JP2008090182A - Electrostatic latent image developing carrier and electrostatic latent image developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic latent image developing carrier which forms a high quality image and an electrostatic latent image developer. <P>SOLUTION: The electrostatic latent image developing carrier is formed with a first resin film by a resin on the surface of magnetic particles containing magnetic powder in the resin and further is formed with a second conductive resin film by a conductive resin on the surface of the first resin film, in which the saturation magnetization of the electrostatic latent image developing carrier, defined as σs, and the true specific gravity of the electrostatic latent image developing carrier, defined as D, are 175emu/cm<SP>3</SP>≤σsxD≤250emu/cm<SP>3</SP>, and the thickness of the second conductive resin film is thicker than the thickness of the first resin film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic latent image developing carrier and an electrostatic latent image developing developer used for electrophotography and electrostatic recording.

  In electrophotography, an electrostatic latent image is formed on a latent image holding member (photoreceptor) by charging and exposure processes, developed with toner, the developed image is transferred onto a transfer member, and fixed by heating or the like to obtain an image. Developers used in such an electrophotographic method are roughly classified into a one-component developer using a toner in which a colorant is dispersed in a binder resin and a two-component developer composed of the toner and a carrier. Can do. Two-component developers are currently widely used because of their high controllability because the carrier has a charging / conveying function. The two-component developer has a feature such that the carrier has functions such as stirring, transporting, and charging of the developer, and the function as the developer is separated, so that the controllability is good.

  Although iron powder carriers have been used for a long time as carriers, many defects have been recognized in iron powder carriers, and recently, carriers in which the surface of ferrite, nickel, magnetic material-dispersed resin, etc. are coated with resin are used. Has been proposed.

  In particular, a magnetic powder-dispersed resin carrier that is easy to provide a relatively spherical carrier with a low specific gravity can be expected to be effective in reducing stress on the toner by stirring in the developing unit. Is preferable.

  However, such a low specific gravity and relatively spherical carrier sometimes slips on the sleeve and cannot ensure sufficient transportability. In order to improve the conveyance stability, Patent Document 1 proposes a technique having fine irregularities on the surface of a magnetic powder-dispersed carrier. However, since this method forms irregularities in the solvent removal step of the carrier manufacturing process, the irregularities may not be arbitrarily adjusted. Further, Patent Document 2 proposes a carrier in which an amorphous carrier core material is coated with a resin. However, since macro irregularities exist on the surface of the amorphous core material, a resin using an amorphous carrier core material is used. When coating, the resin of ii section is coated by the concave part, and the convex part is only thinly coated with resin, or the resin is not coated, and the resistance change due to the peeling of the resin film over time is likely to occur. There is a risk.

  Further, the above-described resin peeling of the resin-coated carrier with the lapse of time of running causes a change in resistance and causes deterioration of image quality. In particular, a carrier using an amorphous core material has a problem that resistance changes easily occur as described above. In order to reduce the change in resistance over time, for example, in Patent Document 3, a resin inner layer made of a synthetic resin having no conductive material and a synthetic resin in which the conductive material is dispersed around a core made of a sphere There has been proposed a carrier coated with a resin coating layer composed of two resin surface layers. As a result, even if the carrier resin part is peeled off, the resistance change can be suppressed. However, since a resin layer having a high resistance appears locally on the surface, the counter charge generated at the time of development is hindered. As a result, white spots on the rear end and white spots on the density boundary portion are likely to occur. Also, when peeling occurs on a part of the resin inner surface layer made of synthetic resin that does not have a conductive material, the surface layer of the core material particles is exposed on the “surface”, which may cause carrier adhesion to the photoreceptor. was there.

  In recent years, since it is easy to provide a carrier having a low specific gravity and a relatively spherical shape, a carrier obtained by coating a resin using a resin-dispersed core material having a structure in which magnetic powder is dispersed in a resin matrix has been proposed. . In general, the surface of the core material is coated with a resin to impart a charging function or the like. However, the resin-dispersed core material as described above has fine irregularities on the particle shape and surface. Therefore, even when resin coating is performed using a resin-dispersed core material, uniform resin coating can be performed, which is effective in suppressing resistance due to peeling of the resin film.

  However, the resin-coated carrier with the resin-dispersed core material coated with resin has excellent resin coating uniformity due to the effect of fine irregularities on the surface. Therefore, the resin-coated carrier is adjusted to a predetermined resistance with little core material exposed. Therefore, there are few surface effective site portions that promote the relaxation of the counter charge generated during development. Furthermore, due to the structure in which the magnetic powder particles are dispersed in the resin, there is no site that promotes counter charge relaxation in a completely continuous phase. By overlapping these two phenomena, the resin-coated carrier whose resin-dispersed core material is resin-coated has a sufficient counter-charge extinction field even though it exhibits the same resistance as the amorphous carrier, and the rear end described above. There is a possibility that white spots may occur.

  On the other hand, in order to suppress the occurrence of the trailing edge whiteout phenomenon, the resistance of the resin-coated carrier in which the surface of the resin-dispersed core material is resin-coated is designed in a lower resistance region than that of the amorphous carrier. Although it is thought that it can be suppressed, there is a possibility that adhesion of the carrier to the photoreceptor due to peeling of the resin film that occurs with the lapse of time of running easily occurs. However, if the resin layer is thickened to prevent carrier adhesion due to peeling of the resin coating, there is a problem in manufacturability, and there is a limit to thickening from the viewpoint of film strength.

JP-A-5-197212 JP 2002-116582 A JP 2005-345676 A

  The present invention is a resin-coated carrier having a high sphericity and coated with a resin-dispersed core material. Even if the resin coating peels off over the course of running, It is an object to provide a carrier for developing an electrostatic charge image capable of suppressing an edge white spot phenomenon, and a highly reliable developer capable of obtaining a high quality image.

  As a result of repeated detailed studies on the above problems, the present inventors have found that the above object can be achieved by the constitution of the following invention, and have completed the present invention. That is, the features of the present invention are as follows.

(1) A first resin film made of resin is formed on the surface of magnetic particles containing magnetic powder in the resin, and a second conductive resin film made of conductive resin is formed on the surface of the first resin film. 175 emu / cm ³ ≦ σs, where σs is the saturation magnetization of the carrier for electrostatic latent image development, and D is the true specific gravity of the carrier for electrostatic latent image development. × D ≦ 250 emu / cm ³ , and the electrostatic latent image developing carrier in which the second conductive resin film is thicker than the first resin film.

  (2) The electrostatic latent image developing carrier according to (1), wherein the first resin film has a thickness smaller than the volume average particle diameter of the magnetic particles.

  (3) An electrostatic latent image developing developer comprising the electrostatic latent image developing carrier described in (1) or (2) above and toner particles.

  According to the first aspect of the present invention, the magnitude of the saturation magnetization per carrier volume of “σs × D” is set in the above range, and the thicknesses of the first resin film and the second conductive resin film are adjusted. As a result, even if the second resin coating is peeled off during running, the carrier adhesion to the photoreceptor is suppressed, and the counter charge generated by the toner consumption in the magnetic brush during development is promoted and maintained. In particular, it is possible to stably obtain a good image with no trailing edge white spots and density boundary white spots.

  According to the invention of claim 2, even when a part of the second conductive resin film is peeled off or the resin wear occurs during running, the first resin coating and the magnetic powder are exposed at the same time. Since the first resin coating layer and the magnetic powder are spot-distributed, even if a part of the second conductive resin film is peeled off, the carrier adhesion phenomenon to the photoconductor and the white edge at the rear end are maintained for a long time. Omission phenomenon can be suppressed.

  According to the invention of claim 3, by combining the carrier and the toner particles described above, it is possible to obtain a high quality image in which the trailing edge white spot phenomenon is suppressed for a long period of time.

  Hereinafter, the present invention will be described in detail.

[Electrostatic latent image development carrier]
The electrostatic latent image developing carrier of the present invention will be described below. The “electrostatic latent image developing carrier” is hereinafter abbreviated as “carrier”.

In the carrier of the present embodiment, a first resin film made of resin is formed on the surface of magnetic particles containing magnetic powder in a resin, and second conductive material made of conductive resin is further formed on the surface of the first resin film. 175 emu, where the electrostatic latent image developing carrier on which the photosensitive resin film is formed, where s is the saturation magnetization of the electrostatic latent image developing carrier and D is the true specific gravity of the electrostatic latent image developing carrier. The electrostatic latent image developing carrier is / cm ³ ≦ σs × D ≦ 250 emu / cm ³ , and the second conductive resin film is thicker than the first resin film.

As a device for measuring the saturation magnetization σs (emu / g or Am ² / kg) of the carrier, a vibration sample type magnetic measuring device VSMP10-15 (manufactured by Toei Kogyo Co., Ltd.) is used. The measurement sample is packed in a cell having an inner diameter of 7 mm and a height of 5 mm and set in the apparatus. The measurement applies an applied magnetic field and sweeps up to 1000 oersted. Next, the applied magnetic field is decreased to create a hysteresis curve on the recording paper. Saturation magnetization, residual magnetization, and coercive force are obtained from the curve data. In the present invention, the saturation magnetization σs indicates the magnetization measured in a 1000 oersted magnetic field. The true specific gravity D (g / cm ³ ) of the carrier of the present invention was measured with a multi-volume density meter (manufactured by Micromeritics).

The “σs × D” (emu / cm ³ ) represents the strength of magnetization per volume, and is obtained by multiplying the true specific gravity of the carrier by the strength of the magnetization of the carrier.

When the above-mentioned magnetization intensity per volume “σs × D” is less than 175 emu / cm ³ , not only carrier scattering due to insufficient magnetic force is promoted in a high-speed machine, but also the trailing edge white spot phenomenon is likely to occur. . On the other hand, when “σs × D” exceeds 250 emu / cm ³ , the magnetic brush becomes hard, so that not only the graininess is likely to deteriorate but also carrier adhesion is likely to occur.

  Further, since the thickness of the second conductive resin film is thicker than the thickness of the first resin film, even if the resin film peels off over time, even if the film peeling over time occurs, Since the site that promotes the relaxation of the generated counter charge appears in a point distribution on the carrier surface, a resin site part that suppresses the reduction in resistance appears between the counter charge promoting site and the site part, so it is stable over a long period of time. Resistance can be provided. That is, both the site portion that suppresses the reduction in resistance derived from the first resin coating coated on the surface of the core material and the counter charge promoting site portion derived from the magnetic particles are not continuous and are simultaneously exposed in a point distribution. Stable resistance can be provided by the synergistic action. Therefore, when the thickness of the first resin film is larger than the thickness of the second conductive resin film, the effect of relaxing the counter charge cannot be sufficiently exhibited. There is a possibility that the phenomenon is likely to occur.

  In the carrier of the present embodiment, the thickness of the first resin film is thinner than the volume average particle diameter of the magnetic particles. Moreover, the sum total of the thickness of the 1st resin coating layer and the thickness of the 2nd conductive resin coating layer is 0.1-5 micrometers, Preferably the range of 0.3-3 micrometers is suitable. If the thickness of the coating resin layer is smaller than 0.1 μm, it is difficult to form a uniform and flat coating resin layer on the surface of the magnetic particles. On the other hand, if it is larger than 5 μm, carriers are aggregated and it is difficult to obtain a uniform carrier.

  As the magnetic powder forming the magnetic particles, any conventionally known powder can be used, and ferrite, magnetite, and maghematite are particularly preferably selected. In particular, magnetite and maghematite are selected as the ferromagnetic magnetic powder, and for example, iron powder is known as another magnetic particle. In the case of iron powder, the specific gravity is large and the toner is easily deteriorated. Therefore, ferrite, magnetite, and maghematite are more stable. An example of ferrite is generally represented by the following formula.

(MO) _X (Fe ₂ O ₃ ) _Y
(In the formula, M contains at least one selected from Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti, Ni, Sn, Sr, Al, Ba, Co, Mo and the like: X, Y represents the molar ratio by weight and satisfies the condition X + Y = 100)

The M is preferably a ferrite particle which is one or a combination of Li, Mg, Ca, Mn, Sr and Sn, and the content of other components is 1% by weight or less. By adding Cu, Zn, and Ni elements, the resistance tends to be low and charge leakage is likely to occur. In addition, the resin tends to be difficult to coat, and the environmental dependency tends to deteriorate. Furthermore, since it is a heavy metal, the stress given to a carrier becomes strong because it is heavy, and it may have a bad influence on life property. From the viewpoint of safety, in recent years, those to which Mn or Mg element is added have become widespread. Ferrite core material is suitable, and the raw material of magnetic particles is Fe ₂ O ₃ as an essential component, and the magnetic fine particles contained in the magnetic fine particle-dispersed resin core are ferromagnetic iron oxides such as magnetite and maghemite. Particle powder, spinel ferrite particle powder containing one or more metals other than iron (Mn, Ni, Zn, Mg, Cu, etc.), magnet plumbite type ferrite particle powder such as barium ferrite, oxide film on the surface Fine particles of iron or iron alloy can be used.

  Specific examples of magnetic powder include iron-based oxides such as magnetite, gamma iron oxide, Mn—Zn ferrite, Ni—Zn ferrite, Mn—Mg ferrite, Li ferrite, and Cu—Zn ferrite. Can be mentioned. Among these, inexpensive magnetite can be more preferably used.

The magnetic susceptibility σ of the magnetic particles of the composite magnetic particles prepared as described above is measured by a BH tracer method using a VSM (vibration sample method) measuring device in a magnetic field of 1 kOe, and the magnetization value σ1000 is 50 to 50- The range is 90 Am ² / kg (emu / g), preferably 70 to 85 Am ² / kg (emu / g). When σ1000 is less than 50 Am ² / kg (emu / g), the magnetic attraction force to the developing roll becomes weak and adheres to the photoreceptor, causing image defects, which is not preferable. On the other hand, when σ1000 exceeds 90 Am ² / kg (emu / g), the magnetic brush becomes too hard, and the photoreceptor is easily rubbed and easily damaged.

  The carrier of the present invention has a volume average particle diameter of 10 to 100 μm, preferably 20 to 50 μm. When the volume average particle size is less than 10 μm, the developer is likely to scatter from the developing device, and when it is more than 100 μm, it is difficult to obtain a sufficient image density.

  Furthermore, the carrier of the present embodiment is coated with a resin for forming the first resin coating on the composite magnetic particles, and the surface of the first resin coating is at least a conductive fine powder in the coating resin. A second conductive resin film in which is dispersed is formed, and the carrier coverage after the two-layer coating is 90 to 100%.

  By setting the carrier coverage to 90 to 100%, not only can the carrier resistance change be suppressed even in long-term use, but also the carrier strength is tough. That is, the amount of irregular fine powder that causes deterioration of the surface of the latent image carrier does not increase even when used for a long time, and a stable high-quality product and high reliability can be obtained.

  When the carrier coverage is less than 90%, the carrier strength is lowered, and the surface of the magnetic particles cannot be sufficiently covered, and the release of the resin coating layer is promoted at the exposed portion of the magnetic particles and the resin coating interface. There is a possibility that the carrier electric resistance characteristic is changed due to wear of the coating layer. In addition, when particles such as a resistance adjusting agent or a charge control agent are added to the resin coating layer, the strength of the resin coating layer may be reduced. Thus, when the coverage is less than 90%, the amount of irregular carrier fine powder is likely to increase with long-term use, and the carrier resistance gradually decreases, so the carrier adhesion deteriorates over time, and image quality and reliability are improved. I can't get sex.

  As a result, the magnetic particle surface is almost completely concealed by the resin coating layer, and the unevenness of the carrier surface is reduced, thereby not only reducing the frictional energy, but also maintaining the electric resistance characteristics while maintaining the electric resistance characteristics. The anchor effect of the coating layer functions more effectively, and the detachment of the resin coating layer can be improved.

  Examples of the coating resin formed on the magnetic particles include polyolefin resins such as polyethylene, polypropylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, and polyvinyl chloride. Carbazole, polyvinyl ether and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin composed of organosiloxane bond or a modified product thereof; fluororesin such as polytetrafluoroethylene, polyvinyl fluoride Polyvinylidene fluoride, polychlorotrifluoroethylene; polyesters; polyurethanes; polycarbonates, amino resins such as urea-formaldehyde Resins; epoxy resins. These may be used alone or in combination with a plurality of resins.

  The method of forming the coating resin layer on the magnetic particles includes the dipping method in which the magnetic particles are immersed in the coating resin layer forming solution, the spray method in which the coating resin layer forming solution is sprayed on the surface of the magnetic particles, and the magnetic particles are fluidized air. A fluidized bed method in which the coating resin layer forming solution is sprayed in a state of being suspended by the above, a kneader coater method in which the magnetic particles and the coating resin layer forming solution are mixed in a kneader coater and the solvent is removed.

  The solvent used in the coating resin layer forming solution is not particularly limited as long as it dissolves the coating resin, and examples thereof include aromatic hydrocarbons such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. , Ethers such as tetrahydrofuran and dioxane can be used. Examples of the method for dispersing the conductive fine powder include a sand mill, a dyno mill, and a homomixer.

  In the carrier, the second conductive resin coating coated on the composite magnetic particles described above has conductive fine powder dispersed in a binder resin from the viewpoint of charge control and resistance control. The material of the conductive fine powder is not particularly limited as long as it has a desired shape and dynamic electrical resistance. For example, fine particles such as titanium oxide, zinc oxide, aluminum borate, potassium titanate, barium sulfate, etc. A composite system in which the surface is coated with a conductive metal oxide, or a simple system of carbon black, magnetite, or conductive metal oxide is preferable. Here, examples of the conductive metal oxide include metal oxides doped with antimony (for example, antimony-doped tin oxide), oxygen-deficient metal oxides (for example, oxygen-deficient tin oxide), and the like.

  As the conductive fine powder containing the metal oxide as a main component, needle-shaped and spherical shapes are preferably used, but needle-shaped ones are more preferable. The term “needle” as used herein refers to the ratio of the major axis (fiber length) to the minor axis (fiber diameter) (major axis / minor axis; hereinafter referred to as “aspect ratio”), and this aspect ratio is 3 or more. Preferably, it is 5 or more. The acicular conductive fine powder preferably has a major axis of 0.05 to 20 μm. Even if the aspect ratio is 3 or more, if the major axis is shorter than 0.05 μm, the filler may be destroyed in the process of dispersing in the binder resin, and the effect may be reduced, while the major axis is 20 μm. If it is longer, the conductive fine powder may be easily detached from the coat layer. The minor axis of the acicular inorganic powder is preferably 0.01 to 1 μm. Outside this range, dispersibility may deteriorate and carrier characteristics may become uneven. The spherical conductive fine powder preferably has a volume average particle size of 0.01 to 1 μm. Outside these ranges, the dispersibility may be deteriorated, and the conductive fine powder may be easily detached from the coat layer.

In the carrier, the static electrical resistance of the conductive fine powder is preferably 1 to 1 × 10 ⁶ Ω · cm. If the static electrical resistance is less than 1 Ω · cm, brush marks are likely to occur. On the other hand, if it exceeds 1 × 10 ⁶ Ω · cm, even if the content of the conductive fine powder is increased (for example, 40% by volume or more) In some cases, a predetermined resistance cannot be obtained.

  In the carrier, the content of the conductive fine powder in the coat resin layer is preferably 25 to 45% by volume, and preferably 30 to 40% by volume. When this content is less than 25% by volume, a predetermined resistance may not be obtained. On the other hand, when it exceeds 45% by volume, film formation of the coating layer is poor and charge leakage tends to occur. It may be easier to get a brush mark.

The electric resistance of the carrier on which the coating resin layer is formed is 1 × 10 ⁵ to 1 × 10 ¹⁴ Ω · cm, preferably 1 × 10 ⁹ to 1 × 10 ¹² Ω · cm when the measurement electric field is 10000 V / cm. The range is appropriate.

  The chargeability of the carrier on which the coating resin layer is formed is preferably 15 to 50 μC / g. When the chargeability of the carrier is less than 15 μC / g, toner contamination on the day image portion occurs (fogging occurs) and a high-quality color image can be obtained, while the chargeability of the carrier is 50 μC. When it exceeds / g, it becomes difficult to obtain a sufficient image density.

If the electric resistance of the carrier on which the coating resin layer is formed is smaller than 1 × 10 ⁵ Ω · cm, the electric charge easily moves on the carrier surface, and image defects such as brush marks are likely to occur, and the printing operation is not performed for a while. If left unattended, the chargeability becomes too low, and background stains occur on the first print. If the electric resistance of the carrier on which the coating resin layer is formed is greater than 1 × 10 ¹⁴ Ω · cm, not only a good solid image can be obtained, but if the continuous printing is repeated many times, the toner charge becomes too large and the image density becomes too high. It will go down.

The electrokinetic resistance when measured in the form of a carrier magnetic brush is 1 × 10 to 1 × 10 ⁹ Ω · cm, preferably 1 × 10 ³ to 1 × 10 ⁸ Ω, under an electric field of 10 ⁴ V / cm. A range of cm is appropriate. If the dynamic electrical resistance is less than 1 × 10 Ω · cm, image defects such as brush marks are likely to occur, and if it is greater than 1 × 10 ⁸ Ω · cm, it is difficult to obtain a good solid image. The electric field of 10 ⁴ V / cm is close to the developing electric field in an actual machine, and the dynamic electric resistance is a value under this electric field.

From the above, the electrokinetic resistance when the carrier and the toner are mixed is suitably in the range of 1 × 10 ⁵ to 1 × 10 ⁹ Ω · cm under an electric field of 10 ⁴ V / cm. On the other hand, if it is less than 1 × 10 ⁵ Ω · cm, the resolution deteriorates due to background stains due to a decrease in toner chargeability after standing after printing, and thickening of line images due to over-development. If it exceeds 1 × 10 ⁹ Ω · cm, problems such as the inability to obtain a high-quality image due to a decrease in the developability of the solid image edge occur.

The dynamic electrical resistance of the carrier is obtained as follows. A magnetic brush is formed by placing a carrier of about 30 cm ³ on the developing roll (the magnetic field of the sleeve surface of the developing roll is 1 kOe), and a plate electrode having an area of 3 cm ² is placed on the developing roll at intervals of 2.5 mm. Make them face each other. A voltage is applied between the developing roll and the plate electrode while rotating the developing roll at a rotation speed of 120 rpm, and the current flowing at that time is measured. The dynamic electric resistance is obtained from the obtained current-voltage characteristics using Ohm's law equation. It is well known that there is generally a relationship of ln (I / V) ∝V × 1/2 between the applied voltage V and the current I at this time. When the dynamic electrical resistance is quite low as in the carrier used in the present invention, measurement may not be possible because a large current flows in a high electric field of 10 ³ V / cm or more. In such a case, three or more points are measured in a low electric field, and an electric field of 10 ⁴ V / cm is extrapolated by the least square method using the above relational expression.

[Developer for electrostatic latent image development]
Here, the electrostatic latent image developing developer used is a two-component developer composed of toner and carrier. However, the toner described below may be a magnetic toner or a non-magnetic toner. The “electrostatic latent image developing developer” is hereinafter abbreviated as “developer”.

  In the present invention, as the toner, for example, in a dispersion obtained by dispersing at least resin particles, the aggregated particles are formed by heating to a temperature below the glass transition point of the resin particles to prepare an aggregated particle dispersion. A first step, a second step of adding and mixing a fine particle dispersion in which fine particles are dispersed in the aggregated particle dispersion to form the adhered particles by adhering the fine particles to the aggregated particles; and A toner produced by a so-called agglomeration and coalescence method including the third step of fusing by heating can be used.

  The characteristics of this toner are that the particle shape is relatively round and the particle size distribution is narrow, the toner surface is relatively uniform, the charging property is high, and the charge distribution is narrow and good.

  Therefore, since the developer for developing an electrostatic charge image obtained by mixing with the carrier has a very high fluidity and good developability, a good product can be obtained as a high-quality color developer.

  Other toners that can be used include polymerized toner, dissolved suspension toner, emulsion aggregation toner, or kneading / pulverizing / classifying / spheronizing toner.

  Here, as an example of the toner used for the developer, an emulsion aggregation toner will be described.

  For example, as disclosed in JP-A-10-026842, JP-A-10-133423, JP-A-10-198070, JP-A-11-231570, etc., this toner has at least resin particles dispersed therein. A first step of forming aggregated particles by heating to a temperature below the glass transition point of the resin particles to prepare an aggregated particle dispersion, and dispersing the fine particles in the aggregated particle dispersion A second step of adding and mixing the resulting fine particle dispersion to adhere the fine particles to the agglomerated particles to form the adhered particles, and a third step of heating and fusing the adhered particles. The toner is produced by a method for producing a toner for developing an electrostatic image.

  Adjustment of the volume average particle diameter, shape, and distribution can be adjusted by adjusting the aggregated particle dispersion, the conditions for forming the adhered particles, and the conditions for heating and fusing the adhered particles.

  The dispersion is obtained by dispersing at least resin particles. The resin particles are resin particles. Examples of the resin include thermoplastic binder resins. Specifically, homopolymers or copolymers (styrene-based resins) of styrenes such as styrene, parachlorostyrene, and α-methylstyrene; acrylic Methyl acid, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, methacrylic acid 2 -Homopolymers or copolymers of vinyl group esters such as ethylhexyl (vinyl resins); Homopolymers or copolymers of vinyl nitriles such as acrylonitrile and methacrylonitrile (vinyl resins); A single vinyl ether such as ether or vinyl isobutyl ether Polymers or copolymers (vinyl resins); homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone (vinyl resins); ethylene, propylene, butadiene, isoprene, etc. Homopolymers or copolymers of olefins (olefin resins); non-vinyl condensation resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, and polyether resins, and these non-vinyl condensation resins And a graft polymer of a vinyl monomer and the like. These resins may be used alone or in combination of two or more.

  Among these resins, styrene resins, vinyl resins, polyester resins, and olefin resins are preferable. Copolymers of styrene and n-butyl acrylate, n-butyl acrylate, bisphenol A / fumaric acid copolymer. Particularly preferred is a copolymer of styrene and olefin.

  The volume average particle diameter of the resin particles is usually 1 μm or less and preferably 0.01 to 1 μm. When the volume average particle size exceeds 1 μm, the particle size distribution of the finally obtained electrostatic image developing toner is broadened or free particles are generated, which tends to deteriorate performance and reliability. On the other hand, when the volume average particle size is within the above range, there are no disadvantages, and it is advantageous in that uneven distribution among toners is reduced, dispersion in the toner is improved, and variations in performance and reliability are reduced. . The volume average particle diameter in the previous period can be measured using, for example, a laser diffraction method (Horiba, Ltd .: LA-700).

  Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, and brilliant. Carmine 6B, Daypon Oil Red, Pyrazolone Red, Risor Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalley Various pigments such as acridine, xanthene, azo, benzoquinone, azine, anthraquinone, dioxadi , Thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazine, thiazole, xanthene, and the like. . These colorants may be used alone or in combination of two or more.

  The volume average particle size of the colorant is usually 1 μm or less, preferably 0.01 to 1 μm. When the volume average particle size exceeds 1 μm, the particle size distribution of the finally obtained electrostatic image developing toner is broadened or free particles are generated, which tends to deteriorate performance and reliability. On the other hand, when the volume average particle size is within the above range, there are no disadvantages, and it is advantageous in that uneven distribution among toners is reduced, dispersion in the toner is improved, and variations in performance and reliability are reduced. . In addition, the said volume average particle diameter can be measured using a laser diffraction method (Horiba Seisakusho: LA-700), for example.

  In the present invention, other components such as a release agent, an internal additive, a charge control agent, an inorganic particle, a lubricant, and an abrasive may be dispersed in the dispersion according to the purpose. In this case, other particles may be dispersed in a dispersion obtained by dispersing resin particles, or a dispersion obtained by dispersing other particles is mixed in a dispersion obtained by dispersing resin particles. May be.

  Examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide. Plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax -Petroleum wax; and modified products thereof.

  These waxes are dispersed in water together with a polymer electrolyte such as an ionic surfactant, polymer acid, polymer base, etc., heated above the melting point, and can be applied with a strong shearing force or pressure discharge type. When processed using a disperser, it can be easily made into fine particles of 1 μm or less.

  Examples of the charge control agent include quaternary ammonium salt compounds, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments. In addition, as the charge control agent in the present invention, a material that is difficult to dissolve in water is preferable in terms of controlling ionic strength that affects stability during aggregation and fusion and reducing wastewater contamination.

  Examples of the inorganic particles include all particles usually used as external additives on the toner surface, such as silica, alumina, titania, calcium carbonate, magnesium carbonate, calcium phosphate, and cerium oxide. Examples of the lubricant include fatty acid amides such as ethylene bisstearamide and oleic acid amide, and fatty acid metal salts such as zinc stearate and calcium stearate. Examples of the abrasive include the aforementioned silica, alumina, cerium oxide, and the like.

  The ratio of the toner in preparing the developer by mixing the toner and the carrier is 1 to 15% by weight, preferably 3 to 12% by weight of the whole developer.

If the toner ratio is less than 1% by weight, it is difficult to obtain a sufficient image density, and a solid image is difficult to be uniform. On the other hand, if the amount exceeds 15% by weight, the toner coverage on the carrier surface exceeds 100%, and the charge amount decreases (when the average value of the average charge amount is less than 15 μC / g). Fog) A high-quality color image cannot be obtained. For example, if the amount exceeds 3% by weight, the toner coverage on the carrier surface approaches 100%, so that the resistance value as a developer is extremely increased, and is in the range of 1 × 10 ⁵ to 1 × 10 ⁸ Ω · cm. Therefore, a good and high-quality color image such as a blur of the image edge portion cannot be obtained.

  However, in a low-humidity environment, if the toner ratio is less than 1% by weight, a high charge amount (the absolute value of the average charge amount exceeds 25 μC / g) tends to occur, and it may be difficult to obtain a sufficient image density. Therefore, it is preferable to select the toner ratio so that the absolute value of the charging property is in the range of 15 to 50 μC / g depending on the environment.

  In the toner production method, the above-described resin fine particle dispersion, colorant dispersion, and the like are mixed to prepare a uniform mixed particle dispersion, and then a soluble inorganic metal salt is added to the dispersion medium and mixed to obtain a desired agglomeration. Get particles. At that time, resin fine particles, colorant, and if necessary, the above inorganic fine particles may be added at once, or the fine particle components are added step by step, and the structure of the aggregated particles is, for example, a core-shell structure, You may provide the structure which inclined the component to the radial direction of particle | grains. In that case, the resin fine particle dispersion, the colorant particle dispersion, the release agent fine particle dispersion and the like are mixed and dispersed, and the aggregated particles are grown until the particle size reaches a certain level. If necessary, additional resin fine particles may be added to the surface of the aggregated particles by adding a resin fine particle dispersion or the like. By covering the surface of the agglomerated particles with the additional resin fine particles, it is possible to prevent the colorant, release agent, etc. from being exposed to the toner surface, and it is effective in suppressing poor charging and uneven charging due to these exposures. is there.

  In the agglomeration step for forming the agglomerated particles described above, an inorganic metal salt having a valence of 2 or more is used as the aggregating agent. The larger the valence of the inorganic metal, the stronger the agglomeration force, and the more stable the aggregation can be controlled. Therefore, an unagglomerated material is hardly generated and an excellent particle size distribution can be obtained. As the tetravalent or higher inorganic metal salt polymer, polyaluminum chloride, polyaluminum hydroxide and the like can be used.

  After obtaining aggregated particles having a desired particle diameter in this manner, the aggregated particles are fused by heating to a temperature equal to or higher than the glass transition point of the resin, whereby desired toner particles can be obtained. Here, the toner shape can be controlled from an indeterminate shape to a spherical shape by selecting the fusion heating condition. When fused for a long time at a high temperature, the toner shape becomes closer to a true sphere.

[Image forming method]
Next, an image forming method using the developer of the present invention will be described.

  The image forming method of the present invention is formed on the surface of the latent image holding body using a latent image forming step of forming an electrostatic latent image on the surface of the latent image holding body and a developer carried on the developer carrying body. A developing process for developing the electrostatic latent image to form a toner image, a transfer process for transferring the toner image formed on the surface of the latent image holding body to the surface of the transfer target, and the image transferred to the surface of the transfer target And a fixing step for heat-fixing the toner image, wherein the developer is at least the developer containing the electrophotographic carrier of the present invention.

  As each of the above steps, a known step in the image forming method can be used.

  As the latent image holding member, for example, an electrophotographic photosensitive member and a dielectric recording member can be used. In the case of an electrophotographic photosensitive member, the surface of the electrophotographic photosensitive member is uniformly charged by a corotron charger, a contact charger or the like and then exposed to form an electrostatic latent image (latent image forming step). Next, the toner particles are adhered to the electrostatic latent image in contact with or in proximity to a developing roll having a developer layer formed on the surface, thereby forming a toner image on the electrophotographic photosensitive member (developing step). The formed toner image is transferred onto the surface of a transfer medium such as paper using a corotron charger or the like (transfer process). Further, the toner image transferred to the surface of the transfer target is heat-fixed by a fixing device, and a final toner image is formed.

  In order to prevent an offset or the like at the time of heat fixing by the fixing device, a device in which a release agent is supplied to a fixing member in the fixing device may be used.

  A material having a low surface energy can be used on the surface of a roller or belt which is a fixing member used for heat fixing in order to obtain releasability. The method of supplying the release agent is not particularly limited, and examples thereof include a pad method using a pad impregnated with a liquid release agent, a web method, a roller method, and a non-contact shower method (spray method). Among them, the web method and the roller method are preferable. These methods are advantageous in that the release agent can be supplied uniformly and it is easy to control the supply amount. In order to supply the release agent uniformly to the entire fixing member by the shower method, it is necessary to use a separate blade or the like.

  FIG. 1 is a schematic diagram showing a configuration example of an image forming apparatus for forming an image by the image forming method of the present invention. In the illustrated image forming apparatus 200, four electrophotographic photosensitive members 401 a to 401 d are disposed in parallel in the housing 400 along the intermediate transfer belt 409. The electrophotographic photoreceptors 401a to 401d form, for example, images in which the electrophotographic photoreceptor 401a is yellow, the electrophotographic photoreceptor 401b is magenta, the electrophotographic photoreceptor 401c is cyan, and the electrophotographic photoreceptor 401d is black. Is possible.

  Each of the electrophotographic photosensitive members 401a to 401d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 402a to 402d, the developing devices 404a to 404d, and the primary transfer roll 410a along the rotation direction. To 410d and cleaning blades 415a to 415d are arranged. Each of the developing devices 404a to 404d can be supplied with toner of four colors of black, yellow, magenta and cyan accommodated in the toner cartridges 405a to 405d, and the primary transfer rolls 410a to 410d are respectively intermediate transfer belts. 409 is in contact with the electrophotographic photoreceptors 401a to 401d.

  Further, an exposure device 403 is disposed at a predetermined position in the housing 400, and it becomes possible to irradiate the surfaces of the charged electrophotographic photoreceptors 401a to 401d with a light beam emitted from the exposure device 403. ing. Accordingly, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the electrophotographic photosensitive members 401a to 401d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 409 in an overlapping manner.

  Here, the charging rolls 402a to 402d contact the surface of the electrophotographic photoreceptors 401a to 401d with a conductive member (charging roll), and apply a voltage uniformly to the photoreceptor to charge the photoreceptor surface to a predetermined potential. (Charging process). In addition to the charging roll shown in this embodiment, charging by a contact charging method may be performed using a charging brush, a charging film, a charging tube, or the like. Moreover, you may charge by the non-contact system using a corotron or a scorotron.

  As the exposure apparatus 403, an optical system apparatus or the like that can expose a light source such as a semiconductor laser, an LED (light emitting diode), a liquid crystal shutter, or the like on the surfaces of the electrophotographic photosensitive members 401a to 401d can be used. Among these, when an exposure apparatus capable of exposing non-interference light is used, interference fringes between the electroconductive substrates of the electrophotographic photoreceptors 401a to 401d and the photosensitive layer can be prevented.

In the primary transfer process, a primary transfer bias having a polarity opposite to that of the toner carried on the image carrier is applied to the primary transfer rolls 410a to 410d, so that each color toner is transferred from the image carrier to the intermediate transfer belt 409. The primary transfer is performed sequentially.

  The cleaning blades 415a to 415d are for removing residual toner adhering to the surface of the electrophotographic photosensitive member after the transfer process, and the electrophotographic photosensitive member cleaned by this cleaning process is repeatedly used in the above-described image forming process. Is done. Examples of the material for the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.

  The intermediate transfer belt 409 is supported with a predetermined tension by a drive roll 406, a backup roll 408, and a tension roll 407, and can rotate without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 413 is disposed so as to contact the backup roll 408 via the intermediate transfer belt 409.

  By applying a secondary transfer bias having a reverse polarity to the toner on the intermediate transfer member to the secondary transfer roll 413, the toner is secondarily transferred from the intermediate transfer belt to the recording medium. The intermediate transfer belt 409 that has passed between the backup roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed near the drive roll 406 or a static eliminator (not shown). It is repeatedly used for the next image forming process. A tray (transfer medium tray) 411 is provided at a predetermined position in the housing 400, and the transfer medium 500 such as paper in the tray 411 is transferred to the intermediate transfer belt 409 and the secondary transfer roll by the transfer roll 412. Then, the paper is sequentially transferred between the two fixing rolls 414 that are in contact with each other and the two fixing rolls 414, and then discharged to the outside of the housing 400.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. Hereinafter, “part” means “part by weight” unless otherwise specified.

[Production of core particle 1]
Phenol 40 parts by weight, formalin 60 parts by weight, magnetite ((spherical magnetite particle powder having a volume average particle diameter of 0.25 μm (manufactured by Toda Kogyo Co., Ltd., magnetization value 64 emu / g (1 kOe), 1% by weight KBM403 treated product) 500 parts by weight) Then, 12 parts by weight of ammonia water and 60 parts by weight of ion-exchanged water were added, and while stirring, the temperature was gradually raised to 85 ° C., reacted and cured for 5 hours, cooled, filtered, washed, dried, and ta volume averaged Spherical core particles 1 having a particle size of 36 μm were obtained.

[Production of core particle 2]
Phenol 40 parts by weight, formalin 60 parts by weight, magnetite ((spherical magnetite particle powder having a volume average particle diameter of 0.40 μm (manufactured by Toda Kogyo Co., Ltd., magnetization value 64 emu / g (1 kOe), 1% by weight KBM403 treated product) 500 parts by weight) Then, 12 parts by weight of ammonia water and 60 parts by weight of ion-exchanged water were added, and while stirring, the temperature was gradually raised to 85 ° C., reacted and cured for 5 hours, cooled, filtered, washed, dried, and ta volume averaged Spherical core particles 2 having a particle size of 37 μm were obtained.

[Production of core particle 3]
Phenol 40 parts by weight, formalin 60 parts by weight, magnetite ((spherical magnetite particle powder having a volume average particle diameter of 0.10 μm (manufactured by Toda Kogyo Co., Ltd., magnetization value 64 emu / g (1 kOe), 1% by weight KBM403 treated product) 500 parts by weight) Then, 12 parts by weight of ammonia water and 60 parts by weight of ion-exchanged water were added, and while stirring, the temperature was gradually raised to 85 ° C., reacted and cured for 5 hours, cooled, filtered, washed, dried, and ta volume averaged Spherical core particles 3 having a particle size of 36 μm were obtained.

[Production of core particle 4]
40 parts by weight of phenol, 60 parts by weight of formalin, 500 parts by weight of ferrite (spherical magnetite particle powder having a volume average particle diameter of 0.40 μm (manufactured by Powdertech Co., Ltd., magnetization value 65 emu / g (1 kOe), 1% by weight KBM403 treated product)) Then, 12 parts by weight of ammonia water and 60 parts by weight of ion-exchanged water were added, and while stirring, the temperature was gradually raised to 85 ° C., reacted and cured for 5 hours, cooled, filtered, washed, dried, and ta volume averaged Spherical core particles 4 having a particle size of 37 μm were obtained.

Example 1.
[Manufacture of carrier 1]
100 parts by weight of the core particle 1 is put into a vacuum degassing type kneader, 10 parts by weight of the resin coating forming raw material solution A is added, the temperature is increased / decreased to 60 ° C./−200 mmHg, and the mixture is stirred for 15 minutes. The temperature was increased / decreased to -720 mmHg, stirred and dried for 30 minutes, returned to atmospheric pressure, heated to 180 ° C., and stirred for 30 minutes to form the first coating resin layer. Coated carrier particles 1 were obtained. Next, the entire amount of the coating resin layer forming solution B and the primary coated particles 1 are put into a vacuum degassing type kneader, and the temperature is kept at 60 ° C. and stirred for 10 minutes, and then the pressure is reduced to −720 mmHg to distill off the toluene. Thus, a carrier 1 on which a second conductive coating resin layer was formed was obtained.
<Resin coating layer forming raw material solution A>
Toluene 150 parts by weight Methyl ethyl ketone 150 parts by weight Bisphenol A type epoxy resin (EP-4100, manufactured by ADEKA) 15 parts by weight Amino-based curing agent (ADEKA HARDNER EH4602, manufactured by ADEKA) 1.5 parts by weight A coating forming raw material solution A was prepared.
<Resin coating layer forming raw material solution B>
Toluene: 100 parts by weight Styrene-methacrylate copolymer (component ratio 30:70): 2.4 parts by weight Carbon black (Regal 330; manufactured by Cabot Corporation): 0.4 parts by weight The above components and glass beads (particle size 1 mm, toluene and The same amount) was put into a sand mill manufactured by Kansai Paint Co., Ltd., and stirred at a rotational speed of 1200 rpm for 30 minutes to prepare a resin coating forming raw material B.

[Production of Cyan Toner A]
<Preparation of resin fine particle dispersion>
・ Styrene ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 296 parts by weight ・ N-butyl acrylate ・ ・ ・ ・ 104 parts by weight ・ Acrylic acid ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ ・ 6 parts by weight ・ Dodecanethiol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 10 parts by weight ・ Divinyl adipate ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 1.6 parts by weight Wako Pure Chemical Industries, Ltd.)
A mixture obtained by mixing and dissolving the above components was mixed with 12 parts of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) 8 Ion exchange with 8 parts of ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) dissolved in 610 parts of ion-exchanged water, dispersed in a flask, emulsified, and slowly mixed for 10 minutes. 50 parts of water was added and nitrogen substitution was performed at 0.1 liter / min for 20 minutes. Thereafter, the contents in the flask are heated in an oil bath until the content reaches 70 ° C. while stirring, and the emulsion polymerization is continued for 5 hours. The resin fine particle dispersion has a volume average particle size of 200 nm and a solid content concentration of 40%. (1) was prepared. When a part of the dispersion was left on an oven at 100 ° C. to remove moisture, DSC (differential scanning calorimeter) measurement was performed. The glass transition point was 53 ° C. and the weight average molecular weight was 32,000. Met.

<Preparation of colorant dispersion (C)>
C. I. Pigment Blue 15: 3: 100 parts by weight (phthalocyanine pigment: manufactured by Dainichi Seika Co., Ltd .: cyanine blue 4937)
Anionic surfactant (Neogen RK: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) ··· 10 parts by weight Ion-exchanged water ·············· 490 parts by weight The above components were mixed and dissolved, and dispersed for 10 minutes using a homogenizer (manufactured by IKA: Ultra Tarrax) to prepare a colorant dispersion (C).

<Preparation of release agent particle dispersion>
Paraffin wax (Nippon Seiwa Co., Ltd .: HNP-9) ... 100 parts by weightAnionic surfactant (Lion Co., Ltd .: Lipar 860K) ... 10 parts by weight Ion-exchanged water ... 390 parts by weight After mixing and dissolving the above components, the homogenizer (IKA: Ultrata) The release agent particle dispersion was prepared by dispersing release agent particles (paraffin wax) having a volume average particle size of 220 nm by dispersing with a pressure discharge type homogenizer.

(Manufacture of cyan toner)
・ Resin particle dispersion ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 320 parts by weight ・ Colorant dispersion (C) ・ ・ ・ ・ ・ 80 parts by weight -Release agent particle dispersion-96 parts by weight-Aluminum sulfate (Wako Pure Chemical Industries, Ltd.)-1.5 parts by weight-Ion Exchanged water: 1270 parts by weight The above components are housed in a round stainless steel flask with a temperature control jacket, and a homogenizer (manufactured by IKA, Ultra Turrax T50) ) At 5,000 rpm for 5 minutes, moved to a flask, and left standing at 25 ° C. for 20 minutes with 4 paddles. Thereafter, the mixture was heated with a mantle heater while stirring and heated at a heating rate of 1 ° C./min until the inside reached 48 ° C., and held at 48 ° C. for 20 minutes. Next, 80 parts of the resin particle dispersion was gradually added and kept at 48 ° C. for 30 minutes, and then a 1N aqueous sodium hydroxide solution was added to adjust the pH to 6.5.

  Thereafter, the temperature was raised to 95 ° C. at a rate of 1 ° C./min and held for 30 minutes. A 0.1N aqueous nitric acid solution was added to adjust the pH to 4.8, and the mixture was allowed to stand at 95 ° C. for 2 hours. Thereafter, the 1N aqueous sodium hydroxide solution was further added to adjust the pH to 6.5, and the mixture was allowed to stand at 95 ° C. for 5 hours. Thereafter, it was cooled to 30 ° C. at 5 ° C./min.

  The resulting toner particle dispersion was filtered, (A) 2,000 parts of ion-exchanged water at 35 ° C. was added to the obtained toner particles, (B) allowed to stand for 20 minutes, and (C) then filtered. After the operations from (A) to (C) were repeated 5 times, the toner particles on the filter paper were transferred to a vacuum dryer and dried at 45 ° C. and 1,000 Pa or less for 10 hours. The reason why the pressure is 1,000 Pa or less is that the above-mentioned toner particles are in a water-containing state, and in the initial stage of drying, the water freezes even at 45 ° C., and then the water sublimates. This is because is not constant. However, it was stable at 100 Pa at the end of drying. After returning the inside of the dryer to normal pressure, this was taken out to obtain toner mother particles, and 1.5 parts of silica external additive (manufactured by Nippon Aerosil Co., Ltd., RY-50) was added to 100 parts of the toner mother particles. The mixture was added and mixed with a Henschel mixer at 3,000 rpm for 3 minutes to obtain cyan toner A.

  The obtained cyan toner A had a D50v of 5.8 μm, a GSDp of 1.22, an acid value of 25 mgKOH / g, and a glass transition temperature of 53 ° C. The sphericity was 0.98.

[Preparation of Developer 1]
100 parts by weight of carrier 1 and 8 parts by weight of cyan toner A as a toner were mixed with a V blender and sieved to prepare developer 1.

Example 2
[Manufacture of carrier 2]
The manufacturing method of the carrier 1 of Example 1 was changed except that the amount of the resin coating layer forming raw material solution A added to the core particles 1 used in the carrier 1 of Example 1 was changed to 20 parts by weight and the thickness of the resin film was changed. As a result, Carrier 2 was obtained.

[Preparation of Developer 2]
Developer 2 was obtained according to the method for preparing Developer 1 except that Carrier 1 was replaced with Carrier 2 in the preparation of Developer 1.

Example 3
[Manufacture of carrier 3]
The manufacturing method of the carrier 1 of Example 1 was changed except that the amount of the resin coating layer forming raw material solution A added to the core particles 1 used in the carrier 1 of Example 1 was changed to 35 parts by weight and the thickness of the resin film was changed. As a result, I got Carrier 3.

[Preparation of Developer 3]
Developer 3 was obtained according to the method for preparing Developer 1 except that Carrier 1 was replaced with Carrier 3 in the preparation of Developer 1 above.

Example 4
[Manufacture of carrier 4]
The manufacturing method of the carrier 1 of Example 1 was changed except that the amount of the resin coating layer forming raw material solution A added to the core particles 1 used in the carrier 1 of Example 1 was changed to 50 parts by weight and the thickness of the resin film was changed. As a result, Carrier 4 was obtained.

[Preparation of Developer 4]
Developer 4 was obtained according to the method for preparing Developer 1 except that Carrier 1 was replaced with Carrier 4 in the preparation of Developer 1 above.

Example 5 FIG.
[Manufacture of carrier 5]
The core particle 1 used in the carrier 1 of Example 1 is replaced with the core particle 2, the addition amount of the resin coating layer forming raw material solution A is changed to 10 parts by weight, and the thickness of the resin coating is changed. In accordance with the manufacturing method of carrier 1, carrier 5 was obtained.

[Preparation of Developer 5]
A developer 5 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 5 in the preparation of the developer 1.

Example 6
[Manufacture of carrier 6]
The manufacturing method of the carrier 5 of Example 5 was changed except that the amount of the resin coating layer forming raw material solution A added to the core particles 2 used in the carrier 5 of Example 5 was changed to 25 parts by weight and the thickness of the resin film was changed. As a result, career 6 was obtained.

[Preparation of Developer 6]
A developer 6 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 6 in the preparation of the developer 1.

Example 7
[Manufacture of carrier 7]
The manufacturing method of the carrier 5 of Example 5 was changed except that the amount of the resin coating layer forming raw material solution A added to the core particles 2 used in the carrier 5 of Example 5 was changed to 40 parts by weight and the thickness of the resin film was changed. As a result, I got Carrier 7.

[Preparation of Developer 7]
Developer 7 was obtained according to the method for preparing Developer 1 except that Carrier 1 was replaced with Carrier 7 in the preparation of Developer 1 above.

Example 8 FIG.
[Manufacture of carrier 8]
The manufacturing method of the carrier 5 of Example 5 was changed except that the amount of the resin coating layer forming raw material solution A added to the core particles 2 used in the carrier 5 of Example 5 was changed to 70 parts by weight and the thickness of the resin film was changed. As a result, Carrier 8 was obtained.

[Preparation of developer 8]
A developer 8 was obtained in accordance with the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 8 in the preparation of the developer 1.

Example 9
[Manufacture of carrier 9]
The core particle 1 used in the carrier 1 of Example 1 was replaced with the core particle 3, the addition amount of the resin coating layer forming raw material solution A was changed to 5 parts by weight, and the thickness of the resin coating was changed. In accordance with the manufacturing method of carrier 1, carrier 9 was obtained.

[Preparation of Developer 9]
A developer 9 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 9 in the preparation of the developer 1.

Example 10
[Manufacture of carrier 10]
The manufacturing method of the carrier 9 of Example 9 was changed except that the amount of the resin coating layer forming raw material solution A added to the core particles 3 used in the carrier 9 of Example 9 was changed to 10 parts by weight and the thickness of the resin film was changed. As a result, Carrier 10 was obtained.

[Preparation of Developer 10]
A developer 10 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 10 in the preparation of the developer 1.

Example 11
[Manufacture of carrier 11]
The method for producing the carrier 9 of Example 9 is the same as that of Example 9 except that the amount of the resin coating layer forming raw material solution A added to the core particles 3 used in the carrier 9 of Example 9 is changed to 30 parts by weight and the thickness of the resin film is changed. As a result, Carrier 11 was obtained.

[Preparation of Developer 11]
A developer 11 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 11 in the preparation of the developer 1.

Example 12 FIG.
[Manufacture of carrier 12]
A carrier 12 was obtained according to the manufacturing method of the carrier 1 of Example 1, except that the core particle 1 used in the carrier 1 of Example 1 was replaced with the core particle 4.

[Preparation of Developer 12]
A developer 12 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 12 in the preparation of the developer 1.

Example 13
[Manufacture of carrier 13]
The manufacturing method of the carrier 12 of Example 12 was changed except that the amount of the resin coating layer forming raw material solution A added to the core particles 4 used in the carrier 12 of Example 12 was changed to 20 parts by weight and the thickness of the resin film was changed. As a result, Carrier 13 was obtained.

[Preparation of Developer 13]
A developer 13 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 13 in the preparation of the developer 1.

Example 14 FIG.
[Manufacture of carrier 14]
The manufacturing method of the carrier 12 of Example 12 was changed except that the amount of the resin coating layer forming raw material solution A added to the core particles 4 used in the carrier 12 of Example 12 was changed to 40 parts by weight and the thickness of the resin film was changed. As a result, career 14 was obtained.

[Preparation of Developer 14]
A developer 14 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 14 in the preparation of the developer 1.

Example 15.
[Manufacture of carrier 15]
A carrier 15 was obtained according to Example 1 except that the core particle 1 was used and the resin coating layer forming raw material solution A was changed to the resin coating layer forming raw material solution C.
<Resin coating layer forming raw material solution C>
Toluene: 100 parts by weight Straight resol (PR-51107, Sumitomo Bakelite Co., Ltd.): 25 parts by weight The above components were stirred with a stirrer to prepare a resin coating forming raw material solution C.

[Preparation of Developer 15]
100 parts by weight of carrier 15 and 8 parts by weight of cyan toner A as a toner were mixed with a V blender, and sieved to prepare developer 15.

Comparative Example 1
[Manufacture of carrier 16]
The core particle 1 used in the carrier 1 of Example 1 was replaced with the core particle 2, the addition amount of the resin coating layer forming raw material solution A was changed to 30 parts by weight, and the thickness of the resin film was changed, except that the thickness of the resin film was changed. In accordance with the manufacturing method of carrier 1, carrier 16 was obtained.

[Preparation of Developer 16]
A developer 16 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 16 in the preparation of the developer 1.

Comparative Example 2
[Manufacture of carrier 17]
The core particle 1 used in the carrier 1 of Example 1 was replaced with the core particle 3, the addition amount of the resin coating layer forming raw material solution A was changed to 30 parts by weight, and the thickness of the resin film was changed, except that the thickness of the resin film was changed. In accordance with the manufacturing method of carrier 1, carrier 17 was obtained.

[Preparation of Developer 17]
A developer 17 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 17 in the preparation of the developer 1.

Comparative Example 3
[Manufacture of carrier 18]
The core particle 1 used in the carrier 1 of Example 1 was replaced with the core particle 2, the addition amount of the resin coating layer forming raw material solution A was changed to 100 parts by weight, and the thickness of the resin film was changed. According to the manufacturing method of carrier 1, carrier 18 was obtained.

[Preparation of Developer 18]
A developer 18 was obtained in accordance with the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 17 in the preparation of the developer 1.

Comparative Example 4
[Manufacture of carrier 19]
According to the manufacturing method of the carrier 1 of Example 1, except that the amount of the resin coating layer forming raw material solution A was changed to 100 parts by weight and the thickness of the resin film was changed. 19 was obtained.

[Preparation of Developer 19]
A developer 19 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 19 in the preparation of the developer 1.

Comparative Example 5
[Manufacture of carrier 20]
The core particle 1 used in the carrier 1 of Example 1 was replaced with the core particle 3, the addition amount of the resin coating layer forming raw material solution A was changed to 100 parts by weight, and the thickness of the resin film was changed, except that the thickness of the resin film was changed. In accordance with the manufacturing method of carrier 1, carrier 20 was obtained.

[Preparation of Developer 20]
A developer 20 was obtained according to the method for preparing the developer 1 except that the carrier 1 was replaced with the carrier 20 in the preparation of the developer 1.

<Evaluation method>
[Rear end blank evaluation]
Using the above-mentioned Docu Center Color 400 remodeling machine (manufactured by Fuji Xerox Co., Ltd.) shown in FIG. 1, as shown in FIG. 2, a halfton having a size of 5 cm × 5 cm and a toner loading of 3 g / cm ² on A4 paper. An image was output. Evaluation was performed visually and with a magnifying glass of 25 times. The evaluation criteria are as follows.
(Double-circle): The state where a white spot in the rear end cannot be seen with both the loupe and the visual inspection.
○: The rear end white spot is seen with the loupe, but it cannot be visually confirmed.
X: State in which the trailing edge white spot is visually observed.

[Evaluation of density boundary white spot]
Using the above-mentioned Docu Center Color 400 remodeling machine (manufactured by Fuji Xerox Co., Ltd.) shown in FIG. 1, as shown in FIG. 3, a solid image having a toner loading of 6 g / cm ² of 5 cm × 2 cm is adjacent to A4 paper. A 2 cm × 2 cm half-toned image with a toner loading of 1.2 g / cm ² was output. Evaluation was performed visually and with a magnifying glass of 25 times. The evaluation criteria are as follows.
A: State where white spots are not seen at the density boundary part both in the loupe and visually.
○: In the loupe, white spots are seen at the density boundary, but cannot be confirmed visually.
X: A state in which white spots are seen at the density boundary portion visually.

[Evaluation of carrier adhesion]
Using the Docu Center Color 400 modified machine (manufactured by Fuji Xerox Co., Ltd.) shown in FIG. 1 described above, the carrier attached on the photosensitive member was visually evaluated according to the following criteria. Specific evaluation criteria are as follows.
○: No carrier adhesion on the photoreceptor.
Δ: There is some carrier adhesion on the photoreceptor, but there is no problem in actual use.
X: Carrier adhesion on the photoreceptor is conspicuous.

  According to the print test, the carrier and developer of the present invention have good transportability and can provide high image quality in any environment.

  The carrier for developing an electrostatic charge image, the developer for the electrostatic charge image, and the image forming method using them are preferably used particularly for a method for visualizing image information through an electrostatic latent image such as electrophotography. it can.

It is the schematic which shows the structural example of the image forming apparatus for forming simultaneously a visible image with an invisible image with the image forming method of this invention. It is a figure explaining back end white spot evaluation. It is a figure explaining density | concentration boundary part white-out evaluation.

Explanation of symbols

  200 Image forming apparatus, 401a to 401d electrophotographic photosensitive member, 400 housing, 401a to 401d electrophotographic photosensitive member, 402a to 402d charging roll, 403 exposure device, 404a to 404d developing device, 405a to 405d toner cartridge, 409 intermediate transfer belt 410a to 410d Primary transfer roll, 411 tray (transfer medium tray), 413 Secondary transfer roll, 414 Fixing roll, 415a to 415d, 416 Cleaning blade, 500 Transfer medium.

Claims (3)

A static resin is formed in which a first resin film made of resin is formed on the surface of magnetic particles containing magnetic powder in a resin, and a second conductive resin film made of conductive resin is formed on the surface of the first resin film. A carrier for developing an electrostatic latent image,
When the saturation magnetization of the electrostatic latent image developing carrier is σs and the true specific gravity of the electrostatic latent image developing carrier is D,
175 emu / cm ³ ≦ σs × D ≦ 250 emu / cm ³
The electrostatic latent image developing carrier is characterized in that the thickness of the second conductive resin film is larger than the thickness of the first resin film. The electrostatic latent image developing carrier according to claim 1,
A carrier for developing an electrostatic latent image, wherein the thickness of the first resin film is smaller than the volume average particle diameter of the magnetic powder particles.   An electrostatic latent image developing developer comprising: the electrostatic latent image developing carrier according to claim 1 or 2; and toner particles.