JP4208679B2 - Two-component developer and developing device - Google Patents

Description

  The present invention relates to a developing device such as a copying machine, a printer, and a facsimile, and a two-component developer used in the developing device.

  2. Description of the Related Art Conventionally, in a developing device that performs development using a two-component developer using toner and a carrier, a developing device that takes in toner into the developer by the movement of the developer without requiring a toner density detecting means is known. ing. However, in this developing device, the amount of toner taken in differs between a portion where the developer moves actively and a portion where the developer is not moving, or a portion where the developer is high and low, and the toner concentration is partially unstable. As a result, image density unevenness and fogging were likely to occur.

  As a method for solving this problem, a developing sleeve that has a magnetic field generating means inside and carries and conveys a two-component developer containing toner and a magnetic carrier, and is carried and carried by the developing sleeve. A first regulating member that regulates the amount of the developer; a developer containing unit that contains the developer scraped off by the first regulating member; and a developer containing unit adjacent to the developer containing unit, on the developing sleeve A toner container for supplying the toner, and a change in the toner density of the developer on the developing sleeve changes the contact state between the developer and the toner, thereby taking in the toner in the developer on the developing sleeve Has been proposed (see, for example, Patent Document 1).

  Further, as a means for preventing the early deterioration of the two-component developer that occurs in the developing device, a developing device that promotes replacement of the developer on the developing sleeve and the developer in the developer accommodating portion has been proposed (for example, , See Patent Document 2 and Non-Patent Document 1).

  However, in the above-described apparatus, if the developer amount is increased to achieve a longer life, the remaining developer moves rapidly except for the one passing through the gap between the developer pre-formed member and the developing sleeve. It becomes difficult to supply new toner to the developer that contributes to the development. Since the amount of the developer cannot be increased in this way, the replenished toner cannot be sufficiently charged, for example, when printing with a high image area ratio is continuously performed over a long period of time, and internal contamination due to toner scattering is prevented. And image defects such as fogging may occur.

Japanese Patent Laid-Open No. 9-22178 (page 25, FIG. 1 to FIG. 5) JP 2001-166580 A (page 6-11) Ricoh Technical Report No27 November, 2001, page 2-3

  A first object of the present invention is to provide a two-component developer and a developing device that can sufficiently charge the toner of a developer even when a printed image having a high image area ratio is continuously performed over a long period of time. It is.

  The second object is to optimize the developer capacity in the developer container so as to reduce image density, increase image density due to insufficient toner charging, and cause scumming and toner scattering. It is an object of the present invention to provide a two-component developer and a developing device that can be prevented.

  A third object of the present invention is to provide a two-component developer and a developing device that can self-control the toner concentration of the developer without being influenced by the environment and can extend the life of the developer. .

In order to achieve the first object, in the two-component developer of the present invention, the magnetic toner and the magnetic carrier in the developer accommodating portion are rotated while the developing sleeve having the magnetic field generating means is rotated. The developer containing the developer is transported while regulating the transport amount toward the developing region by the developer regulating member on the downstream side in the developer carrying direction of the developer accommodating portion, and the developer blocked by the developer regulating member. A developer containing portion for containing the toner, and a magnetic toner containing portion having a magnetic toner replenishing opening facing the surface of the developing sleeve at a position adjacent to the developer containing portion from the upstream side in the developer transport direction. by the movement of the developer due to the developer conveying the above is a developing apparatus incorporated into a developer accommodating portion of the magnetic toner in the magnetic toner container according to the capacity of the developer accommodating portion of the developer,
A second regulating member for regulating the amount of developer carried on the developing sleeve is provided in the vicinity of the magnetic toner replenishing opening of the developer accommodating portion so as to face the developing sleeve. The lower surface of the opening is formed so as to be inclined downward toward the developing sleeve side, and when the magnetic toner concentration in the developer containing portion is high, the developer overflows into the magnetic toner replenishing opening, In the two-component developer used in the developing device in which the magnetic toner is supplied from the magnetic toner replenishing opening to the developer containing portion when the magnetic toner concentration in the developer containing portion is low ,
Magnetic carrier is a magnetic fine particle-dispersed resin carrier containing at least a magnetic core material and the coating resin having at least inorganic compound particles and a binder resin, the total resin content is in the coating resin and the binder resin 5 to 25% by mass, the apparent density is 1.2 to 2.3 g / cm ³ , the average particle size is 25 to 55 μm, 21 μm or less is 0.01 to 12% by volume, and 72 μm or more. It is a two-component developer characterized by being 1.0% by volume or less.

In the developing device of the present invention, the developer containing the magnetic toner and the magnetic carrier in the developer accommodating portion is rotated while the developing sleeve having the magnetic field generating means is rotated inside. A developer containing member for regulating the amount of conveyance toward the developing region by the developer regulating member on the downstream side in the carrying direction and carrying the developer blocked by the developer regulating member, and the developer And a magnetic toner container having a magnetic toner replenishment opening facing the surface of the developing sleeve at a position adjacent to the container from the upstream side in the developer conveying direction, and movement of the developer accompanying the developer conveyance on the developing sleeve In the developing device for taking in the magnetic toner in the magnetic toner container according to the magnetic toner concentration of the developer on the developing sleeve,
A second regulating member for regulating the amount of developer carried on the developing sleeve is provided in the vicinity of the magnetic toner replenishing opening of the developer accommodating portion so as to face the developing sleeve. The lower surface of the opening is formed so as to be inclined downward toward the developing sleeve side, and when the magnetic toner concentration in the developer containing portion is high, the developer overflows into the magnetic toner replenishing opening, When the magnetic toner concentration in the developer accommodating portion is low, magnetic toner is replenished to the developer accommodating portion from the magnetic toner replenishing opening,
The magnetic carrier constituting the developer is a magnetic fine particle dispersed resin carrier containing at least a magnetic core material having inorganic compound particles and a binder resin and a coating resin, and the total of the coating resin and the binder resin A certain resin content is 5 to 25% by mass, an apparent density is 1.2 to 2.3 g / cm ³ , an average particle size is 25 to 55 μm, and 21 μm or less is 0.01 to 12% by volume. In addition, the developing device is characterized by using a magnetic carrier in which 72 μm or more is 1.0% by volume or less.

  In order to achieve the second object, the two-component developer further includes a magnetic fine particle dispersed resin carrier in which the magnetic core material has at least inorganic compound particles and a thermosetting phenol resin as a binder resin. It is a feature.

In order to achieve the third object, the two-component developer is characterized in that the magnetic toner has a saturation magnetization of 1.0 to 50.0 Am ² / kg. And a release member that faces the surface of the developing sleeve in a non-contact manner in the developer accommodating portion and peels off the upper layer portion of the developer carried and conveyed by the developing sleeve. .

More preferably, the two-component developer is characterized in that the magnetic toner has a saturation magnetization of 5.0 to 25.0 Am ² / kg, and the developing device uses a magnetic material as the peeling member. It is characterized by being comprised.

  According to the present invention, by using a low density coated carrier having a resin content of 5 to 25% by mass and controlling the saturation magnetization of the magnetic toner within a specific range, a simple toner concentration detecting means is not used. Even when applied to the developing method, toner deterioration and toner spent over a long period of time can be suppressed, and image stability can be achieved.

  Hereinafter, an embodiment in which the present invention is applied to a developing device of an image forming apparatus such as a copying machine, a facsimile, or a printer will be described.

  FIG. 1 is a schematic configuration diagram of a main part of the printer according to the present embodiment. In FIG. 1, a developing device 2 disposed on the side of a photosensitive drum 1 serving as a latent image carrier is a support case 10, a developing sleeve 4, a developer containing member 11, and a first developer regulating member. It is mainly composed of the first doctor blade 6 and the like.

  A support case 10 having an opening on the side of the photosensitive drum 1 forms a magnetic toner hopper 8 as a magnetic toner containing portion for containing the magnetic toner 3a. Near the photosensitive drum 1 side of the magnetic toner hopper 8, a developer accommodating member 11 that accommodates a two-component developer 3 including a magnetic toner 3 a and a carrier 3 b is provided integrally with the support case 10. . Further, the support case 10 located below the developer containing member 11 is formed with a protruding portion 10a having a facing surface 10b, and the space between the lower portion of the developer containing member 11 and the facing surface 10b A toner supply opening 20 for supplying the magnetic toner 3a is formed.

  Inside the magnetic toner hopper 8, a magnetic toner agitator 9 is disposed as magnetic toner supply means that is rotated by a drive means (not shown). The magnetic toner agitator 9 sends out the magnetic toner 3 a in the magnetic toner hopper 8 toward the magnetic toner supply opening 20 while stirring. Further, on the side of the magnetic toner hopper 8 facing the photosensitive drum 1, magnetic toner end detection means 10c for detecting when the amount of the magnetic toner 3a in the magnetic toner hopper 8 decreases is disposed. ing.

  A developing sleeve 4 is disposed in a space between the photosensitive drum 1 and the magnetic toner hopper 8. The developing sleeve 4 that is rotationally driven in the direction of the arrow in the figure by a driving means (not shown) has a magnet roller 5 as a magnetic field generating means disposed in a relative position unchanged with respect to the developing device 2. Yes.

  The first doctor blade 6 is integrally attached to the developer accommodating member 11 on the side facing the side attached to the support case 10. The first doctor blade 6 is disposed in a state where a certain gap is maintained between the tip of the first doctor blade 6 and the outer peripheral surface of the developing sleeve 4.

  A second doctor blade 7 as a second restricting member is disposed in a portion of the developer containing member 11 located in the vicinity of the toner supply opening 20. The second doctor blade 7 has a free end in a direction that obstructs the flow of the layer of the developer 3 formed on the surface of the developing sleeve 4 in order to keep a constant gap with respect to the outer peripheral surface of the developing sleeve 4, that is, free The base end is integrally attached to the developer accommodating member 11 with the end facing the center of the developing sleeve 4.

  The developer accommodating portion A is configured to have a sufficient space for circulating and moving the developer 3 within a range where the magnetic force of the magnet roller 5 in the developing sleeve 4 reaches.

  The facing surface 10b is formed over a predetermined length so as to incline downward from the magnetic toner hopper 8 side toward the developing sleeve 4 side. As a result, when vibration, uneven magnetic distribution of the magnet roller 5 provided inside the developing sleeve 4 or a partial increase in the magnetic toner concentration in the developer 3 occurs, the second doctor blade 7 and the developing sleeve 4, even if the carrier 3 b in the developer accommodating portion A falls from between the peripheral surface of the developer 4, the dropped carrier 3 b is received by the facing surface 10 b and moves toward the developing sleeve 4, and is magnetically applied to the developing sleeve 4 by magnetic force. Then, it is supplied again into the developer accommodating portion A. As a result, it is possible to prevent a decrease in the amount of the carrier 3b in the developer accommodating portion A, and it is possible to prevent occurrence of uneven image density in the axial direction of the developing sleeve 4 during image formation.

  With the above configuration, the magnetic toner 3a sent out from the inside of the magnetic toner hopper 8 by the magnetic toner agitator 9 is supplied to the developer 3 carried on the developing sleeve 4 through the magnetic toner supply opening 20 and accommodates the developer. Carried to part A. The developer 3 in the developer accommodating portion A is carried on the developing sleeve 4 and conveyed to a position facing the outer peripheral surface of the photosensitive drum 1, and only the magnetic toner 3 a is formed on the photosensitive drum 1. A magnetic toner image is formed on the photosensitive drum 1 by electrostatic coupling with the electrostatic latent image.

  Next, when the magnetic toner 3 a is set in the magnetic toner hopper 8, the toner 3 a is supplied from the magnetic toner supply opening 20 to the magnetic carrier 3 b carried on the developing sleeve 4. Therefore, the developing sleeve 4 carries the developer 3 that is a mixture of the magnetic toner 3a and the magnetic carrier 3b.

  In the developer accommodating portion A, when the capacity of the developer 3 accommodated in accordance with the magnetic toner concentration increases and decreases and the magnetic toner concentration decreases (the image density decreases), the development in the developer accommodating portion A occurs. The amount of the agent is reduced, so that the magnetic toner 3a is more fed to the developer accommodating portion through the magnetic toner supply opening 20, and the magnetic toner density is increased. On the other hand, when the magnetic toner density increases (the image density increases), the developer capacity in the developer accommodating portion A increases, and the developer overflows to the magnetic toner supply opening 20, thereby the magnetic toner 3a. Is prevented from being sent to the developer container, so that the magnetic toner density is lowered.

  As described above, the magnetic toner concentration in the developer accommodating portion changes according to the magnetic toner concentration, whereby the magnetic toner concentration in the developer accommodating portion can be kept within a certain range. As described above, according to the developing device of this embodiment, the magnetic toner concentration of the developer can be self-controlled without the need for the conventional magnetic toner replenishing mechanism and the magnetic toner concentration sensor.

  Next, the carrier and magnetic toner constituting the developer used in the developing device of this embodiment will be described.

  We investigated the spent properties of magnetic toner and external additives to the carrier in durability with a small amount of developer. As for the physical properties of the carrier, the toner with larger particle size and larger apparent density is the magnetic toner. And found that the external additives have a high spent property. This is because when the apparent density is high, the developer is strongly compressed in the developing unit, the spent property is increased, and when the particle size is large, the contact opportunity with the magnetic toner in the developing unit is increased. This is thought to increase the spent property.

  On the other hand, in order to faithfully reproduce the latent image, a toner having a smaller particle diameter must be uniformly charged, so that the contact opportunity between the magnetic toner and the carrier is increased and the spent property is increased. That is, satisfying the above-mentioned conflicting carrier characteristics can provide a two-component developer having high image quality and excellent durability.

From this point of view, we have intensively studied and found that the above problems can be solved by well controlling the particle size distribution and the apparent density of the carrier. That is, the resin-coated carrier used has a resin content of 5 to 25% by mass, an apparent density of 1.2 to 2.3 g / cm ³ , preferably 1.6 to 2.0 g / cm ³ , and an average The particle size is 25 to 55 μm, preferably 30 to 50 μm, 21 μm or less is 0.01 to 12% by volume, preferably 0.03 to 6.0% by volume, 72 μm or more is 1.0% by volume or less, Preferably, the composition satisfies 0.5% by volume or less.

  The resin-coated carrier has an average particle diameter of 25 to 55 μm so that the present invention is suitably expressed. If it is larger than 55 μm, it is insufficient to give a uniform and good charge to the magnetic toner with a small amount of developer, which causes fogging and fluctuations in image density. On the other hand, if it is smaller than 25 μm, the fluidity of the developer is likely to deteriorate, and the developer capacity does not change as expected according to the magnetic toner concentration, and as a result, the self-controllability of the magnetic toner concentration is likely to be impaired. Become.

  In addition, when the abundance on the fine particle side is large, not only the fluidity of the developer is deteriorated, the coating is likely to be non-uniform and image density unevenness is likely to occur, but also an electrostatic latent image is formed via a carrier. It becomes easy to disturb. On the contrary, when the abundance on the fine particle side is small, the flowability of the developer is good, but it becomes insufficient to give the magnetic toner uniform and good charge, and it is difficult to faithfully reproduce the latent image. As well as fogging and fluctuations in image density.

  As described above, iron powder, ferrite, and magnetite are used as the carrier ferromagnetic material in the present invention, and ferrite or magnetite is preferable. Since the iron powder carrier has a large saturation magnetization, it is easy to toner spent, and is not particularly preferable in the present invention.

An apparent density of 1.2 to 2.3 g / cm ³ is required in order to suppress the deterioration of the durable magnetic toner, which is one of the objects of the present invention, and in order to suppress carrier adhesion to the photoreceptor. The apparent density is preferably 1.5 to 2.0 g / cm ³ .

In the present invention, examples of the ferromagnetic material that can be suitably used include magnetite and ferrite having magnetism represented by the following formula (1) or (2).
MO · Fe ₂ O ₃ (1)
M · Fe ₂ O ₄ (2)
(In the formula, M represents a trivalent, divalent or monovalent metal ion.)

  Examples of M include Mg, Be, Ca, Sr, Mn, Fe, Co, Ni, Cu, Zn, Y, Rb, Zr, Nb, Mo, Cd, Pb, and Li. Can be used.

  In the present invention, particularly preferred are light metals composed of Li, Mg, Ca, and Sr, and these are preferably used alone or in combination so that the specific gravity and density can be easily controlled, but are also used in combination with other metals such as Mn. And may be adjusted by the resin content.

  Specific examples of the metal compound particles having magnetism include Ca—Mg—Fe ferrite, Li—Fe ferrite, Mn—Mg—Fe ferrite, Ca—Be—Fe ferrite, and Mn—Mg. Examples thereof include iron-based oxides such as -Sr-Fe-based ferrite, Li-Mg-Fe-based ferrite, and Li-Rb-Fe-based ferrite.

In particular, the ratio of one or more oxides selected from the group consisting of Li, Mg, Ca and Sr to Fe ₂ O ₃ in the ferrite component is 5:95 to 55:45, preferably 35: in mol%. It is suitable to be in the range of 65 to 55:45. When the ratio is out of the range, the surface state becomes difficult to control as described later, and it may be difficult to carry 5 to 25% by mass of the resin.

It is desirable to add a small amount of other metal oxides to the ferrite particles for the core material in order to control the degree of crystal growth and unevenness on the particle surface or to control the particle density. The other metal oxides are one or more oxides belonging to groups IA, IIA, IIIA, IVA, VA, IIIB and VB of the periodic table, such as BaO, Al ₂ O ₃ , TiO ₂ , SiO _2. , SnO ₂ and Bi ₂ O ₅ .

  Further, conventionally known heavy metal oxides such as CuO and ZnO may be added as a charge accelerator.

  The amount of the other metal oxide added is preferably 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the ferrite component. When the addition amount is less than 0.01 parts by mass, crystal growth tends to be low, and the particle strength tends to be low. On the other hand, when the amount exceeds 10 parts by mass, the uniformity of the composition is lost, and the production of oxides other than the ferrite composition and the production of non-magnetic or weak magnetic materials due to the reaction between the oxide and hematite are likely to occur. As a result, there is a disadvantage that carrier adhesion to the photoreceptor occurs.

  In the present invention, in order to satisfy the above apparent density, the resin content is desirably 5 to 25% by mass, and preferably 8 to 17% by mass.

  Next, a spherical magnetic fine particle dispersed resin carrier (hereinafter referred to as “resin carrier”) particularly preferably used in the present invention will be described in detail.

  The resin carrier of the present invention is preferably formed of a carrier core in which inorganic compound particles are dispersed in a binder resin, and the particle surface of the carrier core is preferably treated.

  The inorganic compound particles constituting the carrier core in the present invention may be any inorganic compound particles that do not dissolve in water or are not altered or denatured by water, and include those obtained by mixing magnetic inorganic compound particles and nonmagnetic inorganic compound particles.

  Examples of magnetic inorganic compound particles include magnetite particles, maghemite particles, particles obtained by depositing or containing cobalt therein, barium, strontium or barium-strontium-containing magnetoplumbite type ferrite particles, manganese, nickel, zinc, Various magnetic particles such as spinel ferrite particles containing one or more selected from lithium and magnesium can be used.

  Nonmagnetic inorganic compound particles include hematite particles, hydrous ferric oxide particles, titanium oxide particles, silica particles, talc particles, alumina particles, barium sulfate particles, barium carbonate particles, cadmium yellow particles, calcium carbonate particles, zinc white particles. Etc. can be used.

  As the particle form of the inorganic compound particles, particles having any form such as cubic, polyhedral, spherical, needle-like, and plate-like can be used. The 50% particle size of the inorganic compound particles may be any particle that is smaller than the 50% particle size of the magnetic carrier, and is preferably 0.02 to 5.0 μm. In particular, the 50% particle size of the magnetic inorganic compound particles is (a). When the 50% particle size of the nonmagnetic inorganic compound particles is (b), (a) is 0.02 to 2 μm, (b) is 0.05 to 5 μm, and 1.5 (a) <(B) is more preferable.

Further, the nonmagnetic inorganic compound particles have a larger volume resistance value than the magnetic inorganic compound particles, and the 50% particle size of the nonmagnetic inorganic compound particles is larger than the 50% particle size of the magnetic inorganic compound particles. It is preferable for increasing the resistance value and reducing the true specific gravity of the carrier. In particular, the nonmagnetic inorganic compound particles are preferably 10 ⁷ Ωcm or more, more preferably 10 ⁸ to 10 ¹⁴ Ωcm from the viewpoint that the resistance of the magnetic carrier can be adjusted.

  The magnetic inorganic compound particles are contained in an amount of 30 to 95% by mass with respect to the total amount of the magnetic inorganic compound particles and the nonmagnetic inorganic compound particles, thereby adjusting the magnetic force of the carrier to prevent carrier adhesion. It is preferable for adjusting the volume resistance value.

  It is also preferred that the inorganic compound particles are all or partly treated with a lipophilic agent. As the lipophilic agent, an organic compound having one or more functional groups selected from an epoxy group, amino group, mercapto group, organic acid group, ester group, ketone group, halogenated alkyl group and aldehyde group A compound or a mixture thereof can be used, and any of them can achieve the object of the present invention. Among these, a coupling agent having the above functional group is preferable, and a silane coupling agent is particularly preferable. Furthermore, as a preferable functional group, an epoxy group, an amino group, and a mercapto group are preferable in that the particle size distribution of the carrier is sharp, and further, the epoxy group makes the dispersed state of the inorganic compound particles uniform, and the temperature and humidity This is preferable in that the charge imparting ability of the carrier is stable.

  As the binder resin constituting the carrier core in the present invention, a thermosetting resin is particularly preferable.

  Thermosetting resins include phenolic resins, epoxy resins, polyamide resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, xylene resins, acetoguanamine resins, furan resins, silicone resins, polyimide resins, urethane resins. These resins may be used alone or in combination of two or more, but preferably contain at least a phenol resin.

  The surface of the carrier core used in the magnetic carrier of the present invention may be coated with a coupling agent or resin as necessary.

  The resin used for coating may be any resin as long as it is a common resin, and examples thereof include epoxy resins, silicone resins, polyester resins, fluororesins, styrene resins, acrylic resins, and phenol resins. A polymer obtained by polymerization from monomers may also be used. In view of durability and stain resistance, silicone resin is preferable.

  The coating amount of the resin covering the carrier core is preferably 0.05% by mass or more with respect to the carrier core. When the amount is less than 0.05% by mass, an insufficient and non-uniform film tends to be formed, and it becomes difficult to freely control the charge amount. On the other hand, if the coating amount is too large, the electric resistance of the magnetic carrier tends to be too high, causing problems on the image. More preferably, it is 0.1-10 mass%, More preferably, it is 0.2-5 mass% in order to prevent unity of the particles at the time of resin coating.

  If necessary, the resin covering the carrier core may contain a coupling agent in an amount of 0.1 to 20.0% by mass based on the resin solid content. As the coupling agent, a silane coupling agent is preferable. More preferably, the content is 0.1 to 10.0% by mass in order to prevent strength reduction due to self-condensation of the coupling agent.

  Moreover, when coat | covering a carrier core with a coupling agent, 0.001-0.5 mass% is preferable with respect to a carrier core. In this case, the coupling agent includes one or more functional groups selected from an epoxy group, amino group, mercapto group, organic acid group, ester group, ketone group, halogen group, alkyl group and aldehyde group. A coupling agent having, particularly preferably, a silane coupling agent can be used.

  As a more preferable form of the resin carrier, a phenol resin is used as the binder resin of the carrier core, an epoxy group-containing silane coupling agent is used as the surface treatment agent of the inorganic compound particles, and it is contained in the silicone coat resin covering the carrier core. A thing using the silane coupling agent which has an amino group as a thing or a pre-processing material of a carrier core is mentioned. By doing so, the moisture adsorbed moderately in the binder resin causes the silane coupling agent containing amino groups to hydrolyze and self-condensate while hydrogen bonding with the hydroxyl groups of the phenol resin, or Condensation with the remaining silanol groups in the silicone resin to form a strong coating, and at the same time, the amino groups react with the epoxy groups of the surface treatment agent of the inorganic compound particles, improving the adhesion of the silicone resin, missing the coating resin, etc. Is suppressed.

  In order to make the physical properties of the resin carrier fall within a predetermined range, it is preferable to add nonmagnetic inorganic compound particles to the carrier core in addition to the magnetic inorganic compound particles. Adjustment of the specific gravity of the carrier is that the total amount of the magnetic inorganic compound particles and the nonmagnetic inorganic compound particles is 70 to 99% by mass in the magnetic carrier, more preferably 80 to 99% by mass. And the relationship between the adjustment of the particle size distribution of the carrier and the mechanical strength of the carrier core.

  The shape of the resin carrier is appropriately selected so as to be convenient for a predetermined system. However, the resin carrier is more preferably spherical. If the resin carrier is not spherical, the fluidity as a developer will be inferior. If a small amount of developer is used, the ability to impart triboelectric charge to the toner will be reduced and the shape of the magnetic brush will become uneven at the development pole. It becomes difficult to obtain high-quality images.

  Next, the suitable manufacturing method of the resin carrier based on this invention is described.

  The treatment with the lipophilic agent for the inorganic compound particles may be performed by adding and mixing a solution of a coupling agent or an organic compound to the inorganic compound particles.

  The carrier core is a so-called polymerization method in which inorganic compound particles dispersed in a solvent are dispersed in a monomer constituting the binder resin, and an initiator or a catalyst is added, or a binder resin containing inorganic compound particles. The so-called kneading and pulverizing method can be used, but a polymerization method is preferable in order to easily control the particle size of the resin carrier and to obtain a sharp particle size distribution. That is, the carrier core produced by the polymerization method can be arbitrarily controlled by the reaction conditions during the polymerization, for example, the catalyst addition conditions, the polymerization temperature conditions, the stirring conditions of the solvent dispersion, and the like. Unlike the case where it carries out, even if it does not pass through a classification | category process, since a sharp particle size distribution without a fine powder with a fine particle size of 25-55 micrometers can be achieved, it is preferable.

  The production of a carrier core by a polymerization method using a phenol resin as a binder resin preferably used in the present invention is performed, for example, by dispersing inorganic compound particles subjected to lipophilic treatment with phenols and aldehydes in an aqueous medium. And a method in which a basic catalyst is added to cause a polymerization reaction. A method of forming a so-called modified phenol resin in which a natural resin such as rosin and a dry oil such as paulownia oil or linseed oil are mixed and reacted together with phenols can also be mentioned.

  In particular, when the binder resin is a phenol resin, an appropriate amount of adsorbed water is retained, which is preferable in order to promote hydrolysis of the coupling agent and form a strong coating.

  As another condition, the production of a carrier core using an epoxy resin as a binder resin can be carried out by, for example, dispersing bisphenols, epihalohydrin and an oleophilic inorganic compound particle in an aqueous medium and polymerizing in an alkaline aqueous medium. The method of making it react is mentioned.

  Furthermore, as another condition, the manufacture of a carrier core using a melamine resin as a binder resin can be performed by, for example, dispersing melamines and aldehydes in an aqueous medium and inorganic compound particles subjected to lipophilic treatment to form a weakly acidic catalyst. And a polymerization reaction in the presence of.

  Examples of the carrier core manufacturing method using other binder resins include, for example, kneading the oleophilic inorganic compound particles with various resins, pulverizing, classifying as necessary, and further spheroidizing The method of performing a process etc. are mentioned.

  The carrier core composed of the inorganic compound particles and the binder resin that have been subjected to the oleophilic treatment is also subjected to heat treatment as necessary in order to further cure the resin. It is particularly preferable to carry out under reduced pressure or in an inert atmosphere in order to prevent oxidation of inorganic compound particles and the like.

  The coating treatment of the carrier core with the coupling agent is carried out by immersing the carrier core in a solution obtained by dissolving the coupling agent in water or a solvent by a conventional method, followed by filtration and drying, or the coupling agent while stirring the carrier core. A method of spraying and drying an aqueous solution or a solvent solution is used. In particular, in order to prevent the carrier cores from being united and to form a uniform coating layer, a method of treating with stirring is preferred.

  The coating of the resin may be performed by a known method, for example, a method of dry-mixing the carrier core and the resin using a Hellshell mixer or a high-speed mixer, a method of impregnating the carrier core in a solvent containing the resin Any of the methods of spraying resin on the carrier core using a spray dryer may be used.

  In addition, a method in which a carrier core is reacted with phenols, aldehydes, or melamines and aldehydes in an aqueous medium to coat the phenol resin or melamine resin, or a mixture of acrylonitrile and other vinyl monomers in an aqueous medium. A method of coating with acrylonitrile and polymerizing with acrylonitrile, or a method of coating with polyamide resin by anionic polymerization of lactams may be used.

(Measurement method of carrier characteristic value)
Here, a method of measuring characteristic values used for the carrier of the present invention will be described. In addition, it measured similarly also in the Example mentioned later.

  (1) The 50% particle size of the carrier, carrier core, and inorganic compound particles is a value measured by a laser diffraction particle size distribution meter (manufactured by Horiba, Ltd.). A specific measurement method is as follows.

  Using a Microtrac particle size analyzer (manufactured by Nikkiso Co., Ltd.), the carrier and carrier core are measured with a range setting of 7 to 700 μm, and the inorganic compound particles are measured with a range setting of 0.0032 to 6.5406 μm. To obtain a 50% particle size.

(2) Measurement of apparent density: The apparent density is measured using a powder tester (manufactured by Hosokawa Micron). As a measurement, a 100 mesh (mesh 140 μm) sieve is set on a vibration table, and an apparent density measuring cup (internal capacity 100 cc) whose mass has been measured in advance is placed immediately below. Next, the rheostat scale is set to 2.0 and vibration is started. A measurement sample is gently allowed to flow out of the vibrating 100 mesh sieve so as to enter the measurement cup. When the cup is filled with the heaped sample, the vibration is stopped, and the upper surface of the heaped cup is ground with a blade and accurately weighed with a balance. Since the measuring cup has an internal capacity of 100 cc, the apparent density (g / cm ³ ) = the mass of the sample ÷ 100. The sample used was left for about 12 hours in an environment of 23 ° C. and 60% RH, and the measurement environment was 23 ° C. and 60% RH.

  When measuring the carrier physical properties from the developer, the developer is washed with ion exchange water containing 1% of Contaminone N (surfactant) to separate the magnetic toner and the carrier, and then the above measurement is performed.

  Next, preferred embodiments of the magnetic toner used in the developer of the present invention will be described.

  The magnetic toner according to the present invention preferably has a weight average particle size of 3.0 to 10.0 [mu] m, particularly preferably 4.0 to 9.0 [mu] m.

  When the weight average particle diameter (D4) of the magnetic toner exceeds 10.0 μm, the magnetic toner particles for developing the electrostatic latent image become large. Therefore, even if the magnetic force of the carrier is lowered, the development is faithful to the electrostatic latent image. In addition, magnetic toner tends to scatter when electrostatic transfer is performed. In addition, the magnetic toner having a weight average particle size of less than 3.0 μm is not easy to handle as a powder, and at the same time, the miscibility with the carrier is not uniform, and the magnetic toner cannot be charged well. The distribution becomes wide, and problems such as poor charging (reversal component generation) and uneven particle size distribution of the developed magnetic toner are likely to occur.

  As the binder resin used in the magnetic toner, the following binder resins can be used.

  For example, styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and homopolymers of substituted styrene; 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, styrene-vinyl methyl ether copolymer, styrene-vinyl Styrene copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride; phenol Resin; Naturally modified Natural resin modified maleic acid resin; acrylic resin; methacrylic resin; polyvinyl acetate; silicone resin; polyester resin; polyurethane; polyamide resin; furan resin; Petroleum-based resins can be used. Preferable binder resins include styrene copolymers or polyester resins. A cross-linked styrene resin is also a preferable binder resin.

  The styrenic polymer or styrenic copolymer may be cross-linked, or may be a mixed resin of a cross-linked resin and a non-cross-linked resin.

  As the crosslinking agent for the binder resin, a compound having two or more polymerizable double bonds may be mainly 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 compounds such as divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups. These are used alone or as a mixture.

  As addition amount of a crosslinking agent, 0.001-10 mass parts is preferable with respect to 100 mass parts of polymerizable monomers.

  The magnetic toner may contain a charge control agent.

  There are the following substances that control the magnetic toner to be negatively charged. For example, organometallic compounds and chelate compounds are effective, and monoazo metal compounds, acetylacetone metal compounds, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal compounds are preferably used. Further, aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, their anhydrides, their esters, their phenol derivatives such as bisphenol; urea derivatives; metal-containing salicylic acid compounds; Metallic naphthoic acid compounds; boron compounds; quaternary ammonium salts; calixarene; silicon compounds; styrene-acrylic acid copolymers; styrene-methacrylic acid copolymers; styrene-acrylic-sulfonic acid copolymers; and nonmetal carboxylic acid systems Compounds.

  There are the following substances that control the magnetic toner to be positively charged. Modified products with nigrosine and fatty acid metal salts, quaternary ammonium salts such as guanidine compounds, imidazole compounds, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs thereof Some onium salts such as phosphonium salts and their lake pigments, triphenylmethane dyes and these lake pigments (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid) Acids, ferricyanides, ferrocyanides, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, Octyl tin borate, diorgano tin borate such as dicyclohexyl tin borate; can be used in combination singly, or two or more kinds. Among these, a charge control agent such as a nigrosine-type quaternary ammonium salt is particularly preferably used.

  These charge control agents are used in an amount of 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.2 to 4 parts by weight, based on 100 parts by weight of the resin component of the magnetic toner. good.

  The magnetic toner used in the present invention may be other colorant, in addition to the magnetic material, and carbon black, yellow / magenta / cyan colorant as a black colorant, and a black toner.

The saturation magnetization of the magnetic toner used in the present invention is 1.0 to 35.0 Am ² / kg, preferably 5.0 to 25.0 Am ² / kg. Therefore, it is preferable that the magnetic toner particles contain 1 to 50% by mass, preferably 3 to 30% by mass of a magnetic material. When the saturation magnetization of the magnetic toner is less than 1.0 Am ² / kg, the effect of suppressing the scattering of the magnetic toner is small, and when it exceeds 35.0 Am ² / kg, the difference in magnetic properties with the carrier is small, and carrier adhesion is likely to occur. As a result, it is difficult to keep the carrier amount constant, it becomes difficult to control the magnetic toner density, and the change in image density tends to be large. Preferably, by setting the weight average particle diameter of the magnetic toner to 4.0 to 9.0 μm and 5.0 to 25.0 Am ² / kg, the magnetic toner has excellent fluidity and uniform image density unevenness. An image can be obtained, the transferability is further improved, and the cleaning life of the cleaning member and the photosensitive member can be extended without causing the magnetic toner to be poorly cleaned.

  Examples of magnetic materials used in the present invention include iron oxides such as magnetite, hematite, and ferrite; metals such as iron, cobalt, and nickel; these metals and aluminum, cobalt copper, lead, magnesium, tin, zinc, and antimony. , Alloys with metals such as beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium and mixtures thereof.

  Further, when the black toner of the present invention is obtained by the method for producing a polymerized toner, it is preferable to surface-modify the composite particles with a surface modifier that does not inhibit polymerization of the polymerizable monomer. Examples of the modifier include a silane coupling agent and a titanium coupling agent.

The amount of the magnetic material contained in the magnetic toner preferably used in the present invention is preferably 10 to 200 parts by mass, more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the resin component. The magnetic material has a magnetic property of 795.8 kA / m (10 K oersted) applied, a coercive force (Hc) of 1.6 to 24 kA / m (20 to 300 oersted), a saturation magnetization (σs) of 50 to ²⁰⁰ Am ² / kg, It is preferable to have a residual magnetization (σr) of ^{2 to} 20 Am ² / kg.

  In the present invention, it is particularly preferable to use magnetic carbon black composite particles in which magnetic fine particles are trapped inside the structure of carbon black particles and stably fixed as a colorant for the toner. Even when used as a colorant, a black toner having stable magnetic properties and chargeability can be obtained. Furthermore, the blackness and magnetic properties of the resulting black toner can be arbitrarily controlled by appropriately combining the particle size of the carbon black to be combined or the type of magnetic fine particles.

  The magnetic carbon black composite particles used as the toner colorant in the present invention are produced as follows. That is, in the combustion chamber of the reactor head, fuel is burned to form a high-temperature combustion gas stream, and carbon black is generated by introducing a hydrocarbon raw material into the high-temperature combustion gas stream and causing a thermal decomposition reaction. Then, in the carbon black production method in which water is sprayed into the carbon black-containing high-temperature gas stream and cooled, and then the carbon black is separated and collected, hydrocarbons are obtained from two positions, upstream and downstream, of the high-temperature combustion gas stream. The composite particles consisting of carbon black and magnetic metal fine particles are non-oxidized by spraying the magnetic transition metal compound from the intermediate position between the upstream position and downstream position where the raw material is sprayed and the hydrocarbon raw material is sprayed. By heating to 400 to 900 ° C. in a neutral atmosphere, magnetic carbon black composite particles used as a toner colorant in the present invention can be obtained. It is.

  In the above composite particles, the magnetic metal fine particles are dispersed microscopically in the primary particles of carbon black and fixed by fusion, and the carbon black secondary particles (aggregates) are coated while covering the surface layer of the mixed fine particles. As a result, the magnetic metal fine particles are stably fixed and integrated in the carbon black secondary particles. In this case, the chemical composition of the fine metal particles often exists in the form of various oxides, and some of them are compounded in the state of reduced metal. These composite particles preferably have an average particle size of 2 μm or less, more preferably about 0.02 to 0.5 μm.

  The magnetic carbon black composite particles obtained as described above preferably contain 10 to 180 nm magnetic fine particles. When the particle size of the magnetic fine particles is less than the above range, the color tone of the toner is reddish. On the other hand, when the particle size of the magnetic fine particles exceeds the above range, it is not preferable in that it is difficult to fix the particles uniformly in the carbon black. A more preferable range of the particle diameter of the magnetic fine particles is 15 to 100 nm, and a black toner having excellent blackness and magnetic characteristics can be obtained particularly within this range.

  The quantitative relationship between the magnetic fine particles and carbon black is preferably in the range of 2 to 100 parts by weight, preferably 10 to 100 parts by weight of the magnetic fine particles with respect to 100 parts by weight of carbon black. If the amount of the magnetic fine particles is less than the above range, it is not preferable in that the magnetic properties are lowered, and particularly the productivity at the time of classification is reduced. On the other hand, if the amount of the magnetic fine particles exceeds the above range, carbon cracks are not preferable. It is not preferable in that it is difficult to be fixed inside. A black toner having excellent blackness and magnetic properties in the above range can be obtained.

  Next, a method for producing the magnetic toner used in the present invention will be described. The magnetic toner used in the present invention can be produced using a pulverization method and a polymerization method.

  As a method for producing the polymerization method, there are disclosed a method for obtaining a spherical toner by atomizing a molten mixture in air using a disk or other fluid nozzle described in JP-B-56-13945, JP-B-36-10231, JP A method of directly producing toner using the suspension polymerization method described in JP-A-59-53856 and JP-A-59-61842, or a monomer that is soluble and insoluble in a monomer. An emulsion polymerization method represented by a dispersion polymerization method that directly produces a toner using an aqueous organic solvent or a soap-free polymerization method that produces a toner by directly polymerizing in the presence of a water-soluble polar polymerization initiator, After the production, the toner can be produced using a hetero-aggregation method in which polar particles having opposite charges are added and associated.

  Among these, polymerized toner particles obtained by a method of directly polymerizing a monomer composition containing at least a polymerizable monomer, a colorant and a wax to produce toner particles are preferable.

  A suitable inorganic compound or organic compound stabilizer is used for the dispersion medium used in the production of the polymerization method toner by emulsion polymerization, dispersion polymerization, suspension polymerization, seed polymerization, or polymerization method using hetero-aggregation method. It is preferable to do. Examples of inorganic compound stabilizers include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, Examples thereof include calcium sulfate, barium sulfate, bentonite, silica, and alumina. As stabilizers for organic compounds, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, polyacrylic acid and its salts, starch, polyacrylamide, polyethylene oxide, poly (hydroxystearic acid) -G-methyl methacrylate-eu-methacrylic acid) copolymers and nonionic or ionic surfactants.

  When the emulsion polymerization method and the heteroaggregation method are used, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant and a nonionic surfactant are used. These stabilizers are preferably used in an amount of 0.2 to 30 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Among these stabilizers, when an inorganic compound is used, a commercially available one may be used as it is, but in order to obtain fine particles, the inorganic compound may be produced in a dispersion medium.

  For fine dispersion of these stabilizers, 0001 to 0.1 parts by mass of a surfactant may be used with respect to 100 parts by mass of the polymerizable monomer. This surfactant is for promoting the stabilizing action of the dispersion stabilizer. Specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate and the like.

  In the present invention, as the colorant used in the polymerization toner, it is necessary to pay attention to the polymerization inhibitory property and water phase transferability of the colorant. It is better to apply the process. In particular, dyes and carbon blacks have a polymerization inhibition property, so care must be taken when using them. A preferable method for surface-treating the dye system includes a method in which a polymerizable monomer is previously polymerized in the presence of these dyes, and the obtained colored polymer is added to the monomer system. Carbon black may be treated with a material that reacts with the surface functional groups of carbon black, such as polyorganosiloxane, in addition to the same treatment as the above dye.

  Next, the external additive externally added to the magnetic toner particles will be described.

  In the magnetic toner used in the present invention, inorganic fine particles such as silica, alumina and titanium oxide; fine particles of organic fine particles such as polytetrafluoroethylene, polyvinylidene fluoride, polymethyl methacrylate, polystyrene and silicone are externally added. It is preferable that By externally adding the above-mentioned fine powder to the magnetic toner particles, the fine powder exists between the magnetic toner and the carrier, or between the magnetic toner particles, and the fluidity of the developer is improved. The service life is also improved. The average particle size of the fine powder is preferably 0.2 μm or less. When the number average particle diameter exceeds 0.2 μm, the effect of improving the fluidity is reduced, and the image quality may be deteriorated due to defects during development and transfer. The measurement of the number average particle diameter of these fine powders will be described later.

The surface area of these fine powders, the specific surface area by nitrogen adsorption 30 m ² / g or more measured by a BET method, is good especially in the range of 5~400m ² / g. The addition amount of the fine powder is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the toner particles.

  Among them, it is preferable from the viewpoint of charging property to use at least one kind of hydrophobized silica. In other words, since silica has higher chargeability than a fluidizing agent such as alumina or titanium oxide, the adhesion to the magnetic toner particles is high, and the free external additive is reduced. Therefore, filming on the electrostatic latent image carrier and contamination of the charging member can be suppressed. However, when the charging property is increased, the external additive partially released tends to move to the carrier. Even in that case, the polymerization method carrier of the present invention can suppress adhesion of the fluidizing agent because of its surface shape.

  In addition, the inorganic fine particles are preferably subjected to a hydrophobic treatment in order to maintain chargeability under high humidity. An example of the hydrophobic treatment is shown below.

  A silane coupling agent is mentioned as one of the hydrophobizing agents, and the amount thereof is 1 to 40 parts by mass, preferably 2 to 35 parts by mass with respect to 100 parts by mass of the inorganic fine particles. When the amount is 1 to 40 parts by mass, moisture resistance is improved and aggregates are hardly generated.

As a silane coupling agent used for this invention, what is shown by following General formula (3) is mentioned.
RmSiYn Formula (3)
[In the formula, R represents an alkoxy group or a chlorine atom, m is an integer of 1 to 3, Y represents a hydrocarbon group (for example, an alkyl group, a vinyl group, a glycidoxy group, a methacryl group), n is an integer of 3-1. ]

  Specifically, for example, dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, Examples thereof include vinyltriacetoxysilane, divinylchlorosilane, dimethylvinylcholorsilane and the like.

  The silane coupling agent treatment of the inorganic fine particles is a dry treatment in which the vaporized silane coupling agent is reacted with the inorganic fine particles made into a cloud by stirring, or the inorganic fine particles are dispersed in a solvent and the silane coupling agent is dropped. The treatment can be performed by a generally known method such as a wet method for reacting. The above hydrophobization treatment can be used in combination as appropriate.

  Another example of the hydrophobizing agent is silicone oil.

As a preferable silicone oil, those having a viscosity at 25 ° C. of 5 to 2000 mm ² / s are preferably used. A silicone oil having a low molecular weight and a low viscosity is not preferable because volatile matter may be generated by heat treatment, while a silicone oil having a high molecular weight and a high viscosity is difficult to perform a surface treatment operation. As the silicone oil, methyl silicone oil, dimethyl silicone oil, phenylmethyl silicone oil, chlorophenyl methyl silicone oil, alkyl-modified silicone oil, fatty acid-modified silicone oil, and polyoxyalkyl-modified silicone oil are preferable.

  The above-mentioned silicone oil is preferably used having the same polarity as that of the magnetic toner particles in order to improve the chargeability of the magnetic toner.

  A known technique is used as a method of treating the inorganic fine particles with silicone oil. For example, inorganic fine particles and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or a method of spraying silicone oil onto inorganic fine particles may be used. Alternatively, it may be prepared by dissolving or dispersing silicone oil in a suitable solvent, mixing with inorganic fine particles, and then removing the solvent.

  The silicone oil is used in an amount of 1.5 to 60 parts by mass, preferably 3.5 to 40 parts by mass, with respect to 100 parts by mass of the inorganic fine particles to be treated. When the amount is 1.5 to 60 parts by mass, the surface treatment with silicone oil can be performed uniformly, and filming and voids can be suitably prevented, and the toner chargeability is prevented from deteriorating due to moisture absorption under high humidity, and durable. It is possible to prevent a decrease in image density.

  The additive for the purpose of imparting various magnetic toner characteristics preferably has an average particle diameter of 0.005 to 0.2 μm from the viewpoint of durability in the magnetic toner or when added to the magnetic toner. The average particle size of the additive means the number average particle size obtained by observing the surface of the magnetic toner particles with an electron microscope. As additives for the purpose of imparting these characteristics, for example, the following are used.

  In addition to the inorganic fine particles and organic fine particles described above, other fluidity imparting agents include metal oxides such as silicon oxide, aluminum oxide, and titanium oxide; carbon black; and carbon fluoride. Each of these is more preferably subjected to a hydrophobic treatment.

  Examples of the abrasive include metal oxides such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide and chromium oxide; nitrides such as silicon nitride; carbides such as silicon carbide; and calcium sulfate, barium sulfate and carbonic acid. Examples include metal salts such as calcium.

  Examples of the lubricant include fluorine resin powders such as vinylidene fluoride and polytetrafluoroethylene; and fatty acid metal salts such as zinc stearate and calcium stearate.

  Examples of the charge controllable particles or conductivity imparting particles include metal oxides such as tin oxide, titanium oxide, zinc oxide, silicon oxide and aluminum oxide; and carbon black.

  These additives are preferably used in an amount of 0.1 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the magnetic toner particles. These additives may be used alone or in combination.

  The developer used in the present invention is used as a two-component developer by mixing the above-described magnetic carrier and magnetic toner.

  When a two-component developer is prepared by mixing a magnetic toner and a magnetic carrier, the mixing ratio is 3 to 30% by mass, preferably 4 to 20% by mass, as the toner concentration in the developer. Is obtained. If the toner concentration is less than 3% by mass, the image density tends to be low, and if it exceeds 30% by mass, fog and image density unevenness are likely to occur, and the useful life of the developer is likely to be reduced.

  The ratio (A / B) of the weight average particle diameter (A) of the magnetic toner to the 50% particle diameter (B) of the magnetic carrier is preferably 0.1 to 0.3. If it is less than 0.1, it becomes difficult to charge the magnetic toner satisfactorily, and fog and image density unevenness are likely to occur. On the other hand, if it exceeds 0.3, the charge amount of the magnetic toner, especially under low humidity, becomes too high, the self-control stability of the magnetic toner concentration is lowered, the fluctuation of the image density is likely to increase, and the fog is likely to occur. .

  A specific example of the measurement of magnetic toner is shown below.

Measurement Method of Saturation Magnetization of Magnetic Toner Saturation magnetization of toner was measured using an oscillating magnetic field type magnetic property automatic recording apparatus BHV-35 manufactured by Riken Denshi Co., Ltd. As measurement conditions, an external magnetic field of 3000 / 4π (kA / m) was created as the magnetic characteristics, and the strength of magnetization at that time was determined. Produced in a state where the toner is packed in a cylindrical plastic container so that the particles do not move sufficiently, measure the magnetization moment in this state, measure the actual mass when the sample is put, The strength of magnetization (Am ² / kg) was determined.

Measurement method of average particle size and particle size distribution of magnetic toner 0.1 to 5 ml of a surfactant (alkylbenzene sulfonate) is attached to 100 to 150 ml of an electrolyte solution, and 2 to 20 mg of a measurement sample is added thereto. The electrolytic solution in which the sample is suspended is dispersed for 1 to 3 minutes with an ultrasonic disperser, and the aperture is adjusted to a toner size appropriately between 17 μm and 100 μm using the Coulter counter multisizer described above, and the volume is 0 based on the volume. Measure the particle size distribution of 3 to 40 μm. The number average particle diameter and weight average particle diameter measured under these conditions were determined by computer processing.

  By using the two-component developer of the present invention, the share of the developer in the developing device is small, and an image without image quality deterioration can be achieved even when a large number of copies are made.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to these.

<1> Manufacture of magnetic carrier <Manufacture of magnetic carrier 1>
-5 parts by mass of phenol (hydroxybenzene)-8 parts by mass of a formalin aqueous solution of 37% by mass-5 parts by mass of water-Silane coupling agent (KBM403: 56 parts by mass of magnetite fine particles surface-treated by Shin-Etsu Chemical Co., Ltd. (50% particle size 0.22 μm)
-Α-Fe ₂ O ₃ fine particles surface-treated with a silane coupling agent (KBM403 manufactured by Shin-Etsu Chemical Co., Ltd.) 24 parts by mass (50% particle size 0.30 μm)
-25 mass% ammonia water 1 mass part The said material was put into the four necked flask, and it heated up and maintained to 84 degreeC in 60 minutes, stirring and mixing, and it was made to react and harden for 120 minutes. After cooling to 25 ° C. and adding 50 parts by mass of water, the supernatant was removed, the precipitate was washed with water and air-dried. Next, this was dried under reduced pressure (665 Pa = 5 mmHg) at 180 ° C. for 28 hours to obtain a magnetic carrier core (A) having a phenol resin as a binder resin.

  A 5 mass% methanol solution of a silane coupling agent (KBM903, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of the obtained magnetic carrier core (A).

  During coating, methanol was volatilized while coating while applying a shear stress to the magnetic carrier core (A) continuously.

  While stirring the magnetic carrier core (A) treated with the silane coupling agent in the above processing machine at 70 ° C., the silicone resin SR2411 (manufactured by Toray Dow Corning Co., Ltd.) becomes 5% as the silicone resin solid content. After diluting with toluene, it was added under reduced pressure to perform 0.8 mass% resin coating.

  Thereafter, the toluene was volatilized while being stirred for 2 hours in an atmosphere of nitrogen gas, and then heat treatment was performed at 160 ° C. for 1 hour in an atmosphere of nitrogen gas to loosen the agglomerates, and then 200 mesh ( Coarse particles of 75 μm or more were removed to obtain a magnetic carrier 1.

The resin content of the obtained magnetic carrier 1 is 11% by mass, the 50% particle size is 33 μm, 21 μm or less is 0.3% by volume, 72 μm or more is 0.2% by volume, and the apparent density is 1.83 g / cm ^3. Met.

<Manufacture of magnetic carriers 2 and 3>
In the production example of the magnetic carrier 1, by changing the individual liquid ratio, the resin content is 11% by mass, the 50% particle size is 18 μm, 21 μm or less is 75.5% by volume, 72 μm or more is 0% by volume, apparent density Is 1.80 g / cm ³ of magnetic carrier 2, the resin content is 11% by mass, the 50% particle size is 82 μm, 21 μm or less is 0% by volume, 72 μm or more is 72.8% by volume, and the apparent density is 1 A magnetic carrier 3 of .85 g / cm ³ was obtained.

<Manufacture of magnetic carrier 4>
Ferrite component (Fe ₂ O ₃ : 55.8 mol%, MgO: 22.5 mol%, MnO: 20.2 mol%, SrO: 1.5 mol%)
The ferrite raw material oxide blended in the above composition was wet mixed in a ball mill, dried and pulverized, then calcined at 750 ° C. for 2 hours, and pulverized to a crusher of about 0.1 to 1.0 mm. Furthermore, wet milling with a ball mill to make a slurry, adding 1.0% of polyvinyl alcohol as a binder and 4% of CaCO ₃ as a pore adjusting agent, granulating into spherical particles by a spray dryer method, oxygen gas concentration 0.5 Sintered at 990 ° C. in a nitrogen gas atmosphere and sieved with a sieve having an opening of 200 μm to remove coarse particles, and then classified with an air classifier (Elbow Jet Lab EJ-L3, manufactured by Nippon Steel Mining Co., Ltd.). Then, the particle size was adjusted to obtain core particles.

next,
Toluene and methyl ethyl ketone (4: 1) mixed solvent 1000 parts by mass Styrene / methyl methacrylate copolymer (4: 6, Mw = 50,000) 80 parts by mass Methyl methacrylate / perfluoropropylethyl methacrylate copolymer (80:20, Mw) = 18,000) 20 parts by mass The above components were mixed to prepare a coating liquid. Next, the composition of the solution is adjusted with respect to the core material particles so that the solid content of the coating resin is 10% by mass, the solvent is removed by drying under reduced pressure while stirring and mixing with a vacuum kneader, and baking is performed at 130 ° C for 2 hours And the resin content is 9% by mass, the 50% particle size is 35 μm, 21 μm or less is 3.8% by volume, 72 μm or more is 1.3% by volume, and the apparent density is 1. A magnetic carrier 4 of .87 g / cm ³ was obtained.

<Manufacture of magnetic carriers 5 and 6>
In Production Example 4, the ferrite component was changed (Fe ₂ O ₃ : 55.8 mol%, MgO: 22.5 mol%, Li ₂ O: 12.2 mol%, BeO: 9.5 mol%) The 50% particle size is 36 μm, and the resin content is 4 mass except that the porosity adjusting agent is changed to 2% and 7% CaCO ₃ and the solid content of the coating resin is 4 mass% and 35 mass%. %, 21 μm or less is 2.6% by volume, 72 μm or more is 1.2% by volume, the magnetic carrier 5 has an apparent density of 2.4 g / cm ³ , and the resin content is 26% by mass, and the 50% particle size is 37 μm. Thus, a magnetic carrier 6 having a volume of 21 μm or less at 5.3 volume%, 72 μm or more at 2.9 volume%, and an apparent density of 1.1 g / cm ³ was obtained.

<Manufacture of magnetic carrier 7>
Ferrite component (Fe ₂ O ₃ : 58 mol%, NiO: 21.0 mol%, ZnO: 21.0 mol%)
The magnetic carrier 7 having a 50% particle size of 36 μm, 21 μm or less is 2.4% by volume, 72 μm or more is 2.9% by volume, and the apparent density is 2.2 g / cm ³ , except for changing to Got.

<1> Manufacture of magnetic toner <Manufacture of magnetic toner 1>
(Example of production of magnetic carbon black composite particles)
An air introduction duct and a fuel burner are attached to the furnace head of a cylindrical reflection furnace having a diameter of 80 mm and a length of 2500 mm, and a raw material spray introduction nozzle and a magnetic transition metal are positioned 200 to 800 mm downstream from the furnace head. Each compound injection injection nozzle was inserted in the furnace axial direction.

Using this reactor, propane gas supply rate (0.5 m ³ / h), combustion air amount (12.5 m ² / h), hydrocarbon feed upstream pentanol (107 g / h), downstream benzene (250 g / h) h) Magnetic carbon black composite particles 1 were produced under the conditions of an iron chloride solution (ethanol 10%) (440 g / h) and an atomization gas of 1.0 m ² / h (μ ² ). The characteristics of this magnetic carbon black composite particle are:
Carbon black particle diameter (b): 20.0 nm
Magnetic fine particle diameter (a): 16.0 nm
Magnetic fine particle content: 50%
Composite particle size: 50 nm

To 710 parts by mass of ion-exchanged water, 450 parts by mass of 0.1 M Na ₃ PO ₄ aqueous solution was added and heated to 60 ° C., and then at 14000 rpm using a TK homomixer (made by Tokushu Kika Kogyo). Stir. To this, 68 parts by mass of 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium having a pH of 5.8 containing a calcium phosphate compound.

-Styrene 160 parts by mass-n-butyl acrylate 34 parts by mass-Magnetic carbon black composite particles produced by the above production example 40 parts by mass-Zirconium di-t-butylsalicylate compound 0.8 parts by mass-Polyester resin 10 parts by mass ( A condensate of propylene oxide modified bisphenol A and isophthalic acid,
Tg = 65 ° C., Mw = 11000, Mn = 6000)
-Stearyl stearate wax (DSC main peak 60 ° C) 30 parts by mass The above materials were heated to 60 ° C, and uniformly dissolved and dispersed at 13000 rpm using a TK homomixer (manufactured by Special Machine Industries). . In this, 10 g of polymerization initiators 2,2′-azobis (2,4-dimethylvaleronitrile) were dissolved to prepare a polymerizable monomer composition.

The polymerizable monomer composition was charged into the aqueous medium, and stirred at 10,000 rpm for 10 minutes in a Claire mixer (manufactured by MTechnic Co., Ltd.) at 65 ° C. and N ₂ atmosphere. Granulated. Thereafter, while stirring the aqueous medium with a paddle stirring blade, the temperature was raised to 80 ° C., and the polymerization reaction was carried out for 8 hours while maintaining the pH at 6.

  After the completion of the polymerization reaction, the mixture was cooled and hydrochloric acid was added to adjust the pH to 1.5 to dissolve calcium phosphate, followed by filtration, washing with water, drying, and classification to obtain polymer particles (toner particles 1).

The following two types of external additives are externally added to 100 parts by mass of the resulting polymer particles (toner particles 1), and after the external addition, coarse particles are removed with a 300 mesh (aperture 53 μm) sieve, and negatively charged. Magnetic toner 1 was obtained. The magnetic toner 1 had a weight average particle diameter of 7.1 μm and a saturation magnetization of 5.4 Am ² / kg.

(1) First external additive (0.7 parts by mass of hydrophobic silica fine powder)
Hydrophobized with 10 parts by mass of hexamethyldisilazane in a gas phase with respect to 100 parts by mass of silica fine powder, the BET specific surface area is 38 m ² / g, and the number average particle diameter is 30 nm.

(2) Second external additive (0.5 parts by mass of hydrophobic titanium oxide fine powder)
Hydrophobized with 10 parts by mass of n-octyltrimethoxysilane in an aqueous medium to 100 parts by mass of fine titanium oxide powder, BET specific surface area is 95 m ² / g, and number average particle diameter is 40 nm. .

<Manufacture of magnetic toner 2>
In the same manner as in Example 1, except that 80 parts by mass of magnetite fine particles (KBM403, Shin-Etsu Chemical Co., Ltd. surface-treated magnetite fine particles) (50% particle size 0.18 μm) were used. The magnetic toner 2 had a weight average particle diameter of 7.5 μm and a saturation magnetization of 18.9 Am ² / kg.

<Manufacture of magnetic toner 3>
In Example 1, instead of using magnetic carbon black composite particles, 240 parts by mass of a silane coupling agent (KBM403, Shin-Etsu Chemical Co., Ltd. surface-treated magnetite fine particles (50% particle size 0.18 μm)) was used. Obtained magnetic toner 3. The magnetic toner 3 had a weight average particle diameter of 7.5 μm and a saturation magnetization of 37.5 Am ² / kg.

<Manufacture of magnetic toner 4>
In Example 2, magnetic toner 4 was obtained in the same manner except that 160 parts by mass of magnetite was used. The magnetic toner 3 had a weight average particle diameter of 7.5 μm and a saturation magnetization of 30.0 Am ² / kg.

<Manufacture of magnetic toner 5>
A magnetic toner 5 was obtained in the same manner as in Example 1 except that 40 parts by mass of magnetic carbon black composite particles produced so that the magnetic fine particle content was 10% was used. The magnetic toner 5 had a weight average particle diameter of 7.7 μm and a saturation magnetization of 0.8 Am ² / kg.

<Manufacture of magnetic toner 6>
・ Terephthalic acid / fumaric acid / trimellitic anhydride /
100 parts by mass of a polyester resin comprising a derivative of bisphenol A (Tg 62 ° C., Mw = 20000, Mn = 8000)
・ 40 parts by mass of magnetite fine particles (50% particle size 0.18 μm)
1 part by weight of a zirconium compound of di-t-butylsalicylic acid 5 parts by weight of paraffin wax (DSC main peak 60 ° C.) The above materials are sufficiently premixed with a Henschel mixer and melt-kneaded with a twin-screw extrusion kneader. After cooling, it was coarsely pulverized to about 1 to 2 mm using a hammer mill, and then finely pulverized with an air jet type fine pulverizer. Further, the obtained finely pulverized product was classified and then subjected to spheronization treatment to obtain negative triboelectrically chargeable magnetic toner particles 6 having a weight average particle diameter of 7.8 μm.

Two external additives were externally added to the obtained toner particles in the same manner as in the production of the toner 1 to prepare a negatively chargeable magnetic toner 6. The magnetic toner 6 had a weight average particle diameter of 7.8 μm and a saturation magnetization of 20.5 Am ² / kg.

<Manufacture of magnetic toner 7>
(Toner binder synthesis)
Into a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 724 parts by mass of bisphenol A ethylene oxide 2-mole adduct, 276 parts by mass of isophthalic acid and 2 parts by mass of dibutyltin oxide were placed at 230 ° C., 8 at normal pressure. After reacting for 5 hours, the reaction was allowed to proceed under reduced pressure of 10 to 15 mmHg for 5 hours. This was cooled to 160 ° C., 32 parts by mass of phthalic anhydride was added and reacted for 2 hours. Furthermore, this was cooled to 80 ° C. and reacted with 188 parts by mass of isophorone diisocyanate in ethyl acetate for 2 hours to obtain an isocyanate-containing prepolymer (1). Next, 267 parts by mass of this prepolymer (1) and 14 parts of isophoronediamine were reacted at 50 ° C. for 2 hours to obtain a urea-modified polyester (1) having a weight average molecular weight of 64,000.

  In the same manner as above, 724 parts by mass of bisphenol A ethylene oxide 2 mol adduct and 276 parts by mass of terephthalic acid were subjected to polycondensation at 230 ° C. for 8 hours under normal pressure, and then reacted for 5 hours at a reduced pressure of 10 to 15 mmHg to obtain a peak molecular weight of 5000 A polyester (a) which was not modified was obtained.

  200 parts by mass of urea-modified polyester (1) and 800 parts by mass of unmodified polyester (a) are dissolved and mixed in 2000 parts by mass of an ethyl acetate / ethyl methyl ketone (MEK) (1/1) mixed solvent, and a toner binder ( An ethyl acetate / MEK solution of 1) was obtained. Part of the mixture was dried under reduced pressure to isolate toner binder (1). Tg was 62 ° C.

(Production of toner)
In a beaker, 240 parts by mass of the ethyl acetate / MEK solution of the toner binder (1), 20 parts by mass of pentaerythritol tetrabehenate (melting point 81 ° C., melt viscosity 25 cps), and 40 magnetic carbon black composite particles of Example 1 were used. Part by mass and 1 part by mass of a zirconium compound of ditertiary salicylic acid were added, and the mixture was stirred and dissolved uniformly at 60 ° C. and 12000 rpm with a TK homomixer. In a beaker, 706 parts by mass of ion-exchanged water, 294 parts by mass of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 parts by mass of sodium dodecylbenzenesulfonate were uniformly dissolved. Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer. Next, this mixed solution was transferred to a Kolben equipped with a stir bar and a thermometer, heated to 98 ° C. to remove the solvent, filtered, washed, dried, air classified, and the volume average particle size was 7.6 μm. A colored powder was obtained.

Two external additives were externally added to the obtained toner particles in the same manner as in the production of the toner 1 to prepare a negatively chargeable magnetic toner 7. The magnetic toner 7 had a weight average particle diameter of 7.6 μm and a saturation magnetization of 4.1 Am ² / kg.

<Manufacture of magnetic toner 8>
(Preparation of acidic polar group-containing polymerization resin)
Styrene monomer (St) 82 parts by weight butyl acrylate (BA) 18 parts by weight acrylic acid (AA) 4 parts by weight or more of monomer mixture 100 parts by weight of Emulgen 950 1 part by weight (manufactured by Kao Corporation)
2 parts by mass of Neogen R (Daiichi Kogyo Seiyaku Co., Ltd.)
Of potassium persulfate as a catalyst and polymerized at 70 ° C. for 8 hours with stirring to obtain an acidic polar group-containing resin emulsion having a solid content of 50%.

(Preparation of magnetic toner)
Acidic polar group-containing resin emulsion 200 parts by mass Magnetic carbon black composite particles of Example 1 80 parts by mass Polyethylene wax dispersion 20 parts by mass (Chemical WF-640 manufactured by Mitsui Petrochemical Co., Ltd.)
Zirconium compound of ditertiary butylsalicylic acid 2 parts by mass Water 350 parts by mass The above mixture was heated to 25 ° C. with stirring using a disper. The dispersion was then stirred for about 2 hours and then heated to 60 ° C., which was adjusted to pH 8.0 with ammonia. Furthermore, when this dispersion was heated to 90 ° C. and kept at this temperature for 5 hours, particles of about 7.8 μm were obtained. The particle dispersion was cooled, separated, washed with water, and dried. When this particle was observed with a scanning electron microscope, it was observed that it was composed of secondary particles of polymer particles and magnetic fine particles.

Two external additives were externally added to the obtained toner particles in the same manner as in the production of the toner 1 to prepare a negatively chargeable magnetic toner 8. The magnetic toner 8 had a weight average particle diameter of 7.8 μm and a saturation magnetization of 6.0 Am ² / kg.

[Example 1]
The carrier 1 (92 parts by mass) obtained above and the magnetic toner 1 (8 parts by mass) were mixed with a V-type mixer to obtain a starting developer 1.

  Next, the developing device of the Bk station of a commercially available color copying machine CP2150 (manufactured by Canon) was modified as shown in FIG.

  Using an original document with an image area of 5%, using a PBSK paper (manufactured by Canon Sales Co., Ltd.) in an environment of 23 ° C./60%, a 50,000 sheet passing test was performed while supplying magnetic toner 1. Evaluation was performed based on the following evaluation method.

  The results are shown in Table 1. As can be seen from Table 1, good results were obtained.

[Evaluation methods and standards]
(1) Image Density Image density was formed on PBSK paper at an original image density of 1.5 using a Macbeth Densitometer RD918 type (Macbeth Densitometer RD918manufactured by Mcbeth Co.) equipped with an SPI filter. It was measured as the relative density of the average of 5 points at the 4 corners and the center of the image.
A: 1.40 to 1.60
○: Less than 1.30 to 1.45, more than 1.60 to 1.65
Δ: 1.20 to less than 1.35, more than 1.65 to 1.70
X: Less than 1.20, more than 1.70

(2) Halftone reproducibility Using the original image density of 0.3, the relative density was measured in the same manner as in (1).
A: 0.3 to 0.4
○: 0.25 to less than 0.3, more than 0.4 to 0.45
Δ: 0.20 to less than 0.25, more than 0.45 to 0.5
X: Less than 0.2, more than 0.5

(3) Fog The average reflectance Dr (%) of PBSK paper before image printing was measured with a reflectometer ("REFLECTOMETER MODEL TC-6DS" manufactured by Tokyo Denshoku Co., Ltd.). On the other hand, a solid white image was drawn on PBSK paper, and then the reflectance Ds (%) of the solid white image was measured. The fog (%) is calculated from the following formula.
Fog (%) = Dr (%) − Ds (%)
A: Less than 0.4% B: Less than 0.4-0.8% Δ: Less than 0.8-1.2% x: 1.2% or more

(4) Solid Uniformity Using the original image density of 1.5, the relative density of 5 points was measured in the same manner as in (1) and measured as the maximum density difference.
A: 0.0 to less than 0.05 B: 0.05 to less than 0.15 Δ: 0.15 to less than 0.25 x: 0.25 or more

[Comparative Example 1]
A two-component developer was produced in the same manner as in Example 1 except that it was replaced with the carrier 2, and the image was printed and evaluated. Although it was initially good, the halftone uniformity and solid uniformity deteriorated due to durability. did. The evaluation results are shown in Table 1. This is presumably because the mixing property with the toner deteriorated due to the small particle size of the carrier.

[Comparative Example 2]
A two-component developer was produced in the same manner as in Example 1 except that the carrier 3 was used, and the image was printed and evaluated. As a result, the fog and solid uniformity deteriorated due to durability. The evaluation results are shown in Table 1. This is presumably because the charge imparting ability to the toner deteriorates due to the large particle size of the carrier, resulting in non-uniform charging.

[ Comparative Example 3 ]
A two-component developer was produced in the same manner as in Example 1 except that it was replaced with the carrier 4, and imaged and evaluated. As a result, although fog and halftone uniformity slightly deteriorated due to durability, there was a practical problem. No results were obtained. The evaluation results are shown in Table 1. This is presumed that since the carrier core material is ferrite, the stress from the toner is increased, and the charge imparting ability of the carrier is lowered due to durability.

[Comparative Example 4 ]
A two-component developer was produced in the same manner as in Example 1 except that the carrier 5 was used, and the image was printed and evaluated. As a result, the fog deteriorated and the halftone uniformity deteriorated due to durability. The evaluation results are shown in Table 1. This is presumably because the resin amount of the carrier is small and the apparent density is large, so that the toner is easily damaged from the carrier, the toner is liable to be deteriorated, and the toner is not uniformly charged.

[Comparative Example 5 ]
A two-component developer was produced in the same manner as in Example 1 except that the carrier 6 was used, and the image was printed and evaluated. As a result, the fog deteriorated and the solid uniformity deteriorated due to durability. The evaluation results are shown in Table 1. This is presumably because the amount of resin in the carrier is large and charges are accumulated on the carrier, making it impossible to uniformly charge the toner.

[ Comparative Example 6 ]
A two-component developer was produced in the same manner as in Example 1 except that the carrier 7 was used, and the image was printed and evaluated. As a result, although fog was slightly deteriorated, a result having no practical problem was obtained. The evaluation results are shown in Table 1. This is presumably because toner spent easily occurs because the heavy metal is contained, and the toner is not uniformly charged.

[Example 2 ]
In Example 1, the same procedure was performed except that the magnetic toner 2 was used. As shown in Table 1, although the image density and the solid uniformity were slightly deteriorated, there were obtained practically no problems. This is presumably because the toner saturation magnetization has increased.

[Example 3 ]
Example 1 was carried out in the same manner except that the magnetic toner 3 was used. As shown in Table 1, although the image density was lowered, a practically acceptable result was obtained. This is presumed to be due to the fact that the developability deteriorated due to the high saturation magnetization of the toner.

[Example 4 ]
In Example 1, the same procedure was carried out except that the magnetic toner 4 was used. As shown in Table 1, although the halftone reproducibility and Dmax were slightly deteriorated, the image density was clearly higher than that in Example 2 , and there were practical problems. No results were obtained. This is presumably due to the saturation magnetization of the toner.

[Example 5 ]
In Example 1, the same procedure was performed except that the magnetic toner 5 was used. As shown in Table 1, both fogging and solid uniformity were inferior to those in Example 4, but there were obtained practically no problems. It was. This is also presumed to be caused by toner saturation magnetization.

[Example 6 ]
In Example 1, the same procedure was performed except that the magnetic toner 6 was used. As shown in Table 1, although the results were inferior to Example 1 in terms of fogging, solid uniformity, etc., there was no practical problem. Obtained. This is presumably because the toner production method is a kneading / pulverization method, and the wax is easily exposed on the toner surface.

[Example 7 ]
In Example 2 , the same procedure was carried out except that the magnetic toner 7 was used. As shown in Table 1, all results such as fogging and solid uniformity were inferior to those in Example 2, but there were no practical problems. Obtained. This is presumed that the toner has a non-core / shell structure and the wax is easily exposed on the toner surface.

[Example 8 ]
In Example 2 , the same procedure was carried out except that the magnetic toner 8 was used. As shown in Table 1, all the fogging, solid uniformity and the like were inferior to those in Example 2, but there were no practical problems. Obtained. This is also presumed that the toner has a non-core / shell structure and the wax is easily exposed on the toner surface.

FIG. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Developing apparatus 3 Developer 3a Magnetic carrier 3b Toner 4 Developing sleeve 5 Magnet roller 6 First doctor blade 7 Second doctor blade 8 Toner hopper 11 Developer accommodating member 20 Toner supply opening A Developer accommodating section A

Claims (5)

While rotating the developing sleeve having the magnetic field generating means inside, the developer containing the magnetic toner and the magnetic carrier in the developer accommodating portion is removed from the developer accommodating member on the downstream side in the developer conveying direction of the developer accommodating portion. And a developer containing portion for containing the developer blocked by the developer regulating member, and the developer containing portion from the upstream side in the developer carrying direction. A magnetic toner containing portion having a magnetic toner replenishment opening facing the surface of the developing sleeve at an adjacent position, and the developer in the developer containing portion is moved by the movement of the developer accompanying the developer conveyance on the developing sleeve. A developing device that takes in the magnetic toner in the magnetic toner accommodating portion into the developer accommodating portion according to the capacity of
A second regulating member for regulating the amount of developer carried on the developing sleeve is provided in the vicinity of the magnetic toner replenishing opening of the developer accommodating portion so as to face the developing sleeve. The lower surface of the opening is formed so as to be inclined downward toward the developing sleeve side, and when the magnetic toner concentration in the developer containing portion is high, the developer overflows into the magnetic toner replenishing opening, In the two-component developer used in the developing device in which the magnetic toner is supplied from the magnetic toner replenishing opening to the developer containing portion when the magnetic toner concentration in the developer containing portion is low,
The magnetic carrier is a magnetic fine particle-dispersed resin carrier containing at least a magnetic core material having inorganic compound particles and a binder resin and a coating resin, and a resin content that is a total of the coating resin and the binder resin is 5 to 25% by mass, the apparent density is 1.2 to 2.3 g / cm ³ , the average particle size is 25 to 55 μm, 21 μm or less is 0.01 to 12% by volume, and 72 μm or more. A two-component developer characterized by being 1.0% by volume or less. ^2. The two-component developer according to claim 1, wherein the magnetic toner has a saturation magnetization of 1.0 to 35.0 Am ² / kg. The two-component developer according to claim 1 or 2, wherein the magnetic toner has a saturation magnetization of 5.0 to 25.0 Am ² / kg. While rotating the developing sleeve having the magnetic field generating means inside, the developer containing the magnetic toner and the magnetic carrier in the developer accommodating portion is removed from the developer accommodating member on the downstream side in the developer conveying direction of the developer accommodating portion. And a developer containing portion for containing the developer blocked by the developer regulating member, and the developer containing portion from the upstream side in the developer carrying direction. A magnetic toner containing portion having a magnetic toner replenishment opening facing the surface of the developing sleeve at an adjacent position, and the developer on the developing sleeve is moved by the movement of the developer along the developer conveying on the developing sleeve. In the developing device that takes in the magnetic toner in the magnetic toner container into the developer according to the magnetic toner concentration,
A second regulating member for regulating the amount of developer carried on the developing sleeve is provided in the vicinity of the magnetic toner replenishing opening of the developer accommodating portion so as to face the developing sleeve. The lower surface of the opening is formed so as to be inclined downward toward the developing sleeve side, and when the magnetic toner concentration in the developer containing portion is high, the developer overflows into the magnetic toner replenishing opening, When the magnetic toner concentration in the developer accommodating portion is low, magnetic toner is replenished to the developer accommodating portion from the magnetic toner replenishing opening,
The magnetic carrier constituting the developer is a magnetic fine particle dispersed resin carrier containing at least a magnetic core material having inorganic compound particles and a binder resin and a coating resin, and the total of the coating resin and the binder resin A certain resin content is 5 to 25% by mass, an apparent density is 1.2 to 2.3 g / cm ³ , an average particle size is 25 to 55 μm, and 21 μm or less is 0.01 to 12% by volume. A developing device using a magnetic carrier having a thickness of 72 μm or more and 1.0% by volume or less.   5. The developing device according to claim 4, further comprising a peeling member that faces the surface of the developing sleeve in a non-contact manner in the developer accommodating portion and peels an upper layer portion of the developer carried and conveyed by the developing sleeve.

Images