JP2008083098A - Carrier for electrostatic latent image development, developer for electrostatic latent image development, developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer for electrostatic latent image development which stabilizes developer conveyability and suppresses density unevenness over a long period of time even in long-term use and high-speed operation, a carrier for electrostatic latent image development for use in the developer, and a process cartridge and an image forming apparatus using the developer for electrostatic latent image development. <P>SOLUTION: The carrier for electrostatic latent image development has a ten-point average roughness Rz of its surface of 2-2.5, a standard deviation of the ten-point average roughness Rz of ≤0.3 and an average circularity of ≥0.98. The developer for electrostatic latent image development includes the carrier for electrostatic latent image development. The process cartridge and the image forming apparatus use the developer for electrostatic latent image development. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developer for developing an electrostatic latent image used for electrophotography and electrostatic recording, a carrier for developing an electrostatic latent image used for the developer, and a developing device using the developer for developing an electrostatic latent image. And an image forming apparatus.

  In recent years, demands for space saving and high speed of image forming apparatuses are increasing. As a result, the size of image forming apparatuses has been reduced from the viewpoint of space saving, and the amount of developer has been reduced. As a result, the stress on the developer has increased compared to conventional image forming apparatuses. This is the current situation. In contrast, attempts have been made to reduce the carrier diameter. However, when the carrier diameter is reduced, the fluidity of the carrier and the developer is lowered, so that the stress in the developing machine increases. This phenomenon is particularly remarkable in a small-sized image forming apparatus that has been increased in speed, and the developer is packed in the developing machine, particularly in the developer layer regulating member. The developer packed in this way not only promotes deterioration but also wears the surface of the developer holder. Therefore, the conveyance amount is reduced. When the transport amount is reduced in this way, the developing electric field applied to the developer in the developing area is increased, so that a problem of so-called carrier adhesion that the carrier moves to the electrostatic latent image holding member is likely to occur.

  Various proposals have been made for this. For example, a carrier having a height difference of 5 to 20 nm from a concave portion adjacent to the carrier convex portion (see, for example, Patent Document 1), the magnetization and carrier resistance of the scattered carrier are controlled, and the average height difference of the carrier surface unevenness is 0.1. -2.0 μm (for example, see Patent Document 2), carrier resistance, specific gravity and fluidity are controlled, and the surface roughness of the developer carrier using a specific resin is 0.2 μm ≦ Ra ≦ 5.0 μm. 10 μm ≦ Sm ≦ 80 μm, 0.05 ≦ Ra / Sm ≦ 0.5 (for example, refer to Patent Document 3), two magnetic poles provided in the developing unit (for example, refer to Patent Document 4), etc. Each has been made.

Further, the specific resistance of the magnetic carrier particles is 5.0 × 10 ¹³ Ωcm or more when 25 V to 500 V is applied, the magnetization intensity at 1 kilo Oersted is 40 to 250 emu / cm ³ , and the true specific gravity is 3.0 to 4.9 g / cm ³ , Fe (II) content with respect to the eluted iron element concentration on the surface of the magnetic carrier particles is 0.001 to 5.0% by weight, and developer magnetic formed on the developer holder There has been proposed an image forming method (see, for example, Patent Documents 5 and 6) in which development is performed while applying an alternating electric field by bringing a brush into contact with the electrostatic latent image holding member.

Further, the surface of the developer carrier, a developing device having a groove extending in a plurality of longitudinally product is 0.05 mm ² or more 0.1 mm ² or less between the depth average H and the gap G (for example, Patent Document 7 Have been proposed).
JP 2002-169341 A JP 2004-286879 A JP 2004-212519 A JP 2005-195994 A JP 2005-115201 A JP-A-2005-99072 JP 2005-24611 A

  The present invention has been made in view of the above-described problems, and its object is to stabilize developer transportability over a long period of time even during long-term use and high-speed operation, and to suppress density unevenness and carrier adhesion due to poor developer transport. It is an object of the present invention to provide an electrostatic latent image developing developer, an electrostatic latent image developing carrier used for the developer, a developing device and an image forming apparatus using the electrostatic latent image developing developer.

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 present invention
<1> The ten-point average roughness Rz of the surface is 2 or more and 2.5 or less, the standard deviation of the ten-point average roughness Rz is 0.3 or less, and the average circularity is 0.98. The electrostatic latent image developing carrier is as described above.

<2> An electrostatic latent image developing developer comprising a toner and a carrier, wherein the electrostatic latent image developing carrier according to <1> is used as the carrier.
<3> The electrostatic latent image according to <2>, wherein the toner contains particles having a volume average particle diameter of 50 to 200 nm as an external additive and has a shape factor SF1 of 110 to 140. It is a developer for image development.

<4> A developer holding body that is provided to face the electrostatic latent image holding body and supplies the developer to the electrostatic latent image holding body, and a developer storage chamber that stores the developer. A developing device comprising: the developer for developing an electrostatic charge image according to <2> or <3>.
<5> The outer peripheral surface of the developer holder has a plurality of grooves extending in the longitudinal direction of the developer holder, and the width of the plurality of grooves is 2 to 6 times the volume average particle diameter of the carrier. The developing device according to <4>, wherein

<6> An electrostatic latent image holding member, a charging unit for charging the electrostatic latent image holding member, and exposing the charged electrostatic latent image holding member to electrostatically charge on the electrostatic latent image holding member. An exposure unit that forms a latent image; a developing unit that develops the electrostatic latent image on the electrostatic latent image holding member to form a toner image using the developer held on the developer holding member; A transfer unit that transfers the toner image from the electrostatic latent image holding member to the recording material; and a cleaning unit that removes residual toner on the surface of the electrostatic latent image holding member after the transfer. > Or <3>. An image forming apparatus comprising the developer for developing an electrostatic image according to <3>.
<7> The outer peripheral surface of the developer holder has a plurality of grooves extending in the longitudinal direction of the developer holder, and the width of the plurality of grooves is 2 to 6 times the volume average particle diameter of the carrier. <6> The image forming apparatus according to <6>.

  According to the present invention, a developer for electrostatic latent image development that stabilizes developer transportability over a long period of time even during long-term use and high-speed operation, and suppresses density unevenness and carrier adhesion due to developer transport failure, and the developer. It is possible to provide an electrostatic latent image developing carrier to be used, a developing device and an image forming apparatus using the electrostatic latent image developing developer.

  The electrostatic latent image developing carrier of the present invention (hereinafter sometimes referred to as “the carrier of the present invention”) has a surface ten-point average roughness Rz of 2 or more and 2.5 or less. The standard deviation of the average roughness Rz is 0.3 or less, and the average circularity is 0.98 or more.

  Until now, in order to obtain the concentration stability, the weight reduction and the high fluidity of the carrier have been studied. However, such a lightened or highly fluidized carrier has good packing properties, so it tends to stay behind the layer regulating member that regulates the developer transport amount of the developer holder, and the retained developer is developed. The frictional force with the surface of the agent holder is increased. Therefore, the surface of the developer holding member and the carrier surface are worn by frictional force. Wear on the surface of the developer holding member causes a decrease in developer conveyance, and as a result, density unevenness and carrier adhesion are induced.

In order to solve these problems, (1) a developer having good fluidity and suitable packing properties, and (2) a developer holder that has little influence even when the surface is worn can be used. .
In order to impart an appropriate packing property with conventional spherical carriers, it has been considered to make the unevenness of the carrier surface uniform. When the size of the convex portions and concave portions on the carrier surface is uneven, the carrier particles are stacked on the large convex portions and concave portions. However, when the carrier surface is smooth, the carrier is easily packed behind the layer regulating member, and slips between the carriers to form a finely packed structure. In such a case, the developer packing force is larger than the developer carrying force, and thus poor conveyance or uneven conveyance occurs. As described above, when the carrier surface is uneven or too smooth, the developer holding member and the frictional force are increased. That is, poor developer conveyance or uneven conveyance occurs, and density unevenness occurs. Further, when the stack and the frictional force are large, detachment and wear of the resin coating layer on the carrier surface are promoted, and the resistance of the carrier and the developer is lowered, so that the carrier easily adheres.

  The carrier of the present invention has a specific average circularity, and further, by controlling the 10-point average roughness Rz of the carrier surface and its standard deviation, it is possible to improve the stacking property and slip between the carriers. The developer flow is improved and the residence time is relaxed, so that the wear on the surface of the carrier and the developer holding body can be suppressed and stable transportability can be obtained.

  The ten-point average roughness Rz of the carrier of the present invention is required to be 2.0 or more and 2.5 or less, preferably 2.0 or more and 2.4 or less, and 2.0 or more and 2.3 or less. It is more preferable that If the ten-point average roughness Rz is less than 2.0, the carrier surface becomes relatively smooth, so that it is easy to accumulate behind the layer regulating member, and the transport amount to the developer carrying member is reduced. Carrier adhesion occurs. Further, if the ten-point average roughness Rz exceeds 2.5, it means that the carrier surface has large irregularities, the carriers are stacked behind the layer regulating member, the developer carrier surface is worn, and the transport amount is It becomes unstable.

  In addition, the standard deviation of the ten-point average roughness Rz of the carrier of the present invention must be 0.30 or less, preferably 0.25 or less, and more preferably 0.20 or less. When the standard deviation of the ten-point average roughness Rz exceeds 0.3, it means that the carrier surface is non-uniform, and the carrier is likely to be stacked behind the layer regulating member.

  Here, the ten-point average roughness Rz of the carrier of the present invention was determined as follows. Using a laser microscope (ultra-deep color 3D shape measurement microscope (VK-9500): manufactured by Keyence Corporation), observation was performed in a field of view 300 times the particle surface with respect to one carrier particle. The heights of convex portions and concave portions having a measurement distance of 10 μm were measured at seven locations at intervals of 3 μm with reference to the center of the visual field. The average value was measured from the measured values of the measured unevenness and was defined as Rz. Moreover, the smoothing process was implemented by the cut-off value 0.08mm in the case of a measurement. In addition, Rz of this invention selected arbitrary 50 carriers, calculated Rz of each carrier, and made the average value Rz. Further, the standard deviation is a standard deviation obtained from 50 Rz values of each carrier.

On the other hand, the carrier of the present invention must have an average circularity of 0.98 or more, and preferably 0.985 or more. When the average circularity is less than 0.98, not only the fluidity is lowered, but also the resin coating layer on the convex portion of the carrier surface is easily detached due to in-machine stress. Here, the average circularity of the carrier of the present invention was measured by the following method using a carrier in a residue obtained by adding and stirring 200 mg of carrier to 30 ml of an ethylene glycol aqueous solution and removing the supernatant aqueous solution as a measurement sample. For measurement, FPIA-3000 (manufactured by Sysmex Corporation) was used, and image analysis was performed on at least 5,000 or more captured carrier particles, and the average circularity was obtained by statistical processing. Here, each circularity was calculated | required based on the following Formula (2).
Formula (2) Circularity = circle equivalent diameter perimeter / perimeter = [2 × (A × π) ^1/2 ] / PM
(In the above formula, A represents the projected area of the carrier particles, and PM represents the perimeter of the carrier particles.)
The measurement was performed in the HPF mode (high resolution mode) and the dilution factor of 10 times. In the data analysis, the number particle size analysis range was 3 to 80 μm and the circularity analysis range was 0.85 to 1.0 for the purpose of removing measurement noise.

  The present invention has a ten-point average roughness Rz of 2 or more and 2.5 or less, a standard deviation of the ten-point average roughness Rz of 0.3 or less, and an average circularity of 0.98 or more. First, a first coating layer that covers the core material is formed on the surface of the core material, and then a second coating layer that covers the core material on which the first coating layer is formed is formed. Thus, it can be preferably manufactured. Further, a core material whose surface is highly controlled, for example, ferrite or the like, can be manufactured by using a core material in which the crystal size is uniform and the particle size distribution and dispersion of the magnetic particles are controlled if the particle size is uniformly dispersed. Moreover, it is also possible to manufacture by controlling the coating layer.

  The core material used in the carrier of the invention is not particularly limited, and magnetic particles such as iron, steel, nickel and cobalt, or magnetic oxides such as ferrite and magnetite, and magnetic particles in which magnetic fine particles are dispersed in a resin. Examples thereof include dispersed particles and glass beads. Among these, magnetite and magnetic particle dispersed particles are preferable because the shape of the carrier surface can be easily controlled. Moreover, as a volume average particle diameter of these core materials, it is preferable that it is 10-150 micrometers, More preferably, it is 30-100 micrometers.

  Examples of the component constituting the first coating layer include urea-formaldehyde resin, melamine resin, phenol resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Melamine resin, phenol resin, benzoguanamine resin, urea Resins and polyamide resins are preferred. The thickness of the first coating layer is preferably from 0.01 to 0.50 μm, more preferably from 0.01 to 0.20 μm, from the viewpoint that the shape of the carrier surface can be easily controlled.

  As the component constituting the second coating layer, a known resin can be used as long as it is used as a resin layer material for a carrier, and two or more kinds of resins may be blended and used. The resin constituting the resin layer is roughly classified into a charge imparting resin for imparting chargeability to the toner and a resin having a low surface energy used for preventing the toner component from being transferred to the carrier.

Here, examples of the charge imparting resin for imparting negative chargeability to the toner include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Further, polystyrene resins such as polyvinyl and polyvinylidene resins, acrylic resins, polymethyl methacrylate resins, styrene acrylic copolymer resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, ethyl cellulose resins And the like.
Examples of the charge imparting resin for imparting positive chargeability to the toner include polystyrene resins, halogenated olefin resins such as polyvinyl chloride, polyester resins such as polyethylene terephthalate resins and polybutylene terephthalate resins, and polycarbonate resins. Can be mentioned.

  Examples of the resin having a low surface energy used for preventing the transfer of the toner component to the carrier include polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, fluororesin. Fluoroterpolymers such as copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, And silicone resin.

  In addition, conductive fine particles may be added to the second coating layer for the purpose of adjusting electric resistance. Examples of the conductive fine particles include metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide. These conductive powders preferably have an average particle size of 1 μm or less. Furthermore, a plurality of conductive resins and the like can be used in combination as necessary.

Furthermore, the second coating layer may contain resin fine particles for the purpose of charge control. As the resin constituting the resin fine particles, a thermoplastic resin or a thermosetting resin can be used.
In the case of thermoplastic resins, polyolefin resins, such as polyethylene, polypropylene; polyvinyl and polyvinylidene resins, such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl Ether and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin composed of an organosiloxane bond or a modified product thereof; fluororesin such as polytetrafluoroethylene, polyvinyl fluoride, polyfluoride And vinylidene chloride, polychlorotrifluoroethylene; polyester; polycarbonate and the like.

  Examples of thermosetting resins include phenol resins; amino resins such as urea-formaldehyde resins, melamine resins, benzoguanamine resins, urea resins, polyamide resins; epoxy resins and the like.

The particle diameter of the resin fine particles is preferably 0.1 to 1.5 μm. If the particle size is less than 0.1 μm, the dispersibility is poor and the particles are aggregated in the resin layer, the exposure rate of the core particle surface becomes unstable, and it may be difficult to keep the charging characteristics stable. Further, since the film strength of the resin layer is reduced at the aggregate interface, the resin layer may be easily broken.
On the other hand, when the particle size of the resin fine particles exceeds 1.5 μm, the resin fine particles are likely to be detached from the resin layer, and the charge imparting function may not be exhibited. Moreover, the strength of the resin layer may be reduced depending on the particle size.

  The average film thickness of the second coating layer is preferably 0.1 μm to 5 μm, more preferably 0.3 μm to 3 μm, and still more preferably 0.3 μm to 2 μm. If the average film thickness of the second coating layer is less than 0.1 μm, it may be difficult to uniformly coat the core particles, and the film strength of the resin coating layer may be weakened. In addition to agglomeration and deterioration in productivity, the resin coating layer may not be uniform and the resin coating layer may be easily detached from the carrier.

-Carrier manufacturing method-
The production method of the carrier of the present invention is not particularly limited, and a conventionally known carrier production method can be used, but the following production methods are preferred.
Formation of the first coating layer for coating the core material is performed by dipping using the coating layer solution, spraying method for spraying on the surface of the core material, flow for spraying the coating layer solution while the core material is suspended by flowing air Examples include the floor method and the kneader coater method. The first coating layer is preferably a resin that does not dissolve in the second coating layer forming solution, and more preferably a thermosetting resin.

Next, the formation of the second coating layer covering the core material on which the first coating layer has been formed is performed by the second coating layer forming solution (in the solvent, the matrix resin for forming the second coating layer). In addition, the core material on which the first coating layer is formed is used in the second coating layer forming solution. Dipping method, spraying the second coating layer forming solution onto the surface of the core material on which the first coating layer is formed, floating the core material on which the first coating layer is formed with flowing air In the fluidized bed method in which the second coating layer forming solution is sprayed in a state of being mixed, the core material on which the first coating layer is formed and the second coating layer forming solution are mixed in a kneader coater, and then the solvent is added. The kneader coater method to remove is mentioned, but it is especially limited to those using a solution. No. For example, depending on the type of the core particles used for the production of the carrier, a powder coating method in which the core particles and the resin powder are heated and mixed together can be appropriately employed.
Further, the solvent used in the second coating layer forming solution for forming the second coating layer is not particularly limited as long as it dissolves the matrix resin. For example, xylene, toluene Aromatic hydrocarbons such as acetone, ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran and dioxane, halides such as chloroform and carbon tetrachloride, and the like can be used.

(Developer for developing electrostatic latent images)
The developer for developing an electrostatic latent image of the present invention (hereinafter sometimes referred to as “developer of the present invention”) includes a toner and a carrier, and the carrier of the present invention is used as the carrier. To do.
Here, the mixing ratio (mass ratio) of the toner and the carrier is preferably in the range of 1: 100 to 20: 100, and more preferably in the range of 3: 100 to 15: 100. preferable.

  As the toner used in the present invention, known toners can be used, and the production method thereof is not particularly limited. However, the toner contains particles having a volume average particle size of 50 to 200 nm as an external additive, and has a shape factor. SF1 is preferably 110 to 140. The toner having the shape factor SF1 in the range of 110 to 140 has no sharp portion or is not sharp even if it exists, and has a shape with rounded corners. In the case of such a toner, even if it collides with the photoconductor, the contact area is wider than that of the kneaded and pulverized toner, so that the pressure applied to the external additive between the surface of the photoconductor and the toner is reduced, and the photoconductor It is possible to make it difficult to scratch the surface.

  On the other hand, by containing particles having a volume average particle size of 50 to 200 nm as an external additive, the external additive passes through the cleaning blade, thereby reducing the adhesion between the toner and the photoreceptor, and reducing the frictional force. As a result, the contact width between the cleaning blade and the photosensitive member is narrowed, and toner entry and filming can be suppressed. As a result, even when a toner having a shape factor SF1 of 110 to 140 is used, it is possible to improve the cleaning property of the photoreceptor. Further, by using the toner together with the carrier of the present invention described above, the fluidity of the developer is not impaired.

  The external additive contained in the toner preferably has a volume average particle size of 50 to 200 nm, more preferably 50 to 150 nm, and still more preferably 50 to 120 nm. If the volume average particle size of the external additive is less than 50 nm, the external additive particles are likely to aggregate, and it may be difficult to uniformly disperse the toner surface. Further, it may be easily embedded in the toner surface due to stress in the developing machine and the pressure with the photosensitive member, and the cleaning property may be deteriorated. On the other hand, when the thickness exceeds 200 nm, the dispersion on the toner surface is improved, but the toner surface is improved. Adhesiveness is poor and it is easy to detach, which may damage the surface of the photoreceptor. The volume average particle size of the external additive can be measured using a laser diffraction / scattering particle size distribution measuring device (HORIBA LA-910).

  Further, the content of the external additive in the toner is preferably 0.1 to 10.0% by mass, and more preferably 0.3 to 5.0% by mass. If the content of the external additive in the toner is less than 0.1% by mass, the abundance of the external additive in the toner particles is small, and it may be difficult to improve the cleaning property. In some cases, aggregation of the external additive occurs on the toner surface and is easily detached from the toner, which may easily damage the surface of the photoreceptor.

On the other hand, the shape factor SF1 of the toner used in the present invention is preferably 110 to 140, and more preferably 115 to 130. When the shape factor SF1 is less than 110, cleaning failure may occur. When the shape factor SF1 exceeds 140, the transfer efficiency may decrease. Here, the shape factor SF1 of the toner is obtained by the following procedure. The toner shape factor SF1 is calculated by taking an optical microscope image of toner spread on a slide glass into a Luzex image analyzer through a video camera, measuring the maximum length of 50 or more toners, and the projected area of the toner. It calculated by Formula (3). In the calculation, the average value of 50 or more toners was obtained.
Formula (3) SF1 = ((absolute maximum length of toner diameter) ² / projection area of toner) × (π / 4) × 100

  The method for producing the toner used in the present invention is not particularly limited, and known ones can be used. For example, in addition to a binder resin, a colorant, and a release agent, a charge control agent and the like are kneaded and pulverized as necessary. , A kneading and pulverizing method for classifying, a method for changing the shape of particles obtained by the kneading and pulverizing method by mechanical impact force or thermal energy, and a dispersion formed by emulsion polymerization of a polymerizable monomer of a binder resin Emulsion polymerization aggregation method to obtain toner particles by mixing the liquid with a colorant, a release agent or, if necessary, a dispersion of a charge control agent, etc. Suspension polymerization method in which a monomer, a colorant, a release agent and, if necessary, a solution such as a charge control agent are suspended in an aqueous solvent for polymerization, a binder resin and a colorant, a release agent, if necessary A solution suspension method in which a solution such as a charge control agent is suspended in an aqueous solvent and granulated can be used. In addition, a known method such as a production method in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to give a core-shell structure can be used, but from the viewpoint of shape control and particle size distribution control Suspension polymerization method, emulsion polymerization aggregation method, and dissolution suspension method, which are produced from an aqueous solvent, are preferred, and emulsion polymerization aggregation method is particularly preferred.

  In the emulsion polymerization aggregation method, a resin particle dispersion in which resin particles having a particle diameter of 1 μm or less are dispersed, a colorant dispersion in which a colorant is dispersed, and the like are mixed to aggregate the resin particles and the colorant into a toner particle diameter. (Hereinafter, sometimes referred to as “aggregation step”), a step of heating the resin particles to a temperature equal to or higher than the glass transition point of the resin particles to fuse the aggregates to form toner particles (hereinafter, sometimes referred to as “fusion step”). including.

  In the aggregation step, the resin particle dispersion, the colorant dispersion, and, if necessary, the particles in the release agent dispersion are aggregated to form aggregated particles. The agglomerated particles are formed by heteroaggregation or the like. For the purpose of stabilizing the agglomerated particles and controlling the particle size / particle size distribution, the ionic surfactant having a polarity different from that of the agglomerated particles, or a monovalent or more monovalent metal salt or the like is used. A charged compound is added.

  In the fusion step, the resin particles in the aggregated particles are melted at a temperature condition equal to or higher than the glass transition point, and the aggregated particles change from an indeterminate shape to a spherical shape. At this time, the shape factor SF1 of the agglomerated particles is 150 or more. However, the shape factor SF1 can be controlled by stopping the heating of the toner when the desired shape factor is reached. Thereafter, the agglomerates are separated from the aqueous medium, and washed and dried as necessary to form toner particles.

  Further, as a method for producing the electrostatic latent image developing toner used in the present invention, a suspension polymerization method can also be preferably used. In the suspension polymerization method, colorant particles, release agent particles and the like are suspended in an aqueous medium to which a dispersion stabilizer and the like are added together with a polymerizable monomer as required, and a desired particle size and particle size distribution are obtained. In this method, the polymerizable monomer is polymerized by means of heating or the like, and then the polymer is separated from the aqueous medium, and washed and dried as necessary to form toner particles.

The toner used in the present invention contains a binder resin and a colorant, and preferably further contains a release agent. If necessary, silica or a charge control agent may be used. The volume average particle diameter of the toner is preferably 2 to 12 μm, and more preferably 3 to 9 μm.
The volume average particle size of the toner is obtained as a particle size that is 50% cumulative by drawing a cumulative distribution from the small diameter side with respect to the volume particle size distribution using LS-Particle-Size-Analyzer (COULTER). .

  As the binder resin used, styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate, Α-methylene aliphatic monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymers and copolymers such as vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone. In particular, typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-anhydride maleate. Examples thereof include acid copolymers, polyethylene, and polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  In addition, as colorants, magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, Lamp Black, Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be cited as a representative example.

  Typical examples of the releasing agent include low molecular polyethylene, low molecular polypropylene, Fischer tropic wax, montan wax, carnauba wax, rice wax, and candelilla wax.

In addition, a charge control agent may be added to the toner as necessary. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination.
The toner used in the present invention may be a magnetic toner containing a magnetic material or a non-magnetic toner not containing a magnetic material.

  On the other hand, particles having a volume average particle diameter of 50 to 200 nm as the external additive include silica, titanium oxide, metatitanic acid, aluminum oxide, magnesium oxide, alumina, barium titanate, magnesium titanate, calcium titanate, titanium. Examples thereof include fine particles of strontium acid, zinc oxide, chromium oxide, antimony trioxide, magnesium oxide, zirconium oxide and the like. Among these, it is preferable to use one selected from silica, titanium oxide, and metatitanic acid from the viewpoint of precise charge control of the toner to which lubricant particles and cerium oxide are added.

  In particular, in an image that requires high transfer efficiency such as a full-color image, the silica has a monodisperse spherical shape having a true specific gravity of 1.3 to 1.9 and a volume average particle size of 80 to 300 nm. Silica is preferred. By controlling the true specific gravity to 1.9 or less, the silica particles can be prevented from falling off from the toner base particles. Further, by controlling the true specific gravity to 1.3 or more, aggregation and dispersion can be suppressed. The true specific gravity of the monodispersed spherical silica is more preferably in the range of 1.4 to 1.8.

If the average particle diameter of the monodispersed spherical silica is less than 80 nm, it may be difficult to reduce the non-electrostatic adhesion between the toner and the image carrier (photoreceptor). In particular, due to stress in the developing device, the monodispersed spherical silica is likely to be embedded in the toner base particles, and the effect of improving developability and transferability may be easily reduced.
On the other hand, when the particle diameter exceeds 300 nm, the silica particles are easily detached from the toner base particles and cannot contribute to the reduction of non-electrostatic adhesion, and at the same time, the detached silica particles are easily transferred to other members, thereby inhibiting charging. In some cases, secondary defects such as image quality defects are likely to occur. The average particle diameter of the monodispersed spherical silica is more preferably 100 to 200 nm.

  The toner used in the present invention can be produced by mixing toner particles and an external additive using a Henschel mixer or a V blender. In addition, when the toner particles are produced by a wet method, external addition can be performed by a wet method.

(Developing apparatus and image forming apparatus)
The developing device of the present invention includes a developer holding body that is provided to face the electrostatic latent image holding body and supplies the developer to the electrostatic latent image holding body, and a developer storage chamber that stores the developer. The developer contains the developer for developing an electrostatic charge image of the present invention as described above, and an electrostatic latent image holding member using a developer held on the developer holding member. The electrostatic latent image is developed thereon to form a toner image.
In addition, the image forming apparatus of the present invention exposes the electrostatic latent image holding member, charging means for charging the electrostatic latent image holding member, and the charged electrostatic latent image holding member, to thereby expose the electrostatic latent image holding member. Using the exposure means for forming an electrostatic latent image on the image carrier and the developer held on the developer carrier, the electrostatic latent image is developed on the electrostatic latent image carrier to form a toner image. Developing means for forming, transfer means for transferring the toner image from the electrostatic latent image holding member to a recording material, and cleaning means for removing residual toner on the surface of the electrostatic latent image holding member after transfer. The developer contains the developer for developing an electrostatic charge image of the present invention described above.
In the process cartridge and the image forming apparatus of the present invention, by using the developer of the present invention, the developer transportability is stabilized over a long period even during long-term use and high-speed operation, and an image in which density unevenness is suppressed can be obtained.

FIG. 1 shows a preferred example of the developing device of the present invention, but the present invention is not limited to this.
The developing device 10 includes a housing 24 including a developer accommodating chamber 18 that accommodates a developer (developer of the present invention) D and a developing roll accommodating chamber 22 that accommodates a developing roll (developer holder) 20. Yes. The housing 24 is formed with an opening that connects the developer storage chamber 18 and the developing roll storage chamber 22, and is stirred by the stirring member 26 from the developer storage chamber 18 to the developing roll storage chamber 22 through the opening. Developer D is supplied.

  Above the developing roll storage chamber 22, an opening portion 16 that exposes a part of the developing roll 20 to the outside is provided, and at this opening portion 16, the developing roll 20 faces the electrostatic latent image holding body 12. . The area where the developing roll 20 and the electrostatic latent image holding body 12 face each other is a developing area, and the developer D is held and conveyed by the developing roll 20 in this developing area. A power source (not shown) for applying a developing bias to the developing roll 20 is connected.

  Further, the developing roll 20 is fixed so as not to rotate, and a magnet roll 28 in which a plurality of magnetic poles 28 </ b> A to 28 </ b> D (four poles in the present embodiment) are alternately arranged, and one direction located around the magnet roll 28. And a non-magnetic cylindrical developing sleeve 30 rotating in the direction B (in FIG. 1).

As the developing sleeve 30, the substrate is used as it is, the substrate surface is subjected to surface treatment such as oxidation, metal plating, polishing or blasting, or the substrate surface is coated with a resin or a charge control agent. Can be suitably used.
The material, shape, structure, etc. of the substrate can be appropriately selected according to the purpose, but the shape is generally cylindrical, and the material is, for example, aluminum, copper, electroless copper, etc. Nickel, electroless nickel, nickel-cadmium diffusion, hard chromium, black chromium, gold, silver, rhodium, platinum, palladium, ruthenium, tin, indium, iron, cadmium and the like. As the oxide film, alumite treatment which is an oxide film of aluminum is most widely used, but oxides such as molybdic acid, iron, copper, etc. may be used.
As the resin layer, phenol resin, epoxy resin, melamine resin, polyurea, polyamide resin, polyimide resin, polyurethane resin, polycarbonate resin, acrylic resin, styrene resin, fluorine resin, silicone resin, or the like can be used. Further, the conductive agent can be dispersed like a resin.

  A layer forming blade (layer regulating member) 32 that contacts the surface of the developing sleeve 30 and forms a thin layer of the developer D on the developing sleeve 30 is attached to the housing 24.

As the layer forming blade (layer regulating member) 32, a plate member such as stainless steel, copper, iron, and resin is used, and a rubber member 32 </ b> A is provided at a portion that contacts the surface of the developing sleeve 30.
As the rubber member 32A, for example, silicone rubber, urethane rubber, butadiene rubber, natural rubber, isoprene rubber, styrene butadiene rubber, butyl rubber, nitrile butadiene rubber, chloroprene rubber, ethylene propylene rubber, epichlorohydrin rubber, or the like is used. Can do.

The behavior of the developer of the present invention during development in the developing device having the above configuration will be described.
The developer is agitated and conveyed by rotation of the agitating member 26 in the developer accommodating chamber 18, and can be supplied from the developer accommodating chamber 18 to the developing roll accommodating chamber 22 through the opening. After the developer adheres to the surface of the developing sleeve 30 by the magnetic force of the magnet roll 28, the layer thickness is regulated by the protruding amount of the layer forming blade (layer regulating member) 32 and the contact pressure, and the developer is triboelectrically charged. The developer that is frictionally charged and conveyed onto the sleeve moves to the electrostatic latent image holding member 12 according to the charge amount and is developed.

  A portion of the developer corresponding to the electrostatic latent image on the developer holding member is consumed, but the other portions are not consumed and are collected inside the developing machine. Part of the unconsumed developer is peeled off by the developer supply member, and the developer on the remaining developer holding member passes through the layer forming blade 32 together with the developer newly supplied by the developer supply member to form a layer again. Is done.

  The developing roll 20 in the present invention has a plurality of grooves extending in the longitudinal direction of the developer holding member as shown in FIG. The width of the plurality of grooves is preferably 2 to 6 times (more preferably 4 to 6 times) the volume average particle diameter of the carrier. In the present invention, the width of the groove refers to the width of the opening of the groove (the length in the direction orthogonal to the longitudinal direction of the developer holding member). If the width of the plurality of grooves is less than twice the volume average particle diameter of the carrier, the effect of improving the transportability may not be sufficient. May be disturbed.

  The shape of each groove (surface shape when cut in a direction orthogonal to the longitudinal direction of the developer holding member) is preferably such that the width of the bottom surface is shorter than the width of the opening, and as shown in FIG. preferable.

  Further, the depth of each groove is preferably 30 μm to 120 μm, and more preferably 50 μm to 120 μm, in order to make the effects of the present invention more remarkable. Furthermore, the number of each groove is preferably 30 to 100, and more preferably 50 to 100.

  It is preferable that the peripheral speed of the developer holder is rotated at 200 mm / sec or more and 600 mm / sec or less. When the peripheral speed of the developer holding member is less than 200 mm / sec, there is a case where the recent increase in speed cannot be achieved or the density is inferior in terms of high density reproducibility. On the other hand, when it exceeds 600 mm / sec, particularly when applied to a small-sized developing machine, trimmer distortion occurs due to insufficient mechanical strength of the developing machine, and density reproducibility is caused by unevenness of the developer on the developer carrier. May be inferior.

  FIG. 2 shows a preferred example of the image forming apparatus of the present invention. The image forming apparatus shown in FIG. 2 exposes the electrostatic latent image holding body 12, charging means 40 appropriately disposed around the electrostatic latent image holding body 12, and the charged electrostatic latent image holding body 12. A latent image forming means (exposure means) 42 for forming an electrostatic latent image on the surface of the electrostatic latent image holding body 12; a developing means 10 for developing the electrostatic latent image with a developer to form a toner image; The image forming apparatus includes a transfer unit 44 that transfers the toner image from the electrostatic latent image holding member 12 to a recording material, a fixing unit 46 that fixes an unfixed transfer image transferred onto the recording material, and a cleaning unit 48. An image forming apparatus.

  In the image forming apparatus shown in FIG. 2, each of these constituent members, that is, an electrostatic latent image holding member (electrophotographic photosensitive member, photosensitive drum) 12, charging means 40, latent image forming means 42, developing means 10, charging The means 40, the transfer means 44, the fixing means 46, the cleaning means 48, and the static elimination means (not shown) are not particularly limited in the present invention, and any conventionally known configuration can be used without any problem. can do. Further, a preferred embodiment of the developing means 10 is the same as the preferred embodiment of the developing device shown in FIG.

Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. In the following description, “part” and “%” mean “part by mass” and “% by mass” unless otherwise specified.
(Preparation of core particles 1 and 2)
Into a Henschel mixer, 350 parts of spherical magnetite particles having an average particle size of 0.5 μm and 150 parts of 0.3 μm spherical magnetite particles were added and stirred sufficiently, and then 5.0 parts of a titanate coupling agent was added. Then, the temperature was raised to about 100 ° C., and mixed and stirred well for 30 minutes to obtain spherical magnetite particles coated with a titanate coupling agent.

  Next, 6.25 parts of phenol, 9.25 parts of 35% formalin, 500 parts of the above-mentioned magnetite particles subjected to lipophilic treatment, 6.25 parts of 25% aqueous ammonia, and 428 parts of water are added to a 1 L four-necked flask. Stir and mix. Next, it was raised to 85 ° C. over 60 minutes with stirring, and reacted at the same temperature for 120 minutes. Then, after cooling to 25 degreeC and adding 500 ml of water, the supernatant liquid was removed and the deposit was washed with water. This was dried at 150 to 180 ° C. under reduced pressure to obtain core particles 1 having a particle size of 35 μm.

  Furthermore, 3.00 parts of melamine, 5.00 parts of 35% formalin, 6.25 parts of 25% aqueous ammonia, and 428 parts of water were added to the core material particles 1 and mixed with stirring. Then, it raised to 90 degreeC in 60 minutes, stirring, and was made to react for 3 hours. Next, this was dried at 150 to 180 ° C. under reduced pressure to obtain core particles having a particle diameter of 35 μm. Then, after cooling to 25 ° C. and adding 500 ml of water, the supernatant is removed, the precipitate is washed with water, air-dried, dried at 150-180 ° C. under reduced pressure, and coated with the first coating layer, Core material particles 2 having a particle size of 35 μm were obtained.

(Preparation of core particles 3 and 4)
In the production of the core material particles 1 and 2, the core particle 3 and the first coating layer are the same as the production of the core material particles 1 and 2 except that the average particle diameter of the spherical magnetite is changed to 0.8 μm. Coated core particles 4 were obtained.

(Preparation of core particles 5 to 8)
MnO: 20 parts and Fe ₂ O ₃ : 80 parts are mixed sufficiently, and these raw material mixtures are mixed and pulverized in a wet ball mill for 10 hours, and then held at 900 ° C. for 1 hour using a rotary kiln to perform preliminary firing. It was. The calcined product thus obtained was pulverized with a wet ball mill for 8 hours to obtain an oxide slurry. To 100 parts of the resulting slurry, 0.3 part of polyvinyl alcohol was added, then granulated and dried with a spray dryer, and then heated in an electric furnace at a temperature of 1250 ° C., oxygen concentration, 0.2% or less. The firing was carried out while maintaining the time. After selecting the magnetic force of the obtained ferrite particles, classification treatment was performed with a sieve having an opening of 20 μm to obtain core material particles 5.

Furthermore, 350 parts of core material particles 5 and 150 parts of 0.3 μm spherical magnetite particle powder were added to a Henschel mixer, and after sufficient stirring, 5.0 parts of a titanate coupling agent was added, and about 100 parts were added. The temperature was raised to 0 ° C. and well mixed and stirred for 30 minutes to obtain ferrite particles coated with a titanate coupling agent.
Next, 3.00 parts of phenol, 5.00 parts of 35% formalin, 6.25 parts of 25% aqueous ammonia, and 428 parts of water were added to a 1 L four-necked flask and mixed with stirring. Then, it raised to 90 degreeC in 60 minutes, stirring, and was made to react for 3 hours.
Next, this was dried at 150 to 180 ° C. under reduced pressure to obtain core material particles 1 having a particle diameter of 35 μm. Then, after cooling to 25 ° C. and adding 500 ml of water, the supernatant is removed, the precipitate is washed with water, air-dried, dried at 150-180 ° C. under reduced pressure, and coated with the first coating layer, Core material particles 6 having a particle size of 35 μm were obtained.

  Core material particles 7 were obtained by the same production method as that for the core material particles 5 except that the firing temperature was changed to 1100 ° C. Further, core material particles 8 which are surface-treated ferrite were obtained by the same production method as the core material particles 6 except that the core material particles 5 were changed to the core material particles 7.

(Production of carrier (1))
[Preparation of coating layer forming raw material solution 1]
The components having the following composition were stirred / dispersed with a stirrer for 60 minutes to prepare a coating forming raw material solution for forming a second coating layer.
Toluene: 65 parts Styrene-methacrylate copolymer (component ratio, 25:75): 11 parts Carbon black (Regal 330; manufactured by Cabot Corporation): 0.3 parts

  12 parts of the coating layer forming raw material solution 1 and 100 parts of the core material particles 2 are put in a vacuum deaeration type mixer, stirred at 90 ° C. for 30 minutes, and further heated to 70 ° C., at 65 kPa for 5 minutes, and 70 kPa. The mixture was stirred for 3 minutes and then further depressurized to deaerate and dry. Furthermore, the carrier (1) was produced by passing through a mesh having an opening of 75 μm. With respect to the obtained carrier (1), the ten-point average roughness Rz of the surface, the standard deviation of the ten-point average roughness Rz, and the average circularity were measured by the methods described above. As a result, the ten-point average roughness Rz of the surface was 2.4, the standard deviation was 0.27, and the average circularity was 0.990.

(Production of carrier (2))
12 parts of the coating layer forming raw material solution 1 and 100 parts of the core material particles 4 are put into a vacuum degassing type feeder and stirred at 90 ° C. for 30 minutes, and then the temperature is raised to 70 ° C. and 65 kPa for 5 minutes. After stirring at 70 kPa for 3 minutes, the pressure was further reduced to deaerate and dry. Furthermore, carrier (2) was produced by passing through a mesh having an opening of 75 μm. Similarly to the carrier (1), the ten-point average roughness Rz, the standard deviation of the ten-point average roughness Rz, and the average circularity were measured by the method described above. As a result, the ten-point average roughness Rz of the surface was 2.4, the standard deviation was 0.25, and the average circularity was 0.992.

(Production of carrier (3))
A carrier (3) was produced by the same production method as the carrier (1) except that the core material particle 2 was changed to the core material particle 3. Similarly to the carrier (1), the ten-point average roughness Rz, the standard deviation of the ten-point average roughness Rz, and the average circularity were measured by the method described above. As a result, a carrier (3) having a 10-point average roughness Rz of 3.0, a standard deviation of 2.10, and a circularity of 0.995 was obtained.

[Preparation of coating layer forming raw material solution 2]
The components having the following composition were stirred / dispersed with a stirrer for 60 minutes to prepare a coating forming raw material solution for forming a second coating layer.
Toluene: 85 parts Styrene-methyl methacrylate copolymer (component ratio, 25: 75: Mw 80000): 15 parts

(Production of carriers (4) to (7))
The carrier (4) is prepared in the same manner as the carrier (1) except that 12 parts of the coating layer forming raw material solution 1 is changed to 10 parts of the coating layer forming raw material solution 2 and the core particle 2 is changed to the core material particle 6. Obtained.
The carrier (5) is prepared in the same manner as the carrier (1) except that 12 parts of the coating layer forming raw material solution 1 is changed to 10 parts of the coating layer forming raw material solution 2 and the core particle 2 is changed to the core material particle 5. Obtained.
The carrier (6) is prepared in the same manner as the carrier (1) except that 12 parts of the coating layer forming raw material solution 1 is changed to 10 parts of the coating layer forming raw material solution 2 and the core particle 2 is changed to the core material particle 8. Obtained.
The carrier (7) is prepared in the same manner as the carrier (1) except that 12 parts of the coating layer forming raw material solution 1 is changed to 10 parts of the coating layer forming raw material solution 2 and the core particle 2 is changed to the core material particle 7. Obtained.
Table 1 shows the surface ten-point average roughness Rz, the standard deviation of the ten-point average roughness, and the average circularity of the obtained carrier.

(Production of Toner (1))
-Preparation of resin fine particle dispersion-
-Styrene: 370 parts-n-butyl acrylate: 30 parts-Acrylic acid: 8 parts-Dodecanethiol: 4 parts-Carbon tetrabromide: 4 parts Emulsion polymer (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) and 10 g of anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in 550 parts of ion-exchanged water. While slowly mixing for 10 minutes, 50 parts of ion-exchanged water in which 4 g of ammonium persulfate was dissolved was added thereto. Subsequently, after the flask was purged with nitrogen, the contents were heated in an oil bath while stirring the flask until the content reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin fine particle dispersion was obtained in which resin particles having an average particle size of 160 nm, a glass transition temperature of Tg of 57 ° C., and a weight average molecular weight Mw of 12,500 were dispersed.

-Preparation of colorant dispersion-
-Magenta pigment (CI Pigment Red 122): 70 parts-Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.): 5 parts-Ion-exchanged water: 240 parts A colorant dispersion in which colorant particles were dispersed was prepared by dissolving and stirring for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA) and then dispersing with an optimizer.

-Preparation of release agent dispersion-
Paraffin wax (HNP0190: Nippon Seiwa Co., Ltd., melting point 85 ° C.): 100 parts
Cationic surfactant (Sanisol B50: manufactured by Kao Corporation): 5 parts Ion exchange water: 240 parts The above ingredients were homogenized in a round stainless steel flask (Ultra Turrax T50: manufactured by IKA) Was then dispersed for 10 minutes using a pressure discharge type homogenizer to prepare a release agent dispersion in which release agent particles having an average particle size of 520 nm were dispersed.

-Preparation of toner-
-Resin fine particle dispersion: 234 parts-Colorant dispersion: 30 parts-Release agent dispersion: 40 parts-Polyaluminum hydroxide (Ahoda Chemical Co., Paho2S): 0.5 parts
・ Ion exchange water: 600 parts
The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then heated to 50 ° C. while stirring the inside of the flask in an oil bath for heating. .

After maintaining at a temperature of 50 ° C. for 30 minutes, the volume average particle size of the aggregated particles produced in the flask was measured and found to be 4.8 μm. Further, the temperature of the heating oil bath was raised and held at 56 ° C. for 1 hour, and then the volume average particle diameter of the aggregated particles was measured and found to be 5.7 μm.
Thereafter, 26 parts of the resin fine particle dispersion was added to the dispersion containing the aggregated particles, and then the temperature of the heating oil bath was maintained at 50 ° C. and held for 30 minutes. Subsequently, 1N sodium hydroxide was added to the dispersion containing the aggregated particles to adjust the pH of the dispersion to 7.0, and then the stainless steel flask was sealed, and stirring was continued using a magnetic seal. Heat to 80 ° C. and hold for 4 hours. After cooling, the toner base particles were filtered off, washed four times with ion exchange water, and then lyophilized to obtain toner particles. The average shape factor of the obtained toner particles was 120.
To 100 parts of the obtained toner particles, 1.0 part of rutile type titanium oxide (average particle diameter 20 nm, n-decyltrimethoxysilane treatment) and silica (silica prepared by vapor phase oxidation method, volume average particle diameter 100 nm, (Silicon oil treatment) Add 1.5 parts and blend for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then remove coarse particles using a sieve with an opening of 45 μm to remove external additives. Added toner (1) was produced.

(Preparation of Toner (2) Toner (2) was obtained in the same manner as in the preparation of toner (1) except that the pH of the dispersion was changed from 7.0 to 6.2. The average shape factor of toner (2) was 112.

(Production of Toner (3))
In the preparation of the toner (1), a toner (3) was obtained in the same manner as in the preparation of the toner (1) except that the pH of the dispersion was changed from 7.0 to 7.5. The average shape factor of toner (3) was 132.

(Production of Toner (4))
A mixture of 100 parts of a styrene-butyl acrylate copolymer (weight average molecular weight Mw = 150,000, copolymerization ratio 80:20), 8 parts of Magenta pigment (CI Pigment Red 122), and 6 parts of carnauba wax. The mixture was kneaded with a fine strainer, pulverized with a jet mill, and then classified with a wind classifier to obtain toner particles. The average shape factor of the toner particles was 145.
To 100 parts of the obtained toner particles, 1.0 part of rutile type titanium oxide (average particle diameter 100 nm, n-decyltrimethoxysilane treatment) and silica (silica prepared by vapor phase oxidation, volume average particle diameter 40 nm, (Silicon oil treatment) Add 1.5 parts and blend for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then remove coarse particles using a sieve with an opening of 45 μm to remove external additives. Added toner (4) was prepared.

(Production of Toner (5))
A mixture of 100 parts of a styrene-butyl acrylate copolymer (weight average molecular weight Mw = 150,000, copolymerization ratio 80:20), 8 parts of Magenta pigment (CI Pigment Red 122), and 6 parts of carnauba wax. The mixture was kneaded with a fine struder, pulverized with a jet mill, spheroidized with warm air, then kryptron (manufactured by Kawasaki Heavy Industries), and classified with an air classifier to obtain toner particles. The average shape factor of the toner particles was 108.
To 100 parts of the obtained toner particles, 1.0 part of rutile type titanium oxide (average particle diameter 20 nm, n-decyltrimethoxysilane treatment) and silica (silica prepared by vapor phase oxidation method, volume average particle diameter 40 nm, (Silicon oil treatment) Add 1.5 parts and blend for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then remove coarse particles using a sieve with an opening of 45 μm to remove external additives. Added toner (5) was produced.

(Production of toners (6) to (9))
In the production of the toner (1), the toners (6), (7) and (7) are produced in the same manner as the production of the toner (1) except that the volume average particle diameter of silica is changed to 80, 190, 45 and 250 nm, respectively. 8) and (9) were obtained, respectively.

<Example 1>
The carrier (1) and the toner (1) are mixed using a V-type blender at a ratio of 90:10 (mass ratio) at 40 rpm for 20 minutes, and a developer (1) that passes through a sieve having an opening of 212 μm. Produced.
Using the developer (1) thus obtained, an image area in a low-temperature and low-humidity (10 ° C., 15% RH) environment using a modified Docu Center Color 400 (Fuji Xerox Co., Ltd.) having the same structure as in FIG. 25,000 sheets were printed at 5%, and then 25,000 sheets were printed at an image area of 10% in an environment of high temperature and high humidity (35 ° C., 60% RH). Thereafter, the following evaluation was performed. The results are shown in Table 1. The modified Docu Center Color 400 has a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit. The developer holder is parallel to the axis and has a groove width (opening) of 180 μm. A groove having a V-shaped groove having 80 grooves and a depth of 80 μm was used. The details are shown in Table 2 (the same applies to the following examples and comparative examples). The evaluation was made on samples after printing 25,000 sheets in a low-temperature and low-humidity environment at a process speed of 250 and 400 mm / sec and after printing 25,000 sheets (50000 sheets in total) at high temperature and high humidity. The following items were implemented. The results are shown in Table 3 (the same applies to the following examples and comparative examples).

(Evaluation of image density)
An image having a 2 cm × 2 cm patch is copied, and five locations in the patch are measured using an image densitometer (X-Rite 404A: manufactured by X-Rite). The case where the difference between the maximum value and the minimum value of the measured value is less than 0.3 is ◎, the case where it is 0.3 or more and less than 0.5 is ○, and the case where it is 0.5 or more and less than 0.8 is × did.

(Evaluation of carrier adhesion)
An image having two 2 cm × 2 cm patches was copied, hard-stopped, and the two development portions on the electrostatic latent image holding member were transferred onto the tape using adhesiveness, and adhered to the tape. Evaluation was made by counting the number of adhered carriers per cm ² . The case where the carrier adhesion was 0 was marked with ◎, the case where it was 1 to 4 was marked with ○, the case where it was 10 to 10 was marked with Δ, and the case where it was 11 or more was marked with ×. The distinction between toner and carrier was determined mainly by the difference in particle size and shape.

(Evaluation of cleaning properties)
The defective cleaning on the photoconductor after printing 25,000 sheets was hard-stopped immediately after the transfer process was completed and visually confirmed. The cleaning failure was evaluated according to the following criteria. No cleaning defect is observed on the surface of the photoconductor, ◯ when one or two traces (streaks) that appear to be defective on the surface of the photoconductor can be observed, and three traces (streaks) that appear to be defective on the surface of the photoconductor. The case where 5 to 5 were produced was indicated by Δ, and the case where 6 or more traces (streaks) that appeared to be poorly cleaned were formed on the surface of the photoreceptor.

<Example 2>
In Example 1, the toner and carrier shown in Table 2 were changed, and the developer holder provided in the modified Docu Center Color 400 used for the evaluation was changed to a developer holder whose surface was blasted. Evaluation was conducted in the same manner as in Example 1.

<Example 3>
In Example 1, the carrier (1) and the toner (1) are changed to the carrier (2) and the toner (3), and the developer holder is parallel to the axis and the groove width (opening) is 80 μm. Evaluation was performed in the same manner as in Example 1 except that a groove having a V-shaped groove having a groove number of 100 and a depth of 80 μm was used.

<Comparative Example 1>
In Example 1, the carrier (1) and the toner (1) are changed to the carrier (3) and the toner (4). The developer holder is parallel to the axis and the groove width (opening) is 80 μm. Evaluation was performed in the same manner as in Example 1 except that a groove having a V-shaped groove having a groove number of 100 and a depth of 80 μm was used.

<Example 4>
In Example 1, the same evaluation as in Example 1 was performed except that the carrier (1) and the toner (1) were changed to the carrier (4) and the toner (5).

<Comparative example 2>
In Example 1, the same evaluation as in Example 1 was performed except that the carrier (1) and the toner (1) were changed to the carrier (5) and the toner (6).

<Example 5>
In Example 1, the carrier (1) and the toner (1) are changed to the carrier (6) and the toner (7), and the developer holder is parallel to the axis and the groove width (opening) is 200 μm. Evaluation was performed in the same manner as in Example 1 except that 50 grooves each having a V-shaped groove having a depth of 80 μm were used.

<Comparative Example 3>
In Example 1, the same evaluation as in Example 1 was performed except that the carrier (1) and the toner (1) were changed to the carrier (7) and the toner (8).

<Example 6>
In Example 1, evaluation was performed in the same manner as in Example 1 except that carrier (1) and toner (1) were changed to carrier (1) and toner (5).

<Comparative Example 4>
In Example 1, the same evaluation as in Example 1 was performed except that the carrier (1) and the toner (1) were changed to the carrier (3) and the toner (5).

<Example 7>
In Example 1, the same evaluation as in Example 1 was performed except that the carrier (1) and the toner (1) were changed to the carrier (2) and the toner (4).

<Comparative Example 5>
In Example 1, the same evaluation as in Example 1 was performed except that the carrier (1) and the toner (1) were changed to the carrier (3) and the toner (4).

<Example 8>
In Example 3, the same evaluation as in Example 3 was performed except that the carrier (2) and the toner (3) were changed to the carrier (1) and the toner (8).

<Comparative Example 6>
In Example 3, the same evaluation as in Example 3 was performed except that the carrier (2) and the toner (3) were changed to the carrier (3) and the toner (8).

<Example 9>
In Example 2, the same evaluation as in Example 2 was performed except that the carrier (1) and the toner (2) were changed to the carrier (1) and the toner (9).

<Comparative Example 7>
In Example 2, the same evaluation as in Example 2 was performed except that the carrier (1) and the toner (2) were changed to the carrier (3) and the toner (9).

From Table 3, since the developer packing on the back of the layer regulating member is reduced, the developer transport amount is stabilized, density unevenness does not occur, and stress in the developing machine can be reduced, so that carrier adhesion is observed. I can't. It can also be seen that the cleaning property can be maintained because the stress on the toner can be reduced.
Further, when there is no V groove on the surface of the developer carrying member, the developer conveying force and the stress are inferior, but the use of the developer of the present invention alleviates the packing state on the back of the layer regulating member. A high-quality image without defects can be obtained.
On the other hand, in the comparative example, because the balance of the ten-point average roughness of the carrier surface, the standard deviation of the ten-point average roughness, and the sphericity is lost, the stress on the developer behind the layer regulating member increases, so the developer loading The frictional force with the body increases. As a result, density shading and carrier adhesion due to conveyance failure are deteriorated. Further, the stress on the toner also increases and the external additive is buried in the toner surface, so that the cleaning property is deteriorated.

  As described above, since the developer of the present invention can relax the packing state behind the layer regulating member, the developer transport amount is stabilized and the stress on the developer can be reduced, so that carrier adhesion and cleaning properties are maintained. it can. Further, by providing the groove of the present invention on the surface of the developer carrying member, high quality image quality can be maintained for a long time even in a high speed machine.

It is a schematic block diagram which shows a suitable example of the image development apparatus of this invention. 1 is a schematic configuration diagram illustrating a preferred example of an image forming apparatus of the present invention.

Explanation of symbols

10 Developing means (developing device)
12 Electrostatic latent image holder 20 Developer roll (developer holder)
26 Stirring member 32 Layer regulating member 40 Charging means 42 Latent image forming means 44 Transfer means 46 Fixing means

Claims (7)

  The ten-point average roughness Rz of the surface is 2 or more and 2.5 or less, the standard deviation of the ten-point average roughness Rz is 0.3 or less, and the average circularity is 0.98 or more. A carrier for developing an electrostatic latent image.   An electrostatic latent image developing developer comprising: a toner and a carrier, wherein the carrier for developing an electrostatic latent image according to claim 1 is used as the carrier.   The electrostatic toner for developing an electrostatic latent image according to claim 2, wherein the toner contains particles having a volume average particle diameter of 50 to 200 nm as an external additive and has a shape factor SF1 of 110 to 140. Developer.   A developer holding body provided opposite to the electrostatic latent image holding body for supplying the developer to the electrostatic latent image holding body; and a developer containing chamber for containing the developer; A developing device comprising the developer for developing an electrostatic image according to claim 2.   The outer peripheral surface of the developer holder has a plurality of grooves extending in the longitudinal direction of the developer holder, and the width of the plurality of grooves is 2 to 6 times the volume average particle diameter of the carrier. The developing device according to claim 4.   An electrostatic latent image holding body, a charging means for charging the electrostatic latent image holding body, and the charged electrostatic latent image holding body are exposed to form an electrostatic latent image on the electrostatic latent image holding body. An exposure means for forming, a developing means for developing the electrostatic latent image on the electrostatic latent image holding body using the developer held on the developer holding body to form a toner image, and the toner image 4. A transfer means for transferring from the electrostatic latent image holding member to a recording material; and a cleaning means for removing residual toner on the surface of the electrostatic latent image holding member after transfer, wherein the developer is claim 2 or 3. An image forming apparatus comprising the developer for developing an electrostatic image described in 1.   The outer peripheral surface of the developer holder has a plurality of grooves extending in the longitudinal direction of the developer holder, and the width of the plurality of grooves is 2 to 6 times the volume average particle diameter of the carrier. The image forming apparatus according to claim 6.

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