JP2013134451A - Development apparatus, magnetic toner used in the development apparatus and development method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a development apparatus having high transfer efficiency and suppressing contamination on a fixation film even after long-term service.SOLUTION: A development apparatus 4 includes a magnetic toner carrier 3 and a regulation member 12. In the magnetic toner carrier 3, a work function value is 4.6-4.9 eV on a surface thereof. In the regulation member 12, a portion making contact with a magnetic toner is made of any of polyphenylene sulfide and polyolefin. The development apparatus employs the magnetic toner including a charge control agent having a center element selected from aluminum, boron, chromium, iron and zinc. If an existing amount of the center element of the charge control agent in the magnetic toner to a binder resin 100 parts by mass is A parts by mass, and an existing amount of the center element of the charge control agent existing on a surface of the magnetic toner to the binder resin 100 parts by mass is B parts by mass, B/A is 0.20-0.60.

Description

  The present invention relates to a developing device and a magnetic toner used in a recording method using electrophotography or the like.

  Since printers and copiers have been used in various ways in recent years, improvements have been made in terms of electrophotographic processes, development, transfer, and fixing. Here, paying attention to the long-term stabilization of the printer, it is important for the stabilization to reduce the load on members and toner in the electrophotographic process.

  Considering the development method, the printer development method includes a two-component development method and a one-component development method. In terms of light load, magnetic one-component development using magnetic toner is most suitable. This is because a member such as a carrier or a toner application roller is not required, and since the toner carrier and the electrostatic latent image carrier are not in contact, the wear of the member and toner can be prevented. Next, paying attention to the transfer, an optimum transfer current value fluctuates when the medium or the environment changes, so that transfer loss is likely to occur.

  In order to solve this problem, there is a method of improving transferability by increasing the transfer current and increasing the electric field from the latent image carrier to the medium. However, when the transfer current is increased, charge leakage to the latent image carrier is induced and there is a risk that the latent image carrier is likely to deteriorate.

  As a technique for suppressing such a risk and improving transferability, improvement of toner transfer efficiency can be considered. Transfer efficiency is the ratio of the amount transferred to the medium (paper, etc.) to the amount of toner on the electrostatic latent image carrier in the transfer step. In general, the transfer efficiency is preferably high in charge amount and sharp in charge distribution with little reverse charge toner and the like. For this reason, there is a need for a developing device / toner having a high toner charge amount and capable of sharply controlling the distribution.

  Further, when the viewpoint is shifted to fixing, the amount of heat supplied to the toner is relatively reduced when fixing on a medium (such as cardboard) that requires a large amount of heat. For this reason, the media is deeply related to the melted state of the toner and greatly affects the fixability. In addition, when the environment changes, for example, when the printer is placed in a low temperature environment, heat is quickly emitted from the fixing member. Therefore, when continuous paper is passed, the time between prints is short, so that the fixing device is not sufficiently heated, and the toner tends to be insufficiently melted. In particular, in a fixing device using a film as a fixing member, such unmelted toner tends to contaminate the fixing film as the fixing member (hereinafter referred to as fixing member contamination). In order to solve this problem, there are methods for increasing the temperature of the fixing device and increasing the amount of the release agent in the toner. However, there is a demerit that increasing the temperature increases the startup time of the printer and increases the power consumption. In addition, when the amount of the release agent contained in the toner is increased, it is generally difficult to control the dispersion of the release agent, so that a difference in chargeability occurs between the toner particles, and the charge distribution becomes broad, resulting in an image. Detrimental effects such as concentration reduction and fog deterioration occur. For this reason, there is a demand for a toner with good fouling of the fixing member without image defects.

  In order to deal with such problems, a technique is disclosed in which a metal complex salt compound is externally added to firmly adhere to toner particles, fog is reduced, and image density stability is improved (see Patent Document 1).

  In addition, a technique for improving the charging stability by controlling the ratio of the amount of charge control agent present in the toner particle inner surface layer to the total amount of charge control agent is disclosed (see Patent Document 2).

  Furthermore, a technique is disclosed in which toner particles are coated with a low-crystalline or non-crystalline metal complex compound or metal salt to improve toner chargeability and improve transferability (see Patent Document 3).

  However, the above-described techniques have not yet solved the problems such as transferability after long-term use and fouling of the fixing member, and leave room for improvement.

JP-A-9-190006 Japanese Patent No. 3486471 Japanese Patent No. 4154078

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device and a magnetic toner that have high transfer efficiency even after long-term use and that suppress fouling of a fixing member.

The present invention relates to an electrostatic latent image carrier on which an electrostatic latent image is formed, a magnetic toner that develops the electrostatic latent image, a magnetic toner carrier that carries and carries the magnetic toner, and the magnetic toner carrier In a developing device provided with a regulating member that abuts against the magnetic toner and regulates the magnetic toner,
The magnetic toner carrier has a surface work function value of 4.6 eV or more and 4.9 eV or less,
In the regulating member, the part in contact with the magnetic toner is either polyphenylene sulfide or polyolefin,
The magnetic toner is
i) magnetic toner particles containing a binder resin, magnetic powder, and a charge control agent, and inorganic fine powder,
ii) is negatively charged,
iii) The average circularity is 0.965 or less,
The charge control agent is a compound having, as a central element, an element selected from the group consisting of aluminum, boron, chromium, iron, and zinc, and 1.50 parts by mass or more with respect to 100 parts by mass of the binder resin. 0 parts by mass or less,
When the abundance of the central element of the charge control agent contained in the magnetic toner is A and the abundance of the central element of the charge control agent present on the magnetic toner surface is B, B / A is expressed by the following formula ( The present invention relates to a developing device satisfying 1).

  By using the developing device of the present invention, the transfer efficiency is high and the fixing film can be satisfactorily suppressed.

FIG. 4 is a schematic diagram illustrating a state in which toner existing in the vicinity of the surface of a toner carrier is conveyed. 1 is a schematic cross-sectional view illustrating an example of an image forming apparatus that can be used in the present invention. FIG. 4 is a schematic cross-sectional view illustrating an example of a method for fixing a toner regulating member to a developing container. The graph which shows the amount of the charge control agent extracted with respect to the shaking time. The graph which shows the elution amount with respect to the surface charge control agent amount. Work function measurement curve.

  As a result of diligent investigations by the present inventors, in order to improve the transfer efficiency, the present inventors have diligently studied, and in order to improve the transfer efficiency, the toner surface shape has appropriate irregularities, It was very important to increase the charge amount of the toner on the toner carrier and to make the charge amount uniform. Furthermore, by using a specific charge control agent, high transfer efficiency and fixing member contamination can be improved, leading to the present invention.

  First, considering the behavior of the toner in the transfer process, the transfer is performed by transferring the toner on the electrostatic latent image carrier to a medium (paper, OHP sheet, etc.) on a transfer member such as a transfer roller. The driving force at which the toner moves from the electrostatic latent image carrier to the medium side is a transfer bias applied to the transfer member, and the response to the bias is the main factor that determines the transfer performance. That is, transferability can be improved by increasing the bias response of the toner image formed on the electrostatic latent image carrier.

  The bias responsiveness is correlated with the charge amount of the toner. When the charge amount of the toner is high, the bias responsiveness is high. However, in general, there is a distribution in the charge amount of the toner on the toner carrier, and even if the charge amount of the toner as a whole is high, it includes toner with a low charge amount. The toner also has a charge distribution. Further, when the charge amount of the toner is high, the charge amount distribution tends to widen. This is a remarkable tendency particularly in magnetic one-component development, and it is difficult to achieve both a high charge amount and a sharp charge amount distribution, and it is difficult to improve transferability from the viewpoint of bias response.

  The inventors consider this cause as follows. In magnetic one-component development, toner is conveyed by a toner carrier, and the toner conveyance amount is regulated by a toner regulating member. At this time, the toner behaves as follows at a portion where the toner carrier and the toner regulating member abut (hereinafter referred to as a regulating portion).

  In the restricting portion, the rotation force of the toner carrying member and the pressure from the restricting member are applied, and further, the toner existing in the vicinity of the surface of the toner carrying member is conveyed while being exchanged so as to be mixed due to the unevenness of the toner carrying member ( (See FIG. 1). For this reason, the toner present in the vicinity of the surface of the toner carrying member becomes negatively charged by contact with the toner carrying member. On the other hand, the toner in the vicinity of the toner regulating member is present at a position relatively far from the irregularities on the surface of the toner carrying member, so that the toner is hardly mixed. In general, since the toner regulating member has a polarity opposite to the charging polarity of the toner, an electrostatic force acts between the toner regulating member and the toner, and the toner becomes more difficult to move near the toner regulating member. It is difficult to replace toner near the regulating member. For this reason, with respect to the toner in the vicinity of the toner regulating member, only the toner in contact with the surface of the toner regulating member is charged, and the toner that exists inside and does not replace cannot be sufficiently charged.

  In order to increase the charge amount of the toner, there are generally means for increasing the contact pressure of the toner regulating member or making the material of the toner regulating member more highly chargeable. However, with these means, the movement of the toner is more restricted, and it becomes difficult for the toner to be mixed in the restriction part, and only the charge amount of the toner in contact with the surface of the toner restriction member is increased, resulting in a distribution of the charge amount of the toner. Become broad.

In contrast, the inventors have
i) Toner replacement is good in the regulation section.
ii) the toner is charged quickly;
If these two conditions are satisfied, the charging of the magnetic toner used for development on the magnetic toner carrier becomes high and sharp, and as a result, the bias response of the toner image formed on the electrostatic latent image carrier It was thought that the property would increase, and the present invention was reached.

  In order to achieve the above two conditions, i) polyphenylene sulfide (hereinafter referred to as “PPS”) or polyolefin is used as a toner regulating member, and ii) the work function value on the surface of the toner carrier is 4.6 eV or more. It was important that the surface shape and composition of the toner be controlled.

  The replacement of the toner in the vicinity of the toner regulating member is greatly improved by using a toner regulating member in which the portion in contact with the toner is made of PPS or polyolefin. PPS and polyolefin are almost the same potential or weakly negative as compared with a general negatively chargeable toner, and the toner in the vicinity of the toner regulating member is hardly charged due to sliding / friction with the toner regulating member. For this reason, it is considered that the electrostatic force on the toner regulating member becomes extremely small, and the adhesion force of the toner to the toner regulating member is reduced. For this reason, the toner in the vicinity of the toner regulating member can be replaced well, and the charge amount distribution is considered to be sharp.

However, when the contact portion of the toner regulating member with the toner is formed of PPS or polyolefin, since the ability to charge the toner is very low, the charge amount of the toner is reduced. Therefore, toner charging is dependent on contact and rubbing with the toner carrier.
It is necessary to improve the chargeability of the magnetic toner carrier and the chargeability of the toner.
In the present invention, it is important that the work function value on the surface of the magnetic toner carrier is 4.6 eV or more and 4.9 eV or less.

  The work function is generally an index of the ease with which free electrons are emitted, and the lower the value, the easier it is to release free electrons. Here, considering the charging of the magnetic toner carrier surface and the magnetic toner, if the work function value of the magnetic toner carrier surface is small, free electrons are easily exchanged when the toner contacts and rubs. Easily charged. For this reason, it is important that the work function value of the surface of the magnetic toner carrier is 4.9 eV or less.

  Further, when the work function value on the surface of the magnetic toner carrying member is 4.6 eV or more, it is possible to suppress the charge amount of the magnetic toner from being excessive, and it is possible to suppress an increase in mirror power. As a result, the toner on the magnetic toner carrier can move easily, and the charge amount distribution can be sharpened.

Next, the magnetic toner of the present invention contains a charge control agent that is a compound having an element selected from the group consisting of aluminum, boron, chromium, iron, and zinc as a central element. A charge control agent composed of a compound in which these central elements are divalent or trivalent has high electron accepting properties and exhibits good triboelectric charging properties. Further, the amount of the charge control agent contained in the magnetic toner is 1.50 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the binder resin. It is important that B / A satisfies the following expression (1), where A is the mass of the element and B is the mass of the central element of the charge control agent present on the toner surface.
0.20 ≦ B / A ≦ 0.60 Formula (1)

  The total amount of the charge control agent is 1.50 parts by mass or more with respect to 100 parts by mass of the binder resin, and that B / A satisfies the above range, the charge control agent is sufficiently present on the surface of the magnetic toner. Means that. The upper limit is a general value, and it is considered that even if the content exceeds 10.0 parts by mass, it does not contribute to the improvement of the charging property of the magnetic toner.

  A sufficient amount of charge control agent is present on the surface of the magnetic toner, and the magnetic toner carrier has a specific work function, so that the magnetic toner is quickly charged and has a sufficient charge amount. It becomes like this.

  When B / A is larger than 0.60, the transferability also deteriorates. This is because the magnetic toner surface is unevenly distributed in excess of 60% of the total charge control agent amount, so that the hygroscopicity of the magnetic toner surface is significantly higher than that inside. For this reason, it is considered that the transfer current leaks due to the lower resistance near the surface, and the transferability is lowered.

As described above, the toner restricting member is made of PPS or polyolefin to prevent the toner from sticking to the toner restricting member, so that the toner can be satisfactorily replaced in the restricting portion, and the work function of the toner carrier is specified. The charging speed of the toner is increased by setting the value and appropriately controlling the amount of the charge control agent on the toner surface. Due to these synergistic effects, the charge amount of the toner is high, and the charge amount distribution becomes very sharp. This makes it possible to obtain a high-quality image with high responsiveness to the transfer bias, improved transferability, and suppressed transfer omission.
Further, in the developing device of the present invention, fouling of the fixing member can be improved.

  Considering the fixing process, the medium on which the toner is placed passes through the fixing nip through the transfer process, and is heated and pressed by the fixing member, whereby the toner is melted and fixed on the medium.

  Here, if the adhesion force between the toner and the medium (mainly paper) is low during heating and pressurization at the fixing nip, the toner is applied to a member on the pressure side of the fixing member (in the case of a configuration using a fixing film). Will contaminate the member.

  In order to increase the adhesion of the toner to the paper, it is important that (1) the toner is sufficiently melted and (2) it is difficult to peel off the paper.

  In order to sufficiently melt the toner (1), there are a method of widening the fixing nip and a method of raising the fixing temperature as described above. However, when the fixing nip is widened, the toner is sufficiently melted, while the contact time with the fixing member is increased, so that the fixing member contamination tends to become more prominent. Also, raising the fixing temperature is not preferable because the startup time becomes longer.

  As a technique for melting the toner while suppressing these adverse effects, it is possible to make the applied toner amount uniform in the image. At the time of fixing, heat is applied to a portion far from the paper (hereinafter referred to as the upper layer), heat is sequentially conducted to the portion close to the paper (hereinafter referred to as the lower layer), and is fixed to the paper by melting. For this reason, when the amount of applied toner is non-uniform, the lower layer tends to be insufficiently melted at a portion where the toner overlap is large and the applied amount is large. If toner that is not sufficiently melted is present in the lower layer, the toner tends to be peeled off from the lower layer, and the toner adheres to the fixing member, resulting in contamination of the fixing member.

  Therefore, it is important to uniformly put the toner on the paper for improving the fouling of the fixing member, and it is important to control the toner behavior in both the development process and the transfer process.

  First, considering the development process, the toner is charged on the toner carrier, and the electric field generated by the potential difference between the electrostatic latent image formed on the electrostatic latent image carrier and the bias applied on the toner carrier. Development is performed by flying with the power of.

  At this time, when the toner before flying is aggregated on the toner carrier, the toner flies to the electrostatic latent image carrier while maintaining the aggregation, and reaches the paper while being aggregated through the transfer process. For this reason, it is possible to suppress the aggregation on the paper by suppressing the aggregation of the toner on the toner carrier. Factors that cause aggregation include physical aggregation, liquid crosslinking, magnetic aggregation, and electrostatic aggregation. However, according to the study by the present inventors, the magnetic and electrostatic aggregation force is strong, and electrostatic aggregation is particularly dominant. It was the target.

  Considering electrostatic aggregation, a portion having a difference in charge amount on the toner surface is relatively positive and negative, so that electrostatic attraction occurs due to electrostatic attraction. Therefore, it is important to make the charge amount on the toner surface uniform.

  As described above, in the present invention, the toner on the toner carrier has a sharp charge amount distribution. For this reason, the electrostatic cohesion force is extremely small, and the electrostatic aggregation on the toner carrier can be suppressed, so that the aggregation can be reduced in any process on the toner carrier, the electrostatic latent image carrier and the paper.

  The second point to increase the adhesion of toner to paper is to make it difficult to separate from the paper. To that end, it is important to give the toner appropriate irregularities and to increase the charge amount. Met.

  Specifically, the average circularity of the toner is 0.965 or less with respect to the unevenness. If the toner surface has irregularities, the toner in the lower layer is applied to the fiber of the paper when it is transferred, so that it cannot be easily removed from the paper. The average circularity of the toner is preferably 0.900 or more from the viewpoint of fluidity. More preferably, it is 0.930 or more.

  As described above, the toner on the toner carrier has a high charge amount, a sharp charge amount distribution, and a toner shape having irregularities, so that transferability is high and fouling of the fixing member is suppressed. It became possible.

  In the present invention, in order to adjust the resistance value of the resin layer on the surface of the toner carrying member, the following conductive particles can be contained in the resin layer. Fine powder of metal (aluminum, copper, nickel, silver, etc.), particles of conductive metal oxide (antimony oxide, indium oxide, tin oxide, titanium oxide, zinc oxide, molybdenum oxide, potassium titanate, etc.), crystalline graphite , Various carbon fibers, conductive carbon black.

  In the present invention, it is possible to adjust the work function value of the surface layer of the toner carrying member by appropriately selecting the type of the conductive particles and appropriately adjusting the amount of addition.

  For example, the work function value can be lowered by adding many conductive particles having a low work function value such as metal powder such as aluminum, copper, silver, nickel, and graphite. Further, it is possible to increase the work function value by a method such as adding oxidized carbon black or reducing the amount of conductive particles added.

  As a specific oxidation treatment method for carbon black, known methods can be applied, and examples thereof include a surface oxidation treatment method using ozone and the like, an oxidation treatment method using potassium permanganate, and the like. By oxidizing the surface of carbon black by such a method, surface functional groups such as carboxyl groups and sulfonic acid groups are imparted to the surface of carbon black, and the work function is increased by the action of the surface functional groups.

  Further, the abundance A of the central element of the charge control agent contained in the toner can be controlled by the addition amount of the charge control agent and the amount of the central element contained in the charge control agent. Further, since B / A is an index representing the degree of exposure of the charge control agent to the toner surface, it can also be controlled by a toner manufacturing method or the like. Specific examples of the manufacturing method include a method of externally adding a charge control agent. As a wet method, for example, when the toner is produced in an aqueous medium, the charge control agent is hydrophilic to the polymerizable monomer, and thus can be localized on the toner surface. However, since this method often increases the circularity, it is necessary to pay attention to the surface shape.

  In the present invention, the surface roughness (RaS) of the toner carrier is 0.60 μm or more and 1.50 μm or less, and the surface roughness (RaB) of the portion of the toner regulating member that contacts the magnetic toner and the surface of the toner carrier. The ratio of roughness (RaS) (RaS / RaB) is preferably 1.0 or more and 3.0 or less. More preferably, RaS is 0.80 to 1.3 μm, and RaS / RaB is 1.5 to 2.5.

  As described above, in the present invention, it is very important to satisfactorily replace the toner in the restricting portion. This driving force is unevenness on the surface of the toner carrier, but the toner in the vicinity of the toner regulating member present at a position relatively far from the toner carrier is not easily affected. Therefore, by providing the toner regulating member surface with irregularities, the replacement of the toner becomes good.

  In order to bring the surface roughness (RaS) of the toner carrier in the present invention into the above range, for example, the polishing state of the surface layer of the toner carrier is changed, or spherical carbon particles, carbon fine particles, graphite, resin fine particles, etc. are added. This is possible. Examples of the method for adjusting the surface roughness (RaB) of the toner regulating member include a method of taper polishing the surface of the toner regulating member.

The toner of the present invention, measurement magnetic field 795.8 kA / saturation magnetization σs at m is 35Am ² / kg or more, 45Am ² / kg or less, preferably the residual magnetization σr is less than 3.0Am ² / kg.

  As described above, it is important to suppress agglomeration in the development and transfer processes with respect to fixing film contamination. Although magnetic aggregation is a major factor that promotes aggregation, generally, simply lowering the magnetic force weakens the magnetic binding force with the toner carrier and makes it impossible to control the behavior of the toner during development. Therefore, good image formation is possible.

  The toner of the present invention preferably has a weight average particle diameter (D4) of 3.0 μm or more and 12.0 μm or less, and more preferably 4.0 μm or more and 10.0 μm or less. If the particle diameter of the toner is within the above range, good fluidity can be obtained and development can be performed faithfully to the latent image. For this reason, a good image excellent in dot reproducibility can be obtained.

  The glass transition temperature (Tg) of the toner is preferably 40.0 ° C. or higher and 70.0 ° C. or lower. A glass transition temperature of 40.0 ° C. or higher and 70.0 ° C. or lower is preferable because storage stability and durability can be improved while maintaining good fixability.

  The charge control agent contained in the toner has aluminum, boron, chromium, iron or zinc as a central element. Examples of the charge control agent that can be used include compounds in which an aromatic carboxylic acid such as salicylic acid, alkylsalicylic acid, dialkylsalicylic acid, naphthoic acid, dicarboxylic acid, and dibenzylic acid is coordinated to a metal, and azo compounds. In addition, a boron compound and calixarene coordinated with the central element can be used. Among these, when the azo compound having the central element is present on the toner surface, it is preferable because the chargeability is easily uniformed. It is more preferable that the central metal is chrome because the charge becomes high.

  Examples of the binder resin used in the toner of the present invention include styrene such as polystyrene and polyvinyltoluene, and homopolymers thereof and styrene-propylene copolymers, styrene-vinyltoluene copolymers, and styrene-vinylnaphthalene copolymers. Polymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene -Methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl Ether copolymer, styrene Styrene copolymers such as vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, polymethyl methacrylate, poly Butyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, and the like can be used, and these can be used alone or in combination.

  The toner may contain a release agent as necessary to improve the fixing property. A known release agent can be used as the release agent. Specifically, paraffin wax, microcrystalline wax, petroleum wax such as petrolatum and derivatives thereof, montan wax and derivatives thereof, hydrocarbon wax and derivatives thereof by Fischer-Tropsch method, polyolefin wax and derivatives thereof typified by polyethylene, Natural waxes such as carnauba wax and candelilla wax and their derivatives, ester waxes and the like. Here, the derivatives include oxides, block copolymers with vinyl monomers, and graft modified products. As the ester wax, monofunctional ester wax, bifunctional ester wax, and other polyfunctional ester waxes such as tetrafunctional and hexafunctional can be used.

  The release agent preferably has an endothermic peak top temperature of 50 ° C. or more and 90 ° C. or less in differential scanning calorimetry. When the endothermic peak top temperature is within the above range, the toner is easily plasticized at the time of fixing, and the fixing property is improved. Moreover, even when left in a high-temperature and high-humidity environment, wax bleeding and the like are unlikely to occur.

  When using a mold release agent, it is preferable to use 2 parts by mass or more and 30 parts by mass or less of the mold release agent with respect to 100 parts by mass of the binder resin. Within the above range, the fixability is improved and the storage stability of the toner tends to be good, which is preferable.

  The toner of the present invention contains a magnetic substance, and the addition amount is preferably 20 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the binder resin. When the addition amount of the magnetic material is 20 parts by mass or more and 150 parts by mass or less, the coloring power is good, the fog is small, and good fixability can be obtained.

  Note that the content of the magnetic substance in the toner can be measured using a thermal analyzer, TGA7, manufactured by PerkinElmer. In the measurement method, the toner is heated from normal temperature to 900 ° C. at a temperature rising rate of 25 ° C./min in a nitrogen atmosphere, and the weight loss from 100 ° C. to 750 ° C. is defined as the binder resin amount, and the remaining mass is approximated. The amount of magnetic material.

Magnetic material, it is preferable that a BET specific surface area is less than 2.0 m ² / g or more 20.0 m ² / g by a nitrogen adsorption method, not more than 3.0 m ² / g or more 10.0 m ² / g More preferred.

  The shape of the magnetic material includes a polyhedron, octahedron, hexahedron, sphere, needle shape, flake shape, etc., but a polyhedron, octahedron, hexahedron, sphere and the like having a small anisotropy can reduce image density. It is preferable in terms of enhancement.

  The magnetic material can be manufactured, for example, by the following method. Specifically, an aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide equivalent to or equivalent to the iron component to the ferrous salt aqueous solution. Air was blown in while maintaining the pH of the prepared aqueous solution at 7.0 or higher, and ferrous hydroxide was oxidized while heating the aqueous solution to 70 ° C. or higher, and seed crystals serving as the core of the magnetic iron oxide particles were formed. First generate.

  Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. The pH of the liquid is maintained at 5.0 or higher and 10.0 or lower, and the reaction of ferrous hydroxide proceeds while blowing air, and magnetic iron oxide particles are grown with the seed crystal as a core. At this time, it is possible to control the shape and magnetic properties of the magnetic iron oxide by selecting an arbitrary pH, reaction temperature, and stirring conditions. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably not less than 5.0. Magnetic iron oxide particles can be obtained by filtering, washing and drying the thus obtained magnetic iron oxide particles by a conventional method.

In addition, you may process a magnetic body surface and may provide a silica layer on a magnetic body surface by adjustment in a manufacturing process.
The toner according to the present invention can be produced by any known method. When manufacturing by a pulverization method, first, using a mixer such as a Henschel mixer, a ball mill or the like, thoroughly mix components necessary for the toner, such as a binder resin, a magnetic material, and a release agent, and other additives. . Thereafter, the toner material is dispersed or dissolved by using a heat kneader such as a heating roll, a kneader, or an extruder to disperse or dissolve the toner material, and after cooling and solidification, pulverization, and surface treatment as necessary to obtain toner particles. be able to. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.

  It is preferable that an inorganic fine powder is externally added to the toner, and the inorganic fine powder preferably has a primary particle number average particle diameter (D1) of 4 nm or more and 80 nm or less, more preferably 6 nm or more and 40 nm or less. It is.

  When the number average particle diameter (D1) of the primary particles of the inorganic fine powder is 4 nm or more and 80 nm or less, the fluidity of the toner is excellent, and more uniform chargeability can be obtained. In the present invention, the number average particle diameter (D1) of the primary particles of the inorganic fine powder is measured using a photograph of the toner magnified by a scanning electron microscope.

  As the inorganic fine powder, silica, titanium oxide, alumina or the like can be used. As the fine silica powder, for example, both a so-called dry method produced by vapor phase oxidation of silicon halide or dry silica called fumed silica, and so-called wet silica produced from water glass or the like can be used. is there.

  The addition amount of the inorganic fine powder is preferably 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the toner particles. The addition amount of the inorganic fine powder is preferably in the above range since the toner can be given good fluidity and the fixing property is not hindered. The content of the inorganic fine powder can be quantified using a calibration curve prepared from a standard sample using fluorescent X-ray analysis.

  Next, an example of an image forming apparatus to which the developing device according to the present invention is applied will be specifically described with reference to FIG. In FIG. 2, reference numeral 1 denotes an electrostatic latent image carrier (hereinafter also referred to as a photoconductor), which includes a charging roller 2, a developing device 4 having a toner carrier 3, a transfer roller 5, a cleaner container 6, and a cleaning blade. 7, a fixing device 8, a pickup roller 9, and the like are provided. The electrostatic latent image carrier 1 is charged by a charging roller 2. Then, exposure is performed by irradiating the electrostatic latent image carrier 1 with laser light by the laser generator 11, and an electrostatic latent image corresponding to a target image is formed. The electrostatic latent image on the electrostatic latent image carrier 1 is developed with the one-component magnetic toner by the developing device 4 to form a toner image. The toner image is transferred onto the transfer material by the transfer roller 5 in contact with the electrostatic latent image carrier via the transfer material. The transfer material on which the toner image is placed is conveyed to the fixing device 8 and fixed on the transfer material. Further, the toner partially left on the electrostatic latent image carrier is scraped off by the cleaning blade 7 and stored in the cleaner container 6.

  In the charging process, a contact portion is formed between the electrostatic latent image carrier and the charging roller, and a predetermined charging bias is applied to the charging roller to charge the surface of the electrostatic latent image carrier to a predetermined polarity and potential. A contact charging device can be used. Further, by performing contact charging in this way, stable and uniform charging can be performed, and further, there is an effect that generation of ozone is reduced.

  However, in general, when a fixed type charging member is used, it is difficult to maintain uniform contact between the charging member and the rotating image carrier, and uneven charging tends to occur. For this reason, it is more preferable to use a charging member (charging roller) that rotates in the same direction as the image carrier in order to maintain uniform contact with the image carrier and perform uniform charging.

  As a preferable process condition when the charging roller is used, the contact pressure of the roller is 4.9 to 490.0 N / m (5.0 to 500.0 g / cm), and the DC voltage or the AC voltage is applied to the DC voltage. Superposed ones are used. When the AC voltage is superimposed, it is preferable that the AC voltage is 0.5 to 5.0 kVpp, the AC frequency is 50 Hz to 5 kHz, and the absolute value of the DC voltage is 200 to 1500 V. The polarity of the voltage depends on the developing device used.

  As a waveform of the AC voltage used in the charging process, a sine wave, a rectangular wave, a triangular wave, or the like can be used as appropriate.

  The material of the charging roller is not limited to the elastic foam, but as the material of the elastic body, ethylene-propylene-diene polyethylene (EPDM), urethane, butadiene acrylonitrile rubber (NBR), silicone rubber, isoprene rubber, etc. In order to adjust the resistance, a rubber material in which a conductive material such as carbon black or a metal oxide is dispersed, or a foamed material of these materials can be used. It is also possible to adjust the resistance using an ion conductive material without dispersing the conductive particles or in combination with the conductive particles.

  Moreover, aluminum, SUS, etc. are mentioned as a metal core used for a roller member. The roller member is disposed in pressure contact with the electrostatic latent image carrier with a predetermined pressing force to form a charging contact portion that is a contact portion between the roller member and the electrostatic latent image carrier.

Next, the contact transfer process will be specifically described.
The contact transfer process is a process in which the electrostatic latent image carrier is electrostatically transferred to the recording medium while contacting the transfer member through the recording medium. It is preferably 9.9 N / m (3.0 g / cm) or more, more preferably 19.6 N / m (20.0 g / cm) or more. If the linear pressure as the contact pressure is less than 2.9 N / m (3.0 g / cm), the recording medium is likely to be transported and transfer defects are likely to occur.

  Further, the effect of the present invention becomes more remarkable in a developing device having a small-diameter electrostatic latent image carrier having a diameter of 50 mm or less. That is, in the case of an electrostatic latent image carrier having a small diameter, since the curvature in the transfer region is large, good transfer tends to be difficult, but good transfer is possible with the configuration of the present invention. For the same reason, the effect becomes more remarkable in the case of a developing device having a belt-like electrostatic latent image carrier having a radius of curvature of 25 mm or less at the transfer portion.

  In the developing device of the present invention, in order to obtain high image quality without fogging, the layer thickness is thinner on the magnetic toner carrier than the closest distance (between SD) of the magnetic toner carrier and the electrostatic latent image carrier. It is preferable to apply a magnetic toner and develop an electrostatic latent image using the magnetic toner in a development process. In general, a magnetic cut or a regulating blade is known as a regulating member that regulates the magnetic toner on the magnetic toner carrier. In the present invention, it is preferable to use a regulating blade. In the regulating blade, it is easy to use polyphenylene sulfide or polyolefin as the material of the portion that contacts the magnetic toner as described above.

  In the present invention, the regulating member can be a polyphenylene sulfide or a polyolefin molded into a sheet shape as it is, but a member obtained by bonding or coating these resins on a metal substrate (metal elastic body) is also suitable. Can be used.

  Polypropylene and polyethylene can be used as the polyolefin, and specifically, Novatec PP FW4BT (Nippon Polypro) and Thermolan 3855 (Mitsubishi Chemical) can be suitably used. As polyphenylene sulfide, Torelina (Toray Industries, Inc.) can be used suitably. In particular, it is preferable to use a toner regulating member by laminating a polyolefin film (polypropylene film, polyethylene film, etc.) or a polyphenylene sulfide film on a metal elastic body.

  In addition, polyphenylene sulfide and polyolefin may contain other resins and additives in order to adjust chargeability and the like as long as the ratio is 20% by mass or less.

  In the present invention, the regulating member can be a polyphenylene sulfide or polyolefin molded into a sheet shape as it is, but a material obtained by bonding these resins on a metal elastic body or a coated material can also be suitably used. .

  The contact pressure between the regulating member and the toner carrier is preferably 4.9 to 118.0 N / m (5 to 120 g / cm) as the linear pressure in the toner carrier bus direction.

  The toner carrier used in the present invention is preferably a conductive cylinder (developing roller) formed of a metal or alloy such as aluminum or stainless steel. A conductive cylinder may be formed of a resin composition having sufficient mechanical strength and conductivity, or a conductive rubber roller may be used.

  The toner carrier preferably has a fixed magnet having multiple poles inside, and preferably has 3 to 10 magnetic poles.

  In the present invention, in the developing step, an alternating electric field is applied as a developing bias to a toner carrier provided opposite to the electrostatic latent image carrier, and an electrostatic latent image on the electrostatic latent image carrier is formed. Preferably, the toner image is transferred to form a toner image, and the applied developing bias may be a voltage obtained by superimposing an alternating electric field on a DC voltage.

  As the waveform of the alternating electric field, a sine wave, a rectangular wave, a triangular wave, or the like can be used as appropriate. Further, it may be a pulse wave formed by periodically turning on / off a DC power source. As described above, a bias whose voltage value periodically changes can be used as the waveform of the alternating electric field.

Next, a method for measuring each physical property will be described.
(1) Average particle size and particle size distribution of toner The weight average particle size (D4) of the toner is a precision particle size distribution measuring device “Coulter Counter Multisizer 3” (registered trademark) equipped with an aperture tube of 100 μm by a pore electric resistance method. 20,000 effective measurement channels using the Beckman Coulter Multisizer 3 Version 3.51 (Beckman Coulter, Inc.) and attached dedicated software “Beckman Coulter Multisizer 3 Version 3.51” for measurement condition setting and measurement data analysis Measurement was performed with 5,000 channels, and the measurement data was analyzed and calculated.

  As the electrolytic aqueous solution used for the measurement, special grade sodium chloride is dissolved in ion-exchanged water so as to have a concentration of about 1% by mass, for example, “ISOTON II” (manufactured by Beckman Coulter, Inc.) can be used.

Prior to measurement and analysis, the dedicated software was set as follows.
In the “Standard Measurement Method (SOM) Change Screen” of the dedicated software, set the total count in the control mode to 50000 particles, set the number of measurements once, and set the Kd value to “standard particles 10.0 μm” (Beckman Coulter, Inc.) Set the value obtained using The threshold and noise level are automatically set by pressing the threshold / noise level measurement button. Also, the current is set to 1600 μA, the gain is set to 2, the electrolyte is set to ISOTON II, and the aperture tube flash after measurement is checked.

  In the “pulse to particle size conversion setting screen” of the dedicated software, the bin interval is set to logarithmic particle size, the particle size bin is set to 256 particle size bin, and the particle size range is set to 2 μm to 60 μm.

The specific measurement method is as follows.
1-1) About 200 ml of the electrolytic solution is placed in a glass 250 ml round bottom beaker exclusively for Multisizer 3, set on a sample stand, and the stirrer rod is stirred counterclockwise at 24 rpm. Then, dirt and bubbles in the aperture tube are removed by the “aperture flush” function of the analysis software.

  1-2) About 30 ml of the electrolytic aqueous solution is put in a glass 100 ml flat bottom beaker, and “Contaminone N” (nonionic surfactant, anionic surfactant, organic builder pH 7 precision is used as a dispersant therein. About 0.3 ml of a dilute solution obtained by diluting a 10% by weight aqueous solution of a neutral detergent for measuring device washing (manufactured by Wako Pure Chemical Industries, Ltd.) 3 times by weight with ion exchange water is added.

  1-3) Two oscillators with an oscillation frequency of 50 kHz are incorporated in a state where the phase is shifted by 180 degrees, and placed in a water tank of an ultrasonic disperser “Ultrasonic Dissipation System Tetora 150” (manufactured by Nikka Ki Bios) with an electrical output of 120 W. A predetermined amount of ion-exchanged water is put, and about 2 ml of the above-mentioned Contaminone N is added to this water tank.

  1-4) The beaker of 1-2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. And the height position of a beaker is adjusted so that the resonance state of the liquid level of the electrolyte solution in a beaker may become the maximum.

  1-5) In a state where the electrolytic aqueous solution in the beaker of 1-4) is irradiated with ultrasonic waves, about 10 mg of toner is added to the electrolytic aqueous solution little by little and dispersed. Then, the ultrasonic dispersion process is continued for another 60 seconds. In the ultrasonic dispersion, the temperature of the water tank is appropriately adjusted so as to be 10 ° C. or higher and 40 ° C. or lower.

  1-6) Into the round bottom beaker of (1) installed in a sample stand, the electrolyte solution of 1-5) in which toner is dispersed is dropped using a pipette so that the measured concentration is about 5%. adjust. Measurement is performed until the number of measured particles reaches 50,000.

  1-7) The measurement data is analyzed with the dedicated software attached to the apparatus, and the weight average particle diameter (D4) is calculated. The “average diameter” on the analysis / volume statistics (arithmetic average) screen when the graph / volume% is set with the dedicated software is the weight average particle diameter (D4).

(2) Ratio (B / A) of the abundance A of the central element of the charge control agent contained in the toner to the abundance B of the central element of the charge control agent present on the toner surface
A and B are KM Shaker (manufactured by Iwaki Sangyo Co., Ltd.), a fluorescent X-ray analyzer Axios (manufactured by PANalytical), and attached dedicated software “SuperQ ver. 4.0F” for setting measurement conditions and analyzing measurement data ( It is determined from the intensity difference of fluorescent X-rays using a product manufactured by PANalytical.

Specific measurement methods are as follows.
1) About 1 g of toner is placed on a vinyl chloride ring having a ring diameter of 22 mm × 16 mm × 5 mm, and compressed with 100 kgf by a press machine to prepare a sample. The resulting X-ray fluorescence analyzer sample (Axios, measurement conditions will be described later) was measured by, obtaining a net intensity from the central element of the charge control agent with the toner contains ( "I _{B" below).}

  2) Precisely describe 1 g of toner and add 16 g of methanol to a 30 cc vial. After putting the toner into the vial and shaking for 30 minutes under the following conditions, the whole amount of the toner is taken out and dried. At this time, heat is not applied as much as possible, and vacuum drying is performed at about 25 to 40 ° C.

  Here, when the amount of the charge control agent extracted by shaking the shaking time from 10 minutes to 60 minutes is obtained by fluorescent X-ray analysis as follows, it is as shown in FIG. As can be seen from FIG. 4, the amount of charge control agent extracted at a dispersion time of 30 minutes is saturated. This result indicates that the charge control agent that is easily eluted by the dispersion time of up to 30 minutes is eluted, and thereafter, the dissolution rate becomes slow. Moreover, the result of the elution amount at the time of 30 minutes when the surface charge control agent amount is shaken is shown in FIG. In FIG. 5, since the elution amount at 30 minutes corresponds to the amount of charge control agent on the surface, the present inventors considered that the value of 30 minutes represents the amount of charge control agent present on the toner surface.

[Shaking device / conditions]
Device: KM Shaker (manufactured by Iwaki Sangyo Co., Ltd.)
model: V. SX
Shaking conditions: Set speed to 50, shake for 30 minutes, and put about 1 g of the sample obtained by drying on the same vinyl chloride ring as in 1), and compress the sample with 100 kgf with a press machine to make a sample. Using the obtained sample, measurement was performed using a wavelength dispersive X-ray fluorescence analyzer AXIOS (Spectris Co., Ltd.) and extending the X-ray irradiation time until the intensity was in the range of 1.0 to 4.0. Then, the net strength derived from the central element (“I _A ” described later) is obtained. At this time, if the irradiation time is excessively extended, the pellet may be deformed, and accurate data cannot be obtained. For this reason, the maximum measurement time is 15 minutes.

  Rh is used as the anode of the X-ray tube, the measurement atmosphere is vacuum, and the measurement diameter (collimator mask diameter) is 10 mm. Further, a proportional counter (PC) or a scintillation counter (SC) is used depending on the weight of the element.

A ratio B / A of the abundance A of the central element of the charge control agent contained in the toner to the abundance B of the central element of the charge control agent present on the toner surface is obtained by the following equation.
_{B / A = {(I B} -I A) / (I B -M)} × 100
I _A : Net strength of central element of charge control agent in toner after shaking with methanol
I _B : Net strength of central element of charge control agent in toner before methanol shaking M: Net strength of magnetic substance

Note that M in the above equation is obtained as follows.
2 g of the toner is thoroughly examined and 10 g of tetrahydrofuran is put in a 30 ml vial and left overnight to fully dissolve the resin. Further, after shaking the vial for 30 minutes under the above conditions, only the magnetic material in the toner is taken out using a magnet. Thereafter, tetrahydrofuran is added again to the magnetic material and left overnight to sufficiently separate the resin and the magnetic material. After taking out and drying, the value of M is obtained by X-ray fluorescence measurement under the above conditions.

(3) Work function measurement method manufactured by Riken Keiki Co., Ltd .: Using a photoelectron spectrometer AC-2, the work function was measured under the following conditions.
・ Irradiation energy: 4.2 eV to 6.2 eV
・ Light intensity: 300 nW
・ Counting time: 10 seconds / 1 point ・ Anode voltage: 2900V

  The toner carrier is cut into 1 cm × 1 cm to prepare a measurement sample piece. Then, 4.2 to 6.2 eV ultraviolet light is scanned at 0.05 eV intervals from the lower energy level toward the higher energy level. The photoelectrons emitted at this time are measured, and the work function is calculated from the threshold value of the power plot of the quantum efficiency.

  A work function measurement curve obtained by the measurement under the above conditions is shown in FIG. In FIG. 6, the horizontal axis represents excitation energy, and the vertical axis represents the 0.5th power (normalized photon yield) Y of the number of emitted photoelectrons. In general, when the excitation energy value exceeds a certain threshold, the emission of photoelectrons, that is, the normalized photon yield increases, and the work function measurement curve rises rapidly. The rising point is defined as a work function value Wf.

(4) Measurement of surface roughness (RaS, RaB) Surface roughness is measured using a surf coder SE-3500 manufactured by Kosaka Laboratory, based on the surface roughness of JIS B0601 (2001). The measurement conditions were a cutoff of 0.8 mm, an evaluation length of 8 mm (8 mm in the longitudinal direction in the case of a toner carrier), and a feed rate of 0.5 mm / s. In the case of a toner carrier, a total of three positions, that is, a central position of the toner carrier and an intermediate position between the central position and both ends of the coating, and further three positions after rotating the 90 ° toner carrier, and a further 90 ° toner Similarly, after rotating the support, three points were measured in the same manner, and a total of nine points were measured, and the average value was taken. In addition, the toner regulating member was measured at each of the five points, ie, both ends, the central portion, and the middle point thereof, and the average value was obtained.

(5) Measurement of median diameter of charge control agent The volume-based median diameter of the charge control agent used in the present invention is measured according to JIS Z8825-1 (2001). It is.

  As a measuring device, a laser diffraction / scattering particle size distribution measuring device “LA-920” (manufactured by Horiba, Ltd.) is used. The dedicated software “HORIBA LA-920 for Windows (registered trademark) WET (LA-920) Ver. 2.02” attached to LA-920 is used for setting measurement conditions and analyzing measurement data. As the measurement solvent, ion-exchanged water from which impure solids are removed in advance is used.

The measurement procedure is as follows.
1) Attach the batch type cell holder to LA-920.
2) Put a predetermined amount of ion-exchanged water in a batch cell and set the batch cell in a batch cell holder.
3) Stir the inside of the batch cell using a dedicated stirrer tip.
4) Press the “refractive index” button on the “display condition setting” screen and select the file “110A000I” (relative refractive index 1.10).
5) In the “display condition setting” screen, the particle diameter standard is set as the volume standard.
6) After performing warm-up operation for 1 hour or more, optical axis adjustment, optical axis fine adjustment, and blank measurement are performed.
7) Put about 60 ml of ion-exchanged water in a glass 100 ml flat bottom beaker. Among them, as a dispersant, “Contaminone N” (a nonionic surfactant, an anionic surfactant, a 10% by weight aqueous solution of a neutral detergent for washing a pH 7 precision measuring instrument comprising an organic builder, Wako Pure Chemical Industries, Ltd. About 0.3 ml of a diluted solution obtained by diluting the product (manufactured) with ion exchange water about 3 times by mass is added.
8) Two oscillators with an oscillation frequency of 50 kHz are incorporated with the phase shifted by 180 degrees, and an ultrasonic disperser “Ultrasonic Dissipation System Tetora 150” (manufactured by Nikki Bios Co., Ltd.) having an electrical output of 120 W is prepared. Ion exchange water is put in the water tank of the ultrasonic dispersion device, and about 2 ml of Contaminone N is added to the water tank.
9) The beaker of 7) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. And the height position of a beaker is adjusted so that the resonance state of the liquid level of the aqueous solution in a beaker may become the maximum.
10) In a state where the aqueous solution in the beaker of 9) is irradiated with ultrasonic waves, about 1 mg of fatty acid metal salt is added to the aqueous solution in the beaker little by little and dispersed. Then, the ultrasonic dispersion process is continued for another 60 seconds. In this case, the fatty acid metal salt may solidify and float on the liquid surface. In that case, ultrasonic dispersion is performed for 60 seconds after the mass is submerged by shaking the beaker. Moreover, in ultrasonic dispersion, it adjusts suitably so that the water temperature of a water tank may become 10 to 40 degreeC.
11) The aqueous solution in which the fatty acid metal salt prepared in 10) is dispersed is immediately added little by little to the batch type cell while taking care not to introduce bubbles, and the transmittance of the tungsten lamp becomes 90% to 95%. Adjust as follows. Then, the particle size distribution is measured. The median diameter is obtained based on the obtained volume-based particle size distribution data.

(6) Measurement of degree of graphitization d (002) Graphite particles were filled in a non-reflective sample plate, and CuKα rays were applied with a sample horizontal type strong X-ray diffractometer RINT / TTR-II (trade name) manufactured by Rigaku Corporation. An X-ray diffraction chart as a radiation source is obtained. In the present specification, CuKα rays that have been monochromatized with a monochromator are used.

From this X-ray diffraction chart, the interplanar spacing d (002) is obtained from the X-ray diffraction spectrum to determine the peak position of the diffraction line from the graphite (002) plane, and the graphite d (002) is obtained from the flag formula (the following formula (2)). calculate. Here, the wavelength λ of the CuKα ray is 0.15418 nm.
Graphite d (002) = λ / 2sin θ Formula (2)
Measurement condition:
Optical system: Parallel beam optical system Goniometer: Rotor horizontal goniometer (TTR-2)
Tube voltage / current: 50 kV / 300 mA
Measurement method: Continuous method Scan axis: 2θ / θ
Measurement angle: 10 ° to 50 °
Sampling interval: 0.02 °
Scanning speed: 4 ° / min
Divergent slit: Open Divergent longitudinal slit: 10mm
Scattering slit: Opening Light receiving slit: 1.00mm

(7) Measurement of average circularity of toner The average circularity of a magnetic toner is measured using a flow type particle image analyzer “FPIA-3000” (manufactured by Sysmex Corporation) under the measurement and analysis conditions at the time of calibration work.

  A specific measurement method is as follows. First, about 20 ml of ion-exchanged water from which impure solids are removed in advance is put in a glass container. In this, "Contaminone N" (nonionic surfactant, anionic surfactant, 10% by weight aqueous solution of neutral detergent for pH7 precision measuring instrument cleaning, made by organic builder, manufactured by Wako Pure Chemical Industries, Ltd. About 0.2 ml of a diluted solution obtained by diluting the solution with ion exchange water about 3 times by mass. Further, about 0.02 g of a measurement sample is added, and dispersion treatment is performed for 2 minutes using an ultrasonic disperser to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of a dispersion liquid may become 10 to 40 degreeC. As the ultrasonic disperser, a desktop type ultrasonic cleaner disperser (for example, “VS-150” (manufactured by VervoCrea)) having an oscillation frequency of 50 kHz and an electric output of 150 W is used. Ion exchange water is added, and about 2 ml of the above-mentioned Contaminone N is added to this water tank.

  For the measurement, the above-mentioned flow type particle image analyzer equipped with “UPlanApro” (magnification 10 times, numerical aperture 0.40) as an objective lens is used, and the particle sheath “PSE-900A” (manufactured by Sysmex Corporation) is used as the sheath liquid. It was used. The dispersion prepared according to the above procedure is introduced into the flow type particle image analyzer, and 3000 magnetic toner particles are measured in the total count mode in the HPF measurement mode. Then, the binarization threshold at the time of particle analysis is set to 85%, the analysis particle diameter is limited to the equivalent circle diameter of 1.985 μm or more and less than 39.69 μm, and the average circularity of the magnetic toner particles is obtained.

  In the measurement, automatic focus adjustment is performed using standard latex particles (for example, “RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A” manufactured by Duke Scientific) diluted with ion-exchanged water before starting the measurement. Thereafter, it is preferable to perform focus adjustment every two hours from the start of measurement.

  Further, in this embodiment, a flow type particle image analyzer which has been issued a calibration certificate issued by Sysmex Corporation, which has been calibrated by Sysmex Corporation, was used. Measurement is performed under the measurement and analysis conditions when the calibration certificate is received, except that the analysis particle diameter is limited to a circle equivalent diameter of 1.985 μm or more and less than 39.69 μm.

  Hereinafter, the present invention will be described more specifically with reference to production examples and examples, but these do not limit the present invention in any way. In addition, all the parts in the following mixing | blending show a mass part.

<Manufacture of toner carrier 1>
The β-resin was extracted from the coal tar pitch by solvent fractionation, hydrogenated and heavyized, and then the solvent-soluble component was removed with toluene to obtain a mesophase pitch. The mesophase pitch powder is finely pulverized, oxidized in air at about 300 ° C., then heat-treated at 2800 ° C. in a nitrogen atmosphere, and after classification, the volume average particle size is 3.4 μm, the degree of graphitization. Graphitized particles A having p (002) of 0.39 were obtained.

  Next, 100 parts by mass of a resol type phenolic resin using an ammonia catalyst (Dainippon Ink and Chemicals, trade name: J325) in terms of solid content, conductive carbon black (Degussa, trade name: Special Black 4) 40 parts by mass, 60 parts by mass of the graphitized particles A and 150 parts by mass of methanol are mixed and dispersed for 2 hours in a sand mill using glass beads having a diameter of 1 mm as media particles to obtain a coating intermediate M1. It was.

  Furthermore, 50 parts by mass of the resol type phenol resin in terms of solid content, 30 parts by mass of quaternary ammonium salt (Orient Chemical Industries, trade name: Bontron P-51), conductive spherical particles 1 (manufactured by Nippon Carbon Co., Ltd.) , Trade name: Nikabeads ICB0520) and 30 parts by mass of methanol and 40 parts by mass of methanol were mixed and dispersed in a sand mill using glass beads having a diameter of 2 mm as media particles for 45 minutes to obtain paint intermediate J1.

  Next, the obtained paint intermediate M1 and paint intermediate J1 were mixed and stirred to obtain a coating liquid B1.

  Solid content concentration was adjusted to 38% by adding methanol to this coating liquid B1. A cylindrical aluminum tube with an outer diameter of 10 mm and an arithmetic average roughness Ra of 0.2 μm is placed on a turntable, rotated, masked at both ends, and applied while lowering the air spray gun at a constant speed. The conductive resin coating layer was formed by applying the working liquid B1 to the surface of the cylindrical tube. The coating was carried out under the environment of 30 ° C./35% RH and the temperature of the coating solution controlled at 28 ° C. in a thermostatic bath. Subsequently, the conductive resin coating layer was cured by heating at 150 ° C. for 30 minutes in a hot air drying furnace, and thus a toner carrier 1 having an Ra of 0.96 μm was produced. The work function of the conductive resin coating layer of this toner carrier was measured and found to be 4.8 eV. Table 1 shows the composition and physical properties of the toner carrier 1.

<Manufacture of toner carrier 2>
40 parts by weight of the conductive carbon black was replaced with 10 parts by weight of conductive carbon black (product name: # 5500, manufactured by Tokai Carbon Co.), except that the graphitized particles A were changed to 90 parts by weight. A coating liquid B2 was prepared. Using this coating liquid B2, a toner carrier 2 having an Ra of 0.96 μm was prepared in the same manner as described above. The work function of the conductive resin coating layer of this toner carrier was measured and found to be 4.6 eV. Table 1 shows the composition and physical properties of the toner carrier 2.

<Manufacture of toner carrier 3-9>
In the production of the toner carrier 1, toner carriers 3 to 9 were obtained in the same manner as in the production of the toner carrier 1 except that the conductive carbon black and the conductive spherical particles were changed as shown in Table 4. Table 1 shows the compositions and physical properties of the toner carriers 3 to 9.

  In the table, silver particles (SPH02J) are manufactured by Mitsui Kinzoku Co., Ltd., and spherical particles ICB1020 are manufactured by Nippon Carbon Co., Ltd., trade name: Nikabeads ICB1020.

<Production example 1 of magnetic powder>
In ferrous sulfate aqueous solution, l. Caustic soda solution of 0 equivalent or more and 1.1 equivalent or less, P ₂ O _{5 in} an amount of 0.15% by mass in terms of phosphorus with respect to iron element, and 0.50% by mass in terms of silicon with respect to iron element An amount of SiO ₂ was mixed to prepare an aqueous solution containing ferrous hydroxide. The pH of the aqueous solution was 8.0, and an oxidation reaction was performed at 85 ° C. while blowing air to prepare a slurry liquid having seed crystals.

  Subsequently, after adding ferrous sulfate aqueous solution to this slurry liquid so that it may become 0.9 equivalent or more and 1.2 equivalent or less with respect to the initial alkali amount (sodium component of caustic soda), the slurry liquid is maintained at pH 7.6. Then, an oxidation reaction was promoted while blowing air, and a slurry liquid containing magnetic iron oxide was obtained. After filtration, washing and drying, the obtained particles were pulverized to obtain a magnetic powder having a number average particle diameter of 0.22 μm. Table 2 shows the physical properties of the magnetic powder 1 obtained.

<Production Examples 2 to 11 of magnetic powder>
In the production of the magnetic powder 1, the addition amount of P ₂ O _{5 and} the addition amount of SiO ₂ were appropriately adjusted to obtain magnetic powders 2 to 10. Table 2 shows the physical properties of the obtained magnetic powder.

<Manufacture of binder resin 1>
PO addition product of bisphenol A represented by the following formula (A) in the reaction vessel (R represents a propylene group, and the average value of x + y is 2) 50 parts by mass, EO addition of bisphenol A represented by the above formula (A) 20 parts by mass (R represents an ethylene group, the average value of x + y is 2), 18 parts by mass of terephthalic acid, 5 parts by mass of fumaric acid, 5 parts by mass of trimellitic anhydride, and 0.5 parts by mass of dibutyltin oxide These were condensed and polymerized at 220 ° C. to obtain a binder resin 1 which was a polyester resin. This resin had a weight average molecular weight (Mw) of 280,000, an acid value of 24 mgKOH / g, and a Tg of 59 ° C.

<Production Example of Charge Control Agent 1>
Charge control agent 1 manufactured by Orient Chemical Co., Ltd., charge-control agent Bontron S-34 (azo compound as central element Cr) is mechanically pulverized using a mechanical crusher turbo mill (manufactured by Turbo Industry Co., Ltd.). Got. The median diameter was 1.1 μm.

<Production Examples of Charge Control Agents 2-8>
In the production example of the charge control agent 1, as described in Table 3, charge control agents 2 to 9 were produced in the same manner except that the charge control agent used was changed and the median diameter was adjusted. Table 3 shows the charge control agent and median diameter used.

<Production Example of Charge Control Agent 9>
In a pressurizable reaction vessel equipped with a reflux tube, a stirrer, a thermometer, a nitrogen introduction tube, a dropping device and a decompression device, 250 parts of methanol as a solvent, 150 parts of 2-butanone and 100 parts of 2-propanol, and styrene as a monomer 83 parts, 12 parts of butyl acrylate and 4 parts of sodium 2-acrylamido-2-methylpropanesulfonate were added and heated to reflux temperature with stirring. A solution obtained by diluting 0.45 part of t-butylperoxy-2-ethylhexanoate as a polymerization initiator with 20 parts of 2-butanone was added dropwise thereto over 30 minutes, and stirring was continued for 5 hours. -A solution obtained by diluting 0.28 part of butylperoxy-2-ethylhexanoate with 20 parts of 2-butanone was added dropwise over 30 minutes, and the mixture was further stirred for 5 hours to complete the polymerization. Control agent 9 was obtained.

<Manufacture of magnetic toner 1>
Binder resin 1 100 parts by mass Magnetic material 95 parts by mass Polyethylene wax (melting point 115 ° C.) 5 parts by mass Charge control agent 1 3.9 parts by mass The above mixture was premixed with a Henschel mixer and then heated to 120 ° C. The kneaded material was melt-kneaded with an extruder, and the cooled kneaded material was coarsely pulverized with a hammer mill to obtain a coarsely pulverized toner. The obtained coarsely pulverized product was mechanically pulverized and finely pulverized using a mechanical pulverizer turbo mill (manufactured by Turbo Kogyo Co., Ltd.). Fine powder and coarse powder were simultaneously classified and removed from the obtained finely pulverized product by a multi-division classifier (Elbow Jet Classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect. The magnetic toner particles thus obtained had a weight average particle diameter (D4) measured by the Coulter Counter method of 6.3 μm.

To 100 parts of magnetic toner particles, 1.0 part by weight of hydrophobic silica fine powder and 1.1 parts by weight of charge control agent 1 were added to 100 parts by weight of binder resin. Thereafter, using a Henschel mixer (Mitsui Miike Chemical Co., Ltd.), the peripheral speed of the stirring blade was adjusted to 40.0 m / s and mixing was performed for 120 seconds. Thereafter, 1.0 part by mass of hydrophobic silica fine powder was added, and the mixture was further mixed at a peripheral speed of 40.0 m / s for 240 seconds to obtain magnetic toner 1. In the present invention, as a hydrophobic silica fine powder, 100 parts by mass of a silica base material having a primary particle number average particle diameter (D1) of 12 nm and a BET specific surface area of 200 m ² / g is subjected to a surface treatment with 10 parts by mass of hexamethyldisilazane. What was done was used. Further, the amount of charge control agent added at the time of magnetic toner particle production is expressed as the number of internal addition parts, and the amount of charge control agent added to the magnetic toner particles is expressed as the number of external addition parts. Table 4 shows the physical properties and formulation of the magnetic toner 1.

<Manufacture of magnetic toners 2 to 5>
Magnetic toners 2 to 5 were obtained in the same manner as the toner 1 except that the charge control agent 1 was changed to the charge control agent shown in Table 4 in the production of the magnetic toner 1. Table 4 shows the compositions of the magnetic toners 2 to 5 and the physical properties of the toner.

<Manufacture of magnetic toners 6 to 8>
In the production of the magnetic toner 1, the amount of charge control agent for internal and external addition was adjusted as shown in Table 4. The obtained magnetic toner particles were subjected to surface modification with Meteolevo MR-3 type (manufactured by Nippon Pneumatic Kogyo Co., Ltd.) which is a device for modifying the surface of the toner particles by blowing hot air. The conditions during the surface modification were a raw material supply rate of 2 kg / hr, a hot air flow rate of 700 L / min, a discharge hot air temperature of 300 ° C., and adjusted to a desired circularity to obtain magnetic toners 6 to 8. Table 4 shows the compositions of the magnetic toners 6 to 8 and the physical properties of the toner.

<Manufacture of magnetic toner 9>
In the production of the magnetic toner 1, the magnetic toner 9 is prepared in the same manner as in the production of the magnetic toner 1 except that the addition part of the charge control agent 1 is 1.50 parts and the external addition of the charge control agent is not performed. Obtained. Table 4 shows the composition of the magnetic toner 9 and the physical properties of the toner.

<Manufacture of magnetic toners 10 to 20>
In the production of the magnetic toner 1, the production was performed in the same manner as the magnetic toner 1 except that the magnetic powder used and the addition amount thereof were changed as shown in Table 4, and magnetic toners 10 to 20 were obtained. Table 4 shows the compositions of the magnetic toners 10 to 20 and the physical properties of the toner.

<Manufacture of magnetic toner 1 for comparison>
<Manufacture of treated magnetic material>
In a ferrous sulfate aqueous solution, 1.00 equivalent to 1.10 equivalent of caustic soda solution with respect to iron element, and SiO ₂ in an amount of 0.50 mass% in terms of silicon element with respect to iron element are mixed. An aqueous solution containing ferrous hydroxide was prepared. The pH of the aqueous solution was 8.0, and an oxidation reaction was performed at 85 ° C. while blowing air to prepare a slurry liquid having seed crystals.

  Subsequently, the ferrous sulfate aqueous solution was added to this slurry liquid so that it might become 0.90 to 1.20 equivalent with respect to the original alkali amount (sodium component of caustic soda). Thereafter, the slurry liquid was maintained at pH 7.6, and an oxidation reaction was promoted while blowing air to obtain a slurry liquid containing magnetic iron oxide. After filtration and washing, the water-containing slurry was once taken out. At this time, a small amount of water-containing sample was collected and the water content was measured. Next, this water-containing sample is put into another aqueous medium without being dried, stirred and re-dispersed by a pin mill while circulating the slurry, and n-hexyltrimethoxysilane (coupling agent) is stirred and stirred. 1.6 parts by mass was added to 100 parts by mass of magnetic iron oxide, subjected to surface treatment, dried and crushed to obtain a treated magnetic body having a number average particle diameter of 0.21 μm.

<Manufacture of magnetic toner 1 for comparison>
After adding 450 parts by mass of 0.1 mol / L-Na ₃ PO ₄ aqueous solution to 910 parts by mass of ion-exchanged water and heating to 60 ° C., 68 parts by mass of 1.0 mol / L-CaCl ₂ aqueous solution was added. Thus, an aqueous medium containing a dispersion stabilizer was obtained.
-Styrene 78.0 parts by mass-n-Butyl acrylate 22.0 parts by mass-Divinylbenzene 0.6 parts by mass-Treated magnetic material 90.0 parts by mass-Polyester resin (reaction product of terephthalic acid and bisphenol A; weight average molecular weight 30,000) 3.0 parts by mass / polypropylene wax (melting point 80 ° C.) 15.0 parts by mass / charge control agent 2 1.0 parts by mass The above formulation is dispersed and mixed uniformly using a disper blade. Got. This monomer composition was heated to 60 ° C. and dissolved, and then 4 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator.

The monomer composition was charged into the aqueous medium, and granulated by stirring at 12,000 rpm for 10 minutes in a TK homomixer (Special Machine Industries Co., Ltd.) in an N ₂ atmosphere at 60 ° C. Thereafter, the mixture was reacted at 74 ° C. for 4 hours while stirring with a paddle stirring blade, and further heated to 80 ° C. to continue polymerization for 2 hours.

  After completion of the reaction, the suspension was cooled, washed with hydrochloric acid, filtered and dried to obtain comparative amount magnetic toner particles 1.

  1.0 part by mass of hydrophobic silica fine powder and 0.8 part by mass of charge control agent 2 were added to 100 parts by mass of the binder resin with respect to 100 parts of the comparative magnetic toner particles. Thereafter, using a Henschel mixer (Mitsui Miike Chemical Co., Ltd.), the peripheral speed of the stirring blade was adjusted to 40.0 m / s and mixing was performed for 120 seconds. Thereafter, 1.0 part by mass of hydrophobic silica fine powder was added and further mixed for 240 seconds at a peripheral speed of 40.0 m / s to obtain a comparative magnetic toner 1.

<Manufacture of comparative magnetic toners 2, 4 and 6>
Comparative magnetic toners 2, 4 and 6 were obtained in the same manner as in the production of the magnetic toner 6 except that in the production of the magnetic toner 6, the kind of charge control agent, the amount of internal addition and the amount of external addition were adjusted. Table 4 shows the composition and the physical properties of the toner.

<Production of Comparative Magnetic Toners 3, 5, 7>
In the production of the comparative magnetic toner 1, comparative magnetic toners 3, 5, and 7 were obtained in the same manner as in the production of the comparative magnetic toner 1 except that the amount of internal and external addition of the charge control agent was adjusted. . Table 4 shows the composition and the physical properties of the toner.

<Manufacture of Comparative Magnetic Toners 8 to 12>
In the production of the magnetic toner 1, comparative magnetic toners 8 to 12 were obtained in the same manner as the production of the magnetic toner 1 except that the kind of charge control agent, the amount of internal addition, and the amount of external addition were adjusted. Table 4 shows the composition and the physical properties of the toner.

<Examples 1 to 17>
(Image forming device)
Laser Jet P1006 (manufactured by HP) was modified as an image forming apparatus so that 40 sheets could be output per minute. Further, as a developing device, the following was used.

  Next, as the toner regulating member, a 100 μm thick phosphor bronze plate as a supporting member and a 100 μm thick polyphenylene sulfide film (Torelina film type 3000, manufactured by Toray Industries, Inc.) as a blade material were used. Further, the surface roughness (RaB) of the portion where the polyphenylene sulfide surface was abraded and contacted with the magnetic toner carrier was 0.48 μm.

  As shown in FIG. 3, the toner regulating member is fixed to the developing container by sandwiching the free end of one side of the toner regulating member between the two metal plates 13 so as not to wave in the longitudinal direction, and fixing by screwing. On the other hand, the free end side of the toner regulating member was elastically deformed by bringing the tip portion into contact with the surface of the toner carrying member with a predetermined pressure. The contact pressure of the toner regulating member with respect to the toner carrier is 10 N / m, and the distance from the contact position with the toner carrier to the free end is w (mm). The toner carrier 1 was used as the toner carrier, and the magnetic toner 1 was used as the toner. The cartridge (CRG) configuration at this time is CRG1. The cartridge configuration is shown in Table 5. In the table, PPS is the aforementioned polyphenylene sulfide film, PC is a polycarbonate sheet (Panlite sheet PC-2151: manufactured by Teijin Chemicals Limited), PET is a polyethylene terephthalate film (Teijin Tetron Film G2: manufactured by Teijin DuPont Films Limited), and silicone is A silicon rubber sheet (SC50NNS: manufactured by Kureha Elastomer Co., Ltd.) is shown. Moreover, the olefin used the polypropylene film (Novatech PP FW4BT: Nippon Polypro Co., Ltd.). In the same manner as in Example 1, all the regulating members used were those obtained by bonding one of PC, PET, olefin, and silicone to the surface of a 100 μm phosphor bronze plate and taper polishing.

  Under the above conditions, a horizontal line with a printing rate of 4% was tested in an intermittent mode under a normal temperature and humidity environment (23 degrees / 60% RH).

  As a result, it was possible to obtain a good image having high developability, that is, high density and no fogging on the non-image area, before and after the image forming test. There was no problem with the fixing film. Further, when an image output test similar to the above was performed even in a high temperature and high humidity environment, an image having no problem with respect to density, fogging, and fouling of the fixing film was obtained. The evaluation results are shown in Table 6.

<Evaluation>
-Image density The image density formed a solid image portion, and the density of this solid image was measured with a Macbeth reflection densitometer (manufactured by Macbeth).

Fog A white image was output, and the reflectance was measured using a REFECTMETER MODEL TC-6DS manufactured by Tokyo Denshoku. On the other hand, the reflectance of the transfer paper (standard paper) before white image formation was measured in the same manner. A green filter was used as the filter. The fog was calculated from the reflectance before and after the white image output using the following formula.
Fog (reflectance) (%) = reflectance of standard paper (%) − reflectance of white image sample (%)

・ Transferability When the paper is passed for a long time in a high humidity environment, the toner surface is exposed to a large amount of water vapor for a long time while receiving a share. Therefore, transferability can be strictly evaluated.

The transferability of the toner was evaluated by visually observing the image of five continuous black sheets using a developing device after 1500 sheets were passed under a high temperature and high humidity environment.
A: No transfer omission occurred on all 5 sheets.
B: A slight transfer omission was observed.
C: Slight transfer omission was observed on 2 to 4 sheets.
D: Slight transfer omission was observed on all 5 sheets.
E: Clear transfer omission was observed on 1 sheet or more.

-Fixing film stains After the above image output test, solid black was further produced, and the power was turned off when passing through the fixing device to forcibly cause jamming. Thereafter, the image of the fixing device was quickly peeled off, and then a solid white paper was passed, and the fixing film stain was evaluated based on the solid white stain. Thereafter, the same test was performed even in a room temperature and humidity environment.
A: No dirt B: Some slight dirt was seen.
C: Two or more slight stains were observed.
D: Slight dirt was observed as a whole.
E: A clear stain was seen.

<Examples 2 to 17 and Comparative Examples 1 to 5>
An image output test was performed in the same manner as in Example 1 except that the cartridge configuration was changed to CRG 2 to 17 or comparative CRGs 1 to 5. The evaluation results are shown in Table 6.

<Examples 18 to 36, Comparative Examples 6 to 17>
In Example 1, an image output test was performed in the same manner except that the magnetic toners 2 to 20 or the comparative magnetic toners 1 to 12 were used. The evaluation results are shown in Table 6.

1 Electrostatic latent image carrier (photoconductor)
2 Charging roller 3 Magnetic toner carrier 4 Developer 5 Transfer member (transfer roller)
6 Cleaner container 7 Cleaning blade 8 Fixing device 9 Pickup roller 10 Transfer material (paper)
DESCRIPTION OF SYMBOLS 11 Laser generator 12 Magnetic toner control member 13 Metal plate 14 Magnetic toner 15 Stirring member 16 Magnet

Claims (5)

An electrostatic latent image carrier on which an electrostatic latent image is formed, a magnetic toner for developing the electrostatic latent image, a magnetic toner carrier for carrying and transporting the magnetic toner, and the magnetic toner carrier, In the developing device including a regulating member that regulates the magnetic toner,
The magnetic toner carrier has a surface work function value of 4.6 eV or more and 4.9 eV or less,
In the regulating member, the part in contact with the magnetic toner is either polyphenylene sulfide or polyolefin,
The magnetic toner is
i) magnetic toner particles containing a binder resin, magnetic powder, and a charge control agent, and inorganic fine powder,
ii) is negatively charged,
iii) The average circularity is 0.965 or less,
The charge control agent is a compound having, as a central element, an element selected from the group consisting of aluminum, boron, chromium, iron, and zinc, and 1.50 parts by mass or more with respect to 100 parts by mass of the binder resin. 0 parts by mass or less,
When the abundance of the central element of the charge control agent contained in the magnetic toner is A and the abundance of the central element of the charge control agent present on the magnetic toner surface is B, B / A is expressed by the following formula ( A developing device satisfying 1).
0.20 ≦ B / A ≦ 0.60 Formula (1) The surface roughness (RaS) of the magnetic toner carrier is 0.60 μm or more and 1.50 μm or less,
The ratio (RaS / RaB) of the surface roughness (RaB) of the portion of the regulating member that contacts the magnetic toner to the surface roughness (RaS) of the magnetic toner carrier is 1.0 or more and 3.0 or less. The developing device according to claim 1, wherein: The magnetic toner of the measurement magnetic field 795.8 kA / saturation magnetization σs at m is 35Am ² / kg or more, 45Am ² / kg or less, according to claim 1, the residual magnetization σr is equal to or less than 3.0Am ² / kg Or the developing device according to 2; An electrostatic latent image carrier on which an electrostatic latent image is formed, a magnetic toner that develops the electrostatic latent image, a magnetic toner carrier that carries and transports the magnetic toner, and the magnetic toner carrier, Magnetic toner used in a developing device provided with a regulating member that regulates magnetic toner,
The magnetic toner carrier has a surface work function value of 4.6 eV or more and 4.9 eV or less,
In the regulating member, the part in contact with the magnetic toner is either polyphenylene sulfide or polyolefin,
The magnetic toner is
i) a binder resin, magnetic powder, and magnetic toner particles containing a charge control agent; and inorganic fine powder;
ii) is negatively charged,
iii) The average circularity is 0.965 or less,
The charge control agent is a compound having, as a central element, an element selected from the group consisting of aluminum, boron, chromium, iron, and zinc, and 1.50 parts by mass or more with respect to 100 parts by mass of the binder resin. 0 parts by mass or less,
When the abundance of the central element of the charge control agent contained in the magnetic toner is A and the abundance of the central element of the charge control agent present on the magnetic toner surface is B, B / A is expressed by the following formula ( Magnetic toner satisfying 1).
0.20 ≦ B / A ≦ 0.60 Formula (1) A toner regulating member that carries an electrostatic latent image formed on an electrostatic latent image carrier on a magnetic toner carrier provided opposite to the electrostatic latent image carrier and contacts the magnetic toner carrier A developing method for developing with magnetic toner regulated by
The magnetic toner carrier has a surface work function value of 4.6 eV or more and 4.9 eV or less,
In the toner regulating member, the portion in contact with the magnetic toner is either polyphenylene sulfide or polyolefin,
The magnetic toner is
i) magnetic toner particles containing a binder resin, magnetic powder, and a charge control agent, and inorganic fine powder,
ii) is negatively charged,
iii) The average circularity is 0.965 or less,
The charge control agent is a compound having, as a central element, an element selected from the group consisting of aluminum, boron, chromium, iron, and zinc, and 1.50 parts by mass or more with respect to 100 parts by mass of the binder resin. 0 parts by mass or less,
When the abundance of the central element of the charge control agent contained in the magnetic toner is A and the abundance of the central element of the charge control agent present on the magnetic toner surface is B, B / A is expressed by the following formula ( A developing method characterized by satisfying 1).

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