calcium sulfate, barium sulfate, bentonite, silica, alumina, and sodium dodecyl sulfate. As the organic compound, for example, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch and the like are used. These dispersing agents or dispersing aids are preferably used in an amount of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer. You may use 0.001-0.1 mass% surfactant in order to refine | miniaturize these dispersing agents. Specifically, commercially available nonionic, anionic and cationic surfactants can be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate and the like are preferably used.

  Using a non-magnetic toner with an average particle diameter of 6.8 μm produced by a pulverization method and a magnetic carrier with an average particle diameter of 50 μm, a developer having a toner concentration of 8 wt% is prepared and subjected to a centrifugal separation method. The developer adhesion used was measured, and a solid image was created as a printing durability test. At this time, the toner charge amount was Q / M = 52 [μC / g], and the average adhesive force was F = 24 [nN]. In the printing durability test, an image was created using the image forming apparatus shown in FIG.

  Here, the developing conditions of the image forming apparatus used for the printing durability test will be described.

  FIG. 8 is a schematic diagram illustrating a developing unit of the image forming apparatus used in the embodiment. The developing device includes a developing container 25, a developing sleeve 26, a developer returning member 27, and a blade 28, and is disposed to face the photosensitive drum 29.

  In the developing chamber 30 and the agitating chamber 31, an agitating screw 32 and an agitating screw 33 are arranged as developer conveying means, respectively. The agitating screw 32 agitates and conveys the developer in the developing chamber 30, and the agitating screw 33 is supplied from a toner supply tank (not shown) under the control of a developer concentration control device (not shown). The toner supplied to the upstream side of the agitating screw 33 and the developer already in the agitating chamber 31 are agitated and conveyed to uniformize the toner concentration.

  The partition wall 34 is provided with a developer passage (not shown) that allows the developing chamber 30 and the agitating chamber 31 to communicate with each other, and the developer in the developing chamber 30 in which the toner is consumed by the development and the density is lowered. However, it is configured to move from one passage of the partition wall 34 into the stirring chamber 31 by the conveying force of the stirring screw 32 and the stirring screw 33.

  The developing chamber 30 of the developing device has an opening at a portion facing the photosensitive drum 29, and is rotatably arranged so that the developing sleeve 26 is partially exposed to the opening. The developing sleeve 26 is formed of a nonmagnetic material and rotates in the direction of the arrow in the drawing during the developing operation. Inside the developing sleeve 26, a magnet (magnet roller) 35 as a magnetic field generating means is fixedly arranged.

  The developer in the developing chamber 30 is supplied to the surface of the developing sleeve 26 by the stirring screw 32 and is carried on the surface of the developing sleeve 26 in the form of a magnetic brush by the magnetic force of the magnet roller 35. The developer carried on the developing sleeve 26 is conveyed to a developing area facing the photosensitive drum 29 by the rotation of the developing sleeve 26. During the conveyance, the developer on the developing sleeve 26 is regulated by the developer return member 27 and the blade 28, so that the amount of the developer conveyed to the development region is properly maintained.

  The developer conveyed to the development area is used for developing the latent image formed on the photosensitive drum 29. In order to improve the developing efficiency, that is, the application rate of toner to the latent image, a developing bias voltage in which an AC voltage is superimposed on a DC voltage is applied to the developing sleeve 26 from a power source 36.

  More specifically, the magnet roller 35 in the developing sleeve 26 has a five-pole configuration, and the developer supplied by the stirring screw 32 is restrained on the surface of the developing sleeve 26 by the magnetic force of the conveying magnetic pole (pumping pole) S2. The developer is held and carried and conveyed to the developer reservoir 37 by the rotation of the developing sleeve 26. The amount of the developer is regulated by the developer return member 27, and the developer is sufficiently applied on the surface of the developing sleeve 26 by the conveying magnetic pole (cut pole) N2 having a magnetic flux density of a certain level or more necessary for stable restraint. Restrain and form a magnetic brush.

  Next, the magnetic brush is trimmed by the blade 28 to further regulate the amount of developer to an appropriate amount, and the developer is transported toward the developing region by the transport magnetic pole S1.

  Next, in the developing region, under the formation of the developer magnetic brush by the developing pole Nl, an alternating voltage in which an AC voltage is superimposed on a DC voltage is applied as a developing bias from the bias power source 36 to the developing sleeve 26, and the magnetic brush The toner is transferred onto the photosensitive drum 29, the toner is attached to the latent image on the photosensitive drum 29 and developed, and the latent image is visualized as a toner image. In the embodiment, the image was formed with the distance between the developing sleeve 26 and the drum 29 being 400 μm and the developing contrast being 250V.

  The obtained image had a uniform density and a sufficient loading amount. Furthermore, the graininess of the image was good and good image formation could be performed. The reason for this is that the charge amount is sufficiently high while the adhesive force is small, so that a sufficient amount of toner moves to the photosensitive drum during toner flight, and the action of the electric field is faithful due to the high charge amount. It can be said that it moved to the drum. It can be said that a high-quality image can be obtained by this effect.

<Comparative Example 1>
In order to demonstrate the effects in the examples, the following six developers were prepared as comparative experiments. All of the toners used had an average particle diameter of 6.8 μm, and the carrier had an average particle diameter of 50 μm.

  (Developer 1) Carrier A and toner A were mixed to prepare a developer having a toner concentration ratio of 8 wt%. The charge amount at this time was Q / M = 28 [μC / g], and the average adhesion was F = 25 [nN]].

  (Developer 2) Carrier B and toner A were mixed to prepare a developer having a toner concentration ratio of 8 wt%. At this time, the charge amount was Q / M = 54 [μC / g], and the average adhesive force was F = 37 [nN].

  (Developer 3) Carrier B and toner B were mixed to produce a developer having a toner concentration ratio of 8 wt%. At this time, the charge amount was Q / M = 42 [μC / g], and the average adhesion was F = 28 [nN].

  (Developer 4) Carrier C and toner B were mixed to prepare a developer having a toner concentration ratio of 8 wt%. The charge amount at this time was Q / M = 38 [μC / g], and the average adhesion was F = 20 [nN].

  (Developer 5) Carrier C and toner A were mixed to prepare a developer having a toner concentration ratio of 8 wt%. The charge amount at this time was Q / M = 56 [μC / g], and the average adhesion was F = 26 [nN].

  (Developer 6) Carrier A and toner B were mixed to prepare a developer having a toner concentration ratio of 8 wt%. At this time, the charge amount was Q / M = 48 [μC / g], and the average adhesion was F = 17 [nN].

  The contrast was set to 250 V for each as in the example.

(Result of developer 1)
The amount of toner on the image was good because the charge amount was low. However, it became a result that a lot of crunch came out.

(Result of developer 2)
Since the charge amount was high and the adhesive force was also high, a sufficient loading amount could not be obtained at a contrast of 250 V, resulting in a low density image.

(Results of developers 3, 5, 6)
Despite the high charge amount, an image with good graininess could be formed with a sufficient amount of application and small roughness.

(Result of developer 4)
As in the case of the developer 1, a sufficient loading amount could be obtained, but the roughness was so great that the image formation could not be said to be satisfactory.

  FIG. 9 shows the relationship between the charge amount and the adhesive force of the developers used in Examples and Comparative Examples, and the results of image formation. From these results, it was confirmed that good image formation was possible in the areas of the developers 3, 5 and 6 of the examples and comparative examples.

  From these results, the toner average charge amount Q / M [μC / g] is 40 [μC / g] to 60 [μC / g], and the toner average adhesion is in the range of 15 [nN] to 30 [nN]. It was judged that good image formation was possible when it was in the range, and it was judged impossible in other ranges. The reason for the impossibility is that when Q / M is larger than 60 [μC / g], the loading amount decreases, and when it is 40 [μC / g] or less, the loading amount is good. However, the image is not high quality. In the case where the adhesive force is 30 [nN] or more, it is difficult to separate the toner from the carrier.

  From the above, it was confirmed that high image quality can be obtained by satisfying the conditions described in the claims of the present invention.

  It is important to reduce the particle size in order to improve the image quality of electrophotography. However, reducing the particle size reduces the amount of charge of a single toner particle, which reduces electrostatic adhesion. Therefore, the contribution of the non-electrostatic adhesive force component becomes large, and control by electrostatic force becomes difficult. In order to avoid this, development with a higher charge amount is indispensable, and for that purpose, an appropriate adhesion force to toner flying is required.

  Thus, high image quality can be achieved by satisfying the conditions described in the claims of the present invention.

It is the schematic of the adhesive force measurement sample which concerns on this invention. It is a figure which shows the whole process of the adhesive force measurement which concerns on this invention. 1 is a schematic view of a spin coater according to the present invention. It is the figure which showed the schematic diagram inside the rotor of a centrifuge. It is a figure which shows the toner adhesion process which concerns on this invention. It is a figure which shows the outline of the principle of the centrifugation method. It is an adhesive force distribution map obtained by the adhesive force measurement which concerns on this invention. FIG. 2 is a schematic diagram illustrating a developing unit of an image forming apparatus used in an embodiment of the present invention. FIG. 5 is a diagram illustrating adhesion force, charge amount, and image formation results of developers prepared in Examples and Comparative Examples of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sample substrate 2 Adhesive 3 Carrier 4 Nonmagnetic toner 12 Spin coater 13 Base 14 Motor 15 Power supply image value 16 Cover 17 Rotor 18 Rotating shaft 19 Folder 20 Spacer 21 Receiving substrate 22 Developer 23 Container 24 Distance 25 Developer container 26 Development Sleeve 27 Development return member 28 Blade 29 Photosensitive drum 30 Developing chamber 31 Stirring chamber 32 Stirring screw 33 Stirring screw 34 Partition 35 Magnet roller 36 Power source 37 Developer reservoir

Claims (6)

An electrophotographic two-component developer comprising a toner and a magnetic carrier, wherein the development is performed using the two-component developer.
The toner average charge amount Q / M [μC / g] of the toner is 40 [μC / g] to 60 [μC / g], and the average adhesion force of the toner to the magnetic carrier is determined by a centrifugal separation method. The two-component development method according to claim 1, wherein the method is in the range of 15 [nN] to 30 [nN].   The distance between the developing sleeve and the image carrier such as a photosensitive drum is in the range of 100 [μm] to 700 [μm], and an alternating electric field is applied to the DC bias component between the developing sleeve and the image carrier such as the photosensitive drum. The two-component developing method according to claim 1, wherein:   2. The two-component developing method according to claim 1, wherein the magnetic carrier of the two-component developer has an average volume particle size of 50 [mu] m or less.   2. The two-component developer method according to claim 1, wherein the magnetic carrier is obtained by coating the surface of magnetic particles (core material) made of iron, magnetite, nickel, ferrite or the like with a resin coating layer.   2. The two-component developing method according to claim 1, wherein the adhesive force is measured using a centrifugal separation method.   The centrifuge method includes a centrifuge having a rotor that can be installed so that the perpendicular of the sample surface of the sample substrate on which one kind of adherent material particles are uniformly fixed is perpendicular to the rotation axis, and the centrifuge Attaching the powder is characterized by measuring the adhesion force between the powder consisting of at least one kind of fine particles and the adherend material particles on the sample substrate with centrifugal force generated by the rotation of the apparatus. When fixing the adherent particles on the sample substrate in the adhesion measuring method and apparatus, the adhesive layer is formed by means for uniformly applying the thickness of the adhesive layer to a layer thinner than the adherent particle diameter. The method is performed by a method and an apparatus for measuring the adhesive force of powder, characterized in that a sample in which the adherend particles are embedded in a single layer and the powder made of the fine particles is adhered to the exposed portion of the adherend particles is used. Special features Two-component developing method in claim 1, wherein.

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