JP2007114752A - Developer, developing method and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing method and an image forming method capable of outputting high-quality images restraining the density reduction, even when high density images are outputted continuously. <P>SOLUTION: The developer is characterized by the fact that the total energy amount is 10 to 100 mJ, when measured with a powder rheometer at a rotor blade tip end speed of 100 mm/sec, at a rotor blade helix angle of -5° and at a ventilation rate of 20 ml/min. A developing method and an image forming method that use the developer are also disclosed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developer, a developing method, and an image forming method for developing an electrostatic latent image in an electrophotographic method or an electrostatic recording method.

  A method of visualizing image information through an electrostatic latent image such as electrophotography is currently used in various fields. In electrophotography, an electrostatic latent image formed on a photoreceptor by a charging and exposure process is developed with a developer containing toner, and visualized through a transfer and fixing process. Developers used for development include a two-component developer composed of a toner and a carrier, and a one-component developer used alone, such as a magnetic toner.

  The two-component development method is the most widely used method. However, the developer deteriorates due to the toner particles adhering to the carrier surface, and the developer cannot be maintained for a long time. A toner density control system to keep the density ratio of the toner constant and a mixing device to mix the newly added toner and developer into the developer are required, which increases the size of the developing device. Cheap.

The one-component toner developing method is classified into a magnetic one-component developing method using magnetic toner and a non-magnetic one-component developing method using non-magnetic toner. Although the non-magnetic one-component development method is suitable for colorization, the force carried on the developer carrier mainly depends only on the charge amount of the developer, and thus there is a problem of causing fogging, in-machine contamination, etc. In the black and white area, a magnetic one-component development method is often used.
In magnetic one-component development, stabilization of charging is important in order to stabilize image density, and attempts have been made to solve the problem by a method such as optimization of external additives (for example, see Patent Document 1).

A magnetic one-component developing type developing device supplies a stable amount of toner to a developer carrying member by providing a stirring member therein. The number of rotations of the stirring member at this time is adjusted according to conditions such as the shape of the stirring member, the number of rotations of the developer carrier, the shape of the developer container, and the capacity.
However, in reality, due to the change in the remaining amount of toner and the output image pattern, the toner is not sufficiently stirred, so the toner supply cannot catch up, and the image is whitened, or conversely, the mechanical stress due to stirring is too great. Therefore, there is a problem that the toner is deteriorated and the image density maintenance is deteriorated.

  In order to solve such a problem, for example, a toner having a specific ratio between the rotation speed of the stirring member and the speed of the developer carrying member and a wettability with a methanol / water mixed solution as a toner is disclosed. (For example, refer to Patent Document 2). However, since the fluidity associated with the stirring property of the stirring member is not controlled in this toner, it is difficult to control a decrease in image density under a stress condition such as continuous output of a high-density image.

Further, in a method of using a plurality of agitating members and controlling the rotational speed of each of them (for example, see Patent Document 3) or a method in which the agitating member is driven intermittently (for example, see Patent Document 4), the developing device is used. There are problems such as enlargement and cost increase.
JP-A-11-143115 JP 2004-163476 A JP 2001-201931 A JP 2001-34051 A

  An object of the present invention is to provide a developing method and an image forming method capable of suppressing a decrease in image density and outputting a high-quality image even during continuous output of high-density images.

  The present invention has been made for the purpose of solving the problems of the prior art in view of the above situation.

<1> Magnetism characterized by a total energy amount of 10 mJ to 100 mJ when measured with a powder rheometer at a tip speed of the rotor blade of 100 mm / sec, an entrance angle of the rotor blade of -5 °, and an air flow rate of 20 ml / min. One component developer.

<2> including toner base particles containing at least a binder resin and magnetic powder, and an external additive externally added to the toner base particles,
<1> characterized in that the external additive includes at least inorganic fine particles having a small particle diameter of 5 to 20 nm and inorganic fine particles having a large particle diameter of 30 to 80 nm. The developer as described.

<3> The developer according to <1> or <2>, wherein the developer is prepared by externally adding the inorganic fine particles having a large particle size before the inorganic fine particles having a small particle size.

<4> The developer accommodated in the developer accommodating portion is agitated by an agitating member, a developer layer is formed on the developer carrying member, and an electrostatic field is applied via the developer layer by applying an electric field. A developing method for developing a latent image on a latent image carrier,
The ratio Va / Vs between the rotation speed Va of the stirring member and the rotation speed Vs of the developer carrying member is 0.05 to 2.
The developing method, wherein the developer is the developer described in any one of <1> to <3>.

<5> A charging step of charging the electrostatic latent image carrier, a latent image forming step of forming an electrostatic latent image on the surface of the charged electrostatic latent image carrier, and a developer containing the electrostatic latent image as a toner And developing the toner image on the latent electrostatic image bearing member, transferring the toner image onto a transfer material to form an unfixed transfer image, and transferring the toner image onto the transfer material. A fixing step of fixing the unfixed transfer image, and an image recording method comprising:
An image forming method using the developing method according to <4> in the developing step.

  According to the present invention, it is possible to provide a developer, a developing method, and an image forming method capable of outputting a high-quality image in which a decrease in image density is suppressed even when a high-density image is continuously output.

<Development method>
In the developing method of the present invention, the developer in the developer container is stirred by a stirring member, a developer layer is formed on the developer carrying member, and an electric field is applied to statically pass through the developer layer. A developing method for developing a latent image on an electrostatic latent image carrier, wherein a ratio Va / Vs between the rotation speed Va of the stirring member and the rotation speed Vs of the developer carrier is 0.05 to 2. The developer is 10 mJ to 100 mJ when the total energy amount of the developer is measured with a powder rheometer at a tip speed of the rotor blade of 100 mm / sec, an entrance angle of the rotor blade of -5 °, and an air flow rate of 20 ml / min. It is characterized by that.
In the case of a one-component developer, since the developer is almost always toner particles, in this specification, developer and toner (or toner particles) may be used synonymously.

When various high-density images are output continuously, the decrease in image density tends to occur because the supply of developer by stirring is insufficient, but the toner supply capability by stirring is greatly affected by the toner state during stirring. It became clear that it was dependent.
In the magnetic one-component development method, since the latent image on the electrostatic latent image carrier is developed by the developer layer formed on the developer carrier, a certain amount of developer must be supplied to the developer carrier. I must. However, since the degree of tightening of the toner powder varies depending on the remaining amount of toner and the toner agitation history associated with the print history, the fluidization behavior of the agitation member to the agitation of the developer depends on the toner state. In contrast, as a result, the amount of developer supplied to the developer carrying member has changed greatly, and it has been difficult to always supply stably.

  In the developing method for developing a latent image on an electrostatic latent image carrier through a developer layer formed on the developer carrier, the present inventors are most stable by a stirring member installed in the developing device. When the developer is stirred and supplied to the developer carrier and the flow characteristics of the developer are reduced so that mechanical stress due to stirring is reduced, the tip speed of the rotor blade in the powder rheometer is 100 mm / sec, It has been clarified that there is a large correlation with the total energy amount when the approach angle of the rotor blade is −5 ° and the air flow rate is 20 ml / min.

Although the mechanism has not been clarified, the state in which the toner is aerated at 20 ml / min is very similar to the state immediately after the toner is agitated by the agitating member. It is considered that the total energy amount correlates with the toner supply ability during ventilation. The toner supply performance can be stabilized by optimizing the total energy amount at this time.
As a result of further investigation, when a magnetic one-component developer having a total energy amount of 10 mJ to 100 mJ is measured under such measurement conditions, a good toner supply property can be stably obtained. It has been found that even when the image is continuously output, the image density is hardly lowered.

FIG. 1 shows an outline of a general developing apparatus 10 used in the developing method of the present invention, but the invention is not limited to this.
The developing device 10 includes a housing 24 including a developer accommodating chamber 18 that accommodates the developer D and a developing roll accommodating chamber 22 that accommodates a developing roll (developer carrying member) 20. The housing 24 is formed with an opening communicating the developer accommodating chamber 18 and the developing roll accommodating chamber 22, and is stirred by the stirring member 26 from the developer accommodating chamber 18 to the developing roll accommodating chamber 22 through the opening. Developer D is supplied.
In the developing method of the present invention, the ratio Va / Vs between the rotational speed Va (rpm) of the stirring member 26 and the rotational speed Vs (rpm) of the developing roll (developer carrier) 20 is 0.05 to 2. It is preferable that it is 0.06-1.8, and it is more preferable that it is 0.07-1.5. If Va / Vs is less than 0.05, the amount of toner supplied may be insufficient, which may lead to a decrease in image density. If Va / Vs is greater than 2, stirring will be excessive, and the toner In order to give excessive stress to the toner, embedding of the external additive added to the toner is promoted, and the image density may decrease with toner consumption.

  An opening 16 that exposes a part of the developing roll 20 to the outside is provided above the developing roll storage chamber 22, and the developing roll 20 serves as a photosensitive drum (electrostatic latent image carrier) 12. Opposite to. An area where the developing roll 20 and the photosensitive drum 12 face each other is a developing area, and the developer D is carried and conveyed by the developing roll 20 to the developing area. A power source (not shown) for applying a developing bias to the developing roll 20 is connected.

  The developing roll 20 includes a magnet roll 28 that is fixed so as not to rotate and in which a plurality of magnetic poles 28 </ b> A to 28 </ b> D (four poles in this embodiment) are alternately arranged. Is provided with a non-magnetic cylindrical developing sleeve 30 that rotates in one direction (direction B in FIG. 2).

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

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

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

  The shape of the stirring member 26 is not limited as long as the stirring property of the toner can be obtained, but a member in which a resin sheet such as PET is attached to a support member serving as a rotation shaft can be preferably used.

In the developing device having the above configuration, the behavior of the magnetic one-component developer of the present invention during development will be described.
The developer is agitated and conveyed by rotation of the agitating member 26 in the developer accommodating chamber 18, and can be supplied from the developer accommodating chamber 18 to the developing roll accommodating chamber 22 through the opening. After the developer adheres to the surface of the developing sleeve 30 by the magnetic force of the magnet roll 28, the layer thickness is regulated by the protruding amount of the layer forming blade (layer regulating member) 32 and the contact pressure, and the developer is triboelectrically charged. The developer that is frictionally charged and conveyed onto the sleeve moves to the electrostatic latent image carrier (photosensitive drum) 12 according to the amount of charge and is developed.
As for the developer, the portion corresponding to the electrostatic latent image on the developer carrying member is consumed, but the other portions are not consumed, and the developer in the developing roll storage chamber 22 is newly added to form a layer. It passes through the blade 32 and is again layered.
Developers that are not within the range of the total energy amount described above are unstable in supply to the developer carrier and are liable to cause a reduction in image density.

  The magnetic one-component developer according to the present invention is measured with a powder rheometer when the total energy amount of the developer is measured at a tip speed of the rotor blade of 100 mm / sec, an entrance angle of the rotor blade of -5 °, and an air flow rate of 20 ml / min. It is characterized by being 10 mJ-100 mJ.

  Since the developer having such a total energy amount exhibits a stable fluidity regardless of the state of the toner, the developer is smoothly supplied onto the developer carrier.

The developer fluidity measurement using a powder rheometer will be described in more detail.
When measuring the fluidity of particles, it is more influenced by many factors than when measuring the fluidity of liquids, solids, or gases. It is difficult to specify the exact fluidity of the particles. In addition, even if a factor to be measured (for example, particle size) is determined to specify fluidity, the factor actually has little effect on fluidity or only in combination with other factors. The significance of measuring the factor may arise, and even determining the measurement factor is difficult.
Furthermore, the fluidity of the powder varies significantly depending on external environmental factors. For example, in the case of a liquid, even if the measurement environment changes, the fluctuation range of the fluidity is not so large, but the fluidity of the particles is greatly influenced by external environmental factors such as humidity and the state of the flowing gas. fluctuate. It is not clear which measurement factors are affected by these external environmental factors, so even if measured under strict measurement conditions, the reproducibility of the measured values obtained is actually poor. is there.

  In addition, for the fluidity of toner particles in the developing tank, the angle of repose and the bulk density have been used as indices, but these physical property values are indirect to the fluidity, and the fluidity is quantified. It was difficult to manage.

  However, since the powder rheometer can measure the total amount of energy applied from the developer to the rotor blades of the measuring machine, it can be obtained as a sum of the factors attributable to fluidity. Therefore, the powder rheometer determines the items to be measured for the developer obtained by adjusting the surface physical property values and particle size distribution as in the past, and finds and measures the optimum physical property values for each item. Without being able to measure the fluidity directly. As a result, it is possible to determine whether it is suitable as a developer used for developing an electrostatic image only by confirming whether it falls within the above numerical range with a powder rheometer. Such production management of the developer is a method that is extremely suitable for practical use as compared with the conventional method of managing with the indirect value with respect to keeping the fluidity of the developer constant. Moreover, it is easy to make measurement conditions constant, and the reproducibility of measured values is high. That is, the method for specifying the fluidity by the value obtained by the powder rheometer is simple, accurate and highly reliable as compared with the conventional method.

  As described above, in order to prevent image density unevenness from occurring due to the non-uniform charge amount of the developer on the developer carrier, in the powder rheometer, the tip speed of the rotary blade is 100 mm / sec, approach angle of rotary blade -5 °, air flow rate 20 ml / min. When the total energy amount of the developer is measured in (1), it is extremely effective that the total energy amount is 10 mJ to 100 mJ. The developer within this range ensures fluidity stability in the developing device, the developer is sufficiently supplied onto the developer carrier, and the image density is maintained even in continuous output of high-density images. Decline can be prevented.

When the measured value with a powder rheometer is lower than 10 mJ, the fluidity is too high, so that the developer is ejected from the vicinity of the developing carrier and the inside of the image forming apparatus may be stained. Moreover, it is not practical from the viewpoint of productivity. On the other hand, when it exceeds 100 mJ, the supply of the developer by the stirring member becomes insufficient, and the decrease in image density, which is the subject of the present invention, cannot be suppressed.
More preferably, the said total energy amount is the range of 20-90 mJ, More preferably, it is the range of 30-80 mJ.

Next, a measurement method using a powder rheometer will be described.
The powder rheometer is a fluidity measuring device that directly measures fluidity by simultaneously measuring rotational torque and vertical load obtained by rotating a rotating blade spirally in packed particles. By measuring both the rotational torque and the vertical load, the fluidity including the characteristics of the powder itself and the influence of the external environment can be detected with high sensitivity. In addition, since the measurement is performed with the particle filling state kept constant, data with good reproducibility can be obtained.

  In the present invention, measurement is performed using FT4 manufactured by freeman technology as a powder rheometer. In order to eliminate the influence of temperature and humidity before the measurement, a developer that is left at a temperature of 22 ° C. and a humidity of 50% RH for 8 hours or more is used.

First, the developer is filled in a split container with an inner diameter of 50 mm (a cylinder with a height of 51 mm placed on a 160 mL container with a height of 89 mm so that it can be separated vertically) with an amount exceeding 89 mm in height. To do.
After the developer is filled, the sample is homogenized by gently stirring the filled developer. This operation will be called conditioning in the following.

In conditioning, the rotating direction that does not receive resistance from the developer so as not to stress the developer in the filled state (depending on the inclination direction of the blade of the rotor blade, but with the rotor blade shown in FIG. Gently agitate the rotor blades (counterclockwise) to remove most of the excess air and partial stress and make the sample homogeneous. Specific conditioning conditions are agitation at a tip angle of 60 mm / sec with an approach angle of 5 °.
At this time, the propeller-type rotor blades move downward simultaneously with the rotation, so that the tip draws a spiral, and the angle of the spiral path drawn by the propeller tip at this time is called the entry angle.

  After repeating the conditioning operation four times, the container upper end of the split container is gently moved, and the developer inside the vessel is scraped off at a height of 89 mm to obtain a developer filling the 160 mL container. Such an operation is performed because it is important to always obtain a powder having a constant volume in order to stably obtain the total energy of the present invention.

  The developer thus obtained is transferred to a 200 mL container having an inner diameter of 50 mm, a height of 140 mm, and a mesh bottom plate that can be vented. After the developer was transferred to the 200 mL container, conditioning was further performed 5 times, and then the inside of the container was raised from the bottom to a height of 110 mm to 10 mm at an entrance angle of -5 ° while flowing air at an air flow rate of 20 ml / min. Rotating torque and vertical load when rotating at a tip speed of 100 mm / sec while moving are measured. The direction of rotation of the propeller at this time is the reverse direction to the conditioning (clockwise as viewed from above).

  Here, the measurement is performed while flowing air at 20 ml / min in order to more closely approximate the flow state of the developer in the developing device. The air flow rate at 20 ml / min is considered to reproduce the flow state immediately after the developer is stirred by the stirring member. In the FT4 manufactured by freeman technology, the inflow state of the air flow rate is controlled.

2A and 2B show the relationship between the rotational torque or the vertical load with respect to the height H from the bottom surface. FIG. 3 shows the energy gradient (mJ / mm) with respect to the height H obtained from the rotational torque and the vertical load. The area (shaded portion in FIG. 3) obtained by integrating the energy gradient in FIG. 3 is the total energy amount (mJ). In the present invention, a total energy amount is obtained by integrating a section from 10 mm to 110 mm in height from the bottom surface.
In the present invention, in order to reduce the influence of errors, the average value obtained by performing this conditioning and energy measurement operation cycle five times is defined as the total energy amount (mJ) defined in the present invention.

  As the rotor blade, a two-blade propeller type φ48 mm diameter blade shown in FIG. 4 manufactured by freeman technology is used.

In order to make the total energy amount of the developer (toner particles) measured within the above conditions within the above range, the shape of the toner particles, the amount of wax, the particle size distribution, the type of additive and the amount added The method of adjusting is mentioned, It is also suitable to use combining these methods.
In the present invention, as a method for obtaining the total energy amount as defined above, as external additives, small particle size inorganic fine particles having a number average particle size of 5 to 20 nm and large particle size inorganic fine particles having a number average particle size of 30 to 80 nm are used. At least two of these are used in combination. Furthermore, it is preferable that the developer is prepared by externally adding inorganic fine particles having a large particle diameter before the inorganic fine particles having a small particle diameter.
The developer (toner particles) according to the present invention can be obtained by referring to the following specific composition and production method.

Hereinafter, the magnetic one-component developer of the present invention will be described in detail.
The magnetic one-component developer of the present invention is not particularly limited as long as it has the above total energy amount, and a known technique can be appropriately applied.

A suitable developer includes toner base particles containing at least a binder resin and magnetic powder, and an external additive externally added to the toner base particles. The external additive has a number average particle size of 5 It is a case containing at least two kinds of inorganic fine particles having a small particle diameter of ˜20 nm and inorganic fine particles having a large particle diameter of 30 to 80 nm, and more preferably, the inorganic fine particles having a large particle diameter are small in size. This is the case of a developer prepared by externally adding before the inorganic fine particles having a particle size.
Hereinafter, the composition and physical properties of the toner particles will be described.

[Binder resin]
As the binder resin contained in the toner particles, a known resin that can be used for the toner particles can be appropriately selected. Specifically, for example, styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isobutylene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate, acrylic acid Esters of α-methylene aliphatic monocarboxylic acids such as methyl, ethyl acrylate, butyl acrylate, octyl acrylate, dodecyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate , Homopolymers and copolymers of vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, etc. As typical binder resins, polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, Mention may be made of styrene-maleic anhydride copolymers, polyethylene, polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, and modified rosin.
Among these, styrene- (meth) acrylic acid ester copolymer resins and polyester resins are preferably used.

The molecular weight of the binder resin varies depending on the type of resin, but the weight average molecular weight Mw is preferably 10,000 to 500,000, more preferably 15,000 to 300,000, and 20,000. More preferably, it is -200,000. The number average molecular weight Mn is preferably 2,000 to 30,000, more preferably 2,500 to 20,000, and still more preferably 3,000 to 15,000.
The values of the weight average molecular weight and the number average molecular weight are those measured using gel permeation chromatography (GPC). GPC uses HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation), and column uses two TSKgel and SuperHM-H (manufactured by Tosoh Corporation, 6.0 mm ID × 15 cm). THF (tetrahydrofuran) is used. As experimental conditions, the sample concentration is 0.5 mass%, the flow rate is 0.6 ml / min, the sample injection amount is 10 μl, the measurement temperature is 40 ° C., and an IR detector is used.

  The glass transition temperature of the binder resin is preferably 40 ° C. to 80 ° C., and preferably 45 ° C. to 75 ° C. from the viewpoints of preventing deterioration of fluidity in a high temperature environment and achieving low temperature fixability. More preferred.

  The glass transition point (Tg) refers to a value obtained by measurement under a temperature rising rate of 10 ° C./min using a differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-50). The glass transition point is the temperature at the intersection of the extension line of the base line and the rising line in the endothermic part.

[Magnetic powder]
As the magnetic powder, known magnetic materials, for example, metals such as iron, cobalt, nickel and alloys thereof, Fe ₃ O ₄ , γ-Fe ₂ O ₃ , metal oxides such as cobalt-added iron oxide, MnZn ferrite, Various ferrites such as NiZn ferrite, magnetite, hematite and other powders can be used, and the surface thereof is treated with a surface treatment agent such as a silane coupling agent or titanate coupling agent, and inorganic compounds such as silicon compounds and aluminum compounds Those coated with a system material or those coated with a polymer may be used.
The mixing ratio of the magnetic powder is preferably in the range of 35 to 55% by mass, more preferably in the range of 40 to 50% by mass with respect to the entire developer particles. When the magnetic powder is less than 35% by mass, the binding force of the developer by the magnet in the developer carrying body is reduced, and the problem of developer scattering and fogging occurs. On the other hand, when it exceeds 55 mass%, there is a problem that the image density is lowered.

  A magnetic powder having a volume average particle size of about 0.05 to 0.35 μm is preferably used from the viewpoint of dispersibility in the binder resin.

The toner base particles can be produced according to a known production method. There is no restriction | limiting in particular as said manufacturing method, According to the objective, it can determine suitably.
For example, after pre-mixing a binder resin and a colorant, if necessary, a charge control agent, etc., melt-kneading in a kneader, pulverizing after cooling, and using a vibration sieving machine or a wind sieving machine as described above It can be manufactured using a kneading and pulverizing system that performs classification.
Further, it can be produced by a wet spheronization method, a suspension granulation method, a suspension polymerization method, an emulsion polymerization aggregation method or the like.

[External additive]
The developer of the present invention contains an external additive in the toner particles in order to improve transferability, fluidity, cleaning properties, chargeability controllability, particularly fluidity. The external additive refers to fine particles that adhere to the surface of the toner core particles.
In the present invention, as the external additive, it is preferable to use at least two kinds of inorganic fine particles having a number average particle diameter of 5 to 20 nm and large inorganic particles having a number average particle diameter of 30 to 80 nm in combination.
By using two types of external additives with different primary particle sizes, fine irregularities on the surface of the toner particles are controlled, and the adhesion between the toner particles and the ease of rolling of the toner particles are adjusted. The total amount of energy in can be controlled.

  Examples of the inorganic fine particles to be added include silica, aluminum oxide, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, and diatomaceous earth. , Cerium chloride, bengara, chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, magnesium carbonate, zirconium oxide, silicon carbide, silicon nitride, calcium carbonate, barium sulfate and other metal oxides and ceramic particles, either alone or in combination Can be used.

  Furthermore, organic fine particles may be externally added, for example, vinyl polymers such as styrene polymers, (meth) acrylic polymers, ethylene polymers, ester-based, melamine-based, amide-based, allyl phthalate-based polymers. Examples thereof include various polymers such as fluorinated polymers such as vinylidene fluoride, and fine particles composed of higher alcohols such as unilin.

  In particular, the inorganic fine particles preferably include at least one selected from silica fine particles, aluminum oxide, titanium oxide, and zinc oxide, more preferably include silica and titanium oxide, and include silica. More preferably.

  The number average particle size of the small particle size inorganic fine particles is preferably 5 to 20 nm, more preferably 5 to 16 nm, and still more preferably 5 to 14 nm. When the number average particle diameter of the inorganic fine particles is less than 5 nm, the fine particles are embedded in the toner particle surface and do not contribute to the fluidity of the toner particles. On the other hand, when the thickness exceeds 20 nm, the toner particles are easily released from the toner particles, not only contributing to the fluidity of the toner particles, but also free external additives are deposited in the developing device.

  The number average particle size of the large particle size inorganic fine particles is preferably 30 to 80 nm, more preferably 30 to 70 nm, and still more preferably 35 to 65 nm. When the volume average particle size of the inorganic fine particles is less than 30 nm, the particle size difference from the small-diameter external additive becomes small, and it becomes difficult to control the total energy amount in the powder rheometer. On the other hand, when the thickness exceeds 80 nm, the adhesion to the toner is lowered, so that it is difficult to maintain the externally added structure, and it is difficult to maintain the toner supply property.

  The number average particle diameter of the external additive can be measured by observing a sample in which the external additive is embedded in an epoxy resin with a transmission electron microscope (TEM).

The amount of the external additive used as a whole is preferably 0.5% by mass to 10% by mass, more preferably 0.6% by mass to 8% by mass with respect to the toner base particles. More preferably, it is 8 mass%-6 mass%. If it is less than 0.5% by mass, the fluidity of the toner is insufficient, and it is difficult to control the total energy amount of the air flow rate of 20 ml / min in the powder rheometer to 10 to 100 mJ. In addition, the chargeability of the toner becomes insufficient, which tends to cause a decrease in image density. If the amount is more than 10% by mass, the free amount of the external additive is increased, so that problems such as contamination of the photosensitive member and the charging member are likely to occur.
Moreover, it is preferable that the surface coverage calculated by following formula (1) is 50 to 600%, 60 to 550% is more preferable, and 70 to 500% is still more preferable. In the case of such a surface coverage, it is easy to prepare the toner particles so as to be within the total energy amount range of the powder rheometer according to the present invention.

In the above formula, D _N represents the average particle diameter (μm) of the toner core particles, ρ _N represents the density of the toner core particles, D _a represents the average particle diameter (nm) of the external additive, and ρ _a The density of the external additive is represented, and X represents the addition amount (% by mass) of the external additive.

  The large particle size inorganic fine particles are preferably 40 to 800 parts by mass, more preferably 50 to 700 parts by mass, and 60 to 600 parts by mass with respect to the small particle size inorganic fine particles (100 parts by mass). More preferably it is. If the amount is less than 40 parts by mass, it is insufficient to control the unevenness of the surface, and it is difficult to control the total energy amount to 100 mJ or less. Prone to contamination.

  The inorganic fine particles of the external additive are desirably surface-treated in advance. This surface treatment improves the powder fluidity of the toner particles and is effective for the environmental dependence of charging. The surface treatment can be performed by immersing inorganic fine particles in the treatment agent. The treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents, and the like. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.

  As the silane coupling agent, for example, any one of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyl Triethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltriethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N- (trimethylsilyl) ) Urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysila , Γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyl Examples include trimethoxysilane and γ-chloropropyltrimethoxysilane.

  As the surface treatment method of the external additive fine particles, for example, a treatment agent mixed and diluted with a solvent such as tetrahydrofuran, toluene, ethyl acetate, methyl ethyl ketone, acetone or the like is dropped on fine particles that are forcibly stirred with a blender or the like, or sprayed. Or after mixing, washing and filtering as necessary, drying by heating, crushing the agglomerates with a blender, mortar, etc. After leaching into the solution, drying, or dispersing fine particles in water to form a slurry, and then dropping the treatment agent solution, then allowing the fine particles to settle, drying by heating and crushing. A conventionally known method such as a method of directly spraying the treatment agent can be used.

The external additive can adhere to or adhere to the surface of the developer particles by applying a mechanical impact force together with the developer particles using a sample mill or a Henschel mixer.
In the present invention, it is preferable to prepare the developer by externally adding the inorganic fine particles having a large particle diameter before the inorganic fine particles having a small particle diameter. By first externally adding large particle size inorganic fine particles, the small particle size inorganic fine particles cover the toner particle surface and simultaneously covering the large particle size external additive surface, thereby controlling the fine irregularities on the outermost surface of the toner. Thereby ensuring the desired fluidity. As long as the order of addition is the small inorganic particle after the large particle, the addition time is not particularly limited.

[Other additives]
In addition to the above composition, known materials used in the developer can be added as appropriate to the magnetic one-component developer of the present invention.

(wax)
The developer of the present invention preferably contains a wax for the purpose of improving offset resistance. Examples of the wax used in the present invention include paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, and the like. Derivatives include oxides, polymers with vinyl monomers, graft modified products, and the like. In addition, alcohols, fatty acids, plant waxes, animal waxes, mineral waxes, ester waxes, acid amides, and the like can be used.
Specifically, hydrocarbon waxes such as low molecular weight polypropylene and low molecular weight polyethylene, microcrystalline wax, silicone resin, rosins, ester wax, rice wax, carnauba wax, Fischer-Tropsch wax, montan wax, candelilla wax, etc. Is mentioned.

The ratio of the wax is preferably in the range of 0.1 to 10% by mass, more preferably in the range of 1 to 8% by mass with respect to the whole toner particles.
If the content of the wax agent is less than the above lower limit value, the toner release performance may be reduced and offset may occur. On the other hand, if the content exceeds the upper limit value, the toner charging performance is deteriorated or the heat storage performance is deteriorated. Decrease may occur and each is not preferable.

(Coloring agent)
The developer of the present invention may contain a colorant in order to adjust the color tone. There is no restriction | limiting in particular as said coloring agent, The coloring agent known per se can be mentioned, According to the objective, it can select suitably. Examples of the colorant include carbon black, lamp black, Dupont Oil Red, Orient Oil Red, Rose Bengal, C.I. I. Pigment Red 5, 112, 123, 139, 144, 149, 166, 177, 178, 222, 48: 1, 48: 2, 48: 3, 53: 1, 57: 1, 81: 1, C.I. I. Pigment orange 31, 43, quinoline yellow, chrome yellow, C.I. I. Pigment Yellow 12, 14, 17, 93, 94, 97, 138, 174, 180, 188, ultramarine blue, aniline blue, calcoyl blue, methylene blue chloride, copper phthalocyanine, C.I. I. Pigment Blue 15, 60, 15: 1, 15: 2, 15: 3, C.I. I. Pigment Green 7 and malachite green oxalate, nigrosine dye, and the like can be used, and these can be used alone or in combination. These may have been subjected to flashing dispersion processing in advance.

(Charge control agent)
Various substances can be added for the purpose of charge control. For example, high molecular acids such as fluorosurfactants, salicylic acid complexes, iron dyes such as iron complexes, chromium dyes such as chromium complexes, and copolymers containing maleic acid as a monomer component, quaternary An azine dye such as ammonium salt and nigrosine may be added in the range of 0.1 to 10.0% by mass in the developer.

[Physical properties of developer]
(Volume average particle diameter of toner particles)
The volume average particle size of the toner particles is preferably 4 μm to 12 μm, more preferably 4.5 μm to 10 μm, and still more preferably 5 μm to 9 μm. When the volume average particle size of the toner particles is less than 4 μm, the fluidity is remarkably lowered, so that the developer layer is not sufficiently formed by the layer regulating member or the like, and the image may be fogged or dirtied. On the other hand, if it exceeds 12 μm, the resolution is lowered and a high-quality image may not be obtained, or the charge amount per developer unit weight is lowered, and the layer formation maintenance property of the developer layer is lowered, Fog and dirt may occur in the image.

As a method for measuring the volume average particle diameter of the toner particles, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% by weight aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, as a dispersant, and this is added to the electrolytic solution 100. Added in ~ 150 ml. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute. Using the Coulter Counter TA-II type, an aperture having an aperture diameter of 100 μm is used. The particle size distribution of particles in the range of 64 μm is measured. The number of particles to be measured is 50,000.
For the particle size range (channel) obtained by dividing the obtained particle size distribution, the volume cumulative distribution is subtracted from the small particle size side, and the particle size that becomes 50% cumulative is _defined as the volume average particle size D _50v .

(Particle size distribution of toner particles)
The preferred particle size distribution of the toner particles is when the proportion of toner particles having a particle size of 4 μm or less is 45% by number or less, more preferably 40% by number or less, and even more preferably 35% by number or less.
Similarly to the determination of the volume average particle diameter D _50v , the particle diameter that is 84% cumulative when the volume cumulative distribution is subtracted from the small particle diameter side is D _84v, and the number cumulative distribution is calculated from the small particle diameter side. When the particle diameter that is 16% is D _16p and the particle diameter that is 50% is D _50p (number average particle diameter), the coarse particle size distribution index = D _84v / D _50v is 1.35 or less. It is preferable that it is 1.30 or less. The fine particle size distribution index = D _50p / D _16p is preferably 1.45 or less, and more preferably 1.40 or less.

  In order to obtain toner particles having such a particle size distribution, the toner particle size can be adjusted to a desired particle size distribution by using a gravity classifier, a centrifugal classifier, an inertia classifier, or a sieve.

  When the particle size distribution of the toner particles is wider than the above range, the total energy amount by the powder rheometer described above tends to be out of the specified range.

(Toner particle shape factor)
The shape of the toner particles is preferably controlled in order to obtain the total energy amount according to the present invention. The shape factor SF1 of the toner particles represented by the following formula (2) is preferably 135 or less, and more preferably 130 or less.

Formula (2): SF1 = (ML ² / A) × (π / 4) × 100

In the above formula (2), ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.
The toner shape factor SF1 is obtained by taking an optical microscope image of toner particles dispersed on a slide glass into a Luzex image analyzer through a video camera, obtaining a maximum length and a projected area of 1000 or more toners, and using the above equation (2). It is obtained by calculating and obtaining the average value. SF1 is considered to be a true sphere as it approaches 100, and becomes larger as the numerical value increases.

  The toner particles having the above toner shape factor are subjected to heat treatment after pulverization and classification, treatment by mechanical impact force, etc. to control the spheroidization of the toner shape, or by applying a wet production method such as an emulsion aggregation method. Obtainable.

<Image forming method>
The image forming method of the present invention comprises at least a charging step for charging the electrostatic latent image carrier, a latent image forming step for forming an electrostatic latent image on the surface of the charged electrostatic latent image carrier, and the electrostatic latent image. A development step of developing the image with a developer containing toner to form a toner image on the electrostatic latent image carrier, and a transfer step of transferring the toner image onto a transfer material to form an unfixed transfer image. A fixing step of fixing the unfixed transfer image transferred onto the transfer material. The developer used in the development process is a developer having the above total energy amount.

  In the image forming method of the present invention, known techniques can be appropriately applied to the charging step, the latent image forming step (exposure step), and the transfer step. Further, in addition to these steps, a cleaning step for removing the electrostatic latent image carrier after the transfer step, a charge eliminating step, and the like may be performed.

  In the developing step, as in the developing apparatus shown in FIG. 1, the developer is transferred to the surface of the developer carrying member while being stirred by the stirring member. Further, the developer carrying member carrying the developer rotates to face the electrostatic latent image carrying member, and the developer is conveyed to the image carrying member for development.

FIG. 5 shows an example of an image forming apparatus used in the image forming method of the present invention. In FIG. 5, the electrostatic latent image carrier 12, the charging means 40 for charging the electrostatic latent image carrier 12, and the charged electrostatic latent image carrier 12 are exposed to expose the surface of the electrostatic latent image carrier 12. A latent image forming means (exposure means) 42 for forming an electrostatic latent image on the surface, developing means 10 for developing the electrostatic latent image with a developer to form a toner image, and carrying the toner image with an electrostatic latent image. The image forming apparatus preferably includes a transfer unit 44 that transfers the recording material from the body 12 to a recording material, and a fixing unit 46 that fixes an unfixed transfer image transferred onto the recording material. Further, a cleaning means 48 may be provided.
Each of these constituent members, that is, electrostatic latent image carrier (electrophotographic photosensitive member, photosensitive drum) 12, charging means 40, latent image forming means 42, developing means 10, transfer means 44, fixing means 46, cleaning means. Further, the static elimination means (not shown) and the like are not particularly limited in the present invention, and any conventionally known configuration can be used without any problem. The developing means 10 shown in FIG. 5 is the developing device shown in FIG.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

<Measuring method of various characteristics>
First, methods for measuring physical properties of developers and the like used in Examples and Comparative Examples will be described.

-Shape factor-
An optical microscope image of the toner particles dispersed on the nuclear slide glass is taken into an image analyzer (LUZEXIII, manufactured by Nireco) through a video camera. From the maximum length and area for 1000 particles, the above formula (2) for each particle is obtained. SF1 was calculated and the average value was obtained

-Volume average particle size, particle size distribution-
The particle size was measured using a Coulter counter TA-II type (manufactured by Beckman-Coulter) as the measuring device and ISOTON-II (manufactured by Beckman-Coulter) as the electrolyte.

  As a measuring method, 10 mg of a measurement sample was added to 2 ml of a 5% by weight aqueous solution of a surfactant and sodium alkylbenzenesulfonate as a dispersant, and this was added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute. Using the Coulter Counter TA-II type, an aperture having an aperture diameter of 100 μm is used. The particle size distribution of particles in the range of 64 μm was measured. The number of particles to be measured was 50,000.

For the divided particle size range (channel), a cumulative distribution is drawn from the small diameter side for each of the volume and number, and the cumulative volume particle size that is 16% cumulative in volume with respect to all toner particles. _The cumulative number particle size that is 16% and the cumulative number is 16% is defined as D _16p . Similarly, the particle size that is 50% cumulative in volume is defined as the volume average particle size D _50v , and the particle size that is cumulative 50% in number is defined as the number average particle size D _50p . Similarly, a cumulative volume particle size that is 84% cumulative is defined as D _84v , and a cumulative number particle size that is 84% cumulative is defined as D _84p . The volume average particle diameter is the D _50v .
For the toner particles, the proportion of particles having a particle size of 4 μm or less was determined from the particle size distribution obtained above.

-Measurement of molecular weight distribution-
The molecular weight distribution of the resin of the toner was performed under the following conditions.
Tosoh Corporation HLC-8120GPC, SC-8020 apparatus was used, TSK gei, SuperHM-H (6.0 mmID × 15 cm) was used as a column, and THF (tetrahydrofuran) was used as an eluent. As measurement conditions, the sample concentration was 0.5% by mass, the flow rate was 0.6 ml / min, the sample injection amount was 10 μl, the measurement temperature was 40 ° C., and the measurement was performed using an IR detector.
The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: A-500, F-1, F-10, F-80, F-380, A-2500, F-4, F-40, F-128. , F-700 was prepared from 10 samples. The data collection interval in the sample analysis was 300 ms.

-Measurement of glass transition temperature-
The glass transition point (Tg) of the binder resin was determined by measurement using a differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-50) under a temperature increase rate of 10 ° C./min. In addition, the glass transition point was made into the temperature of the intersection of the extended line of the base line in a heat absorption part, and a rising line.

-Measurement of weight average molecular weight-
Measurement was performed by the method described above.

<Preparation of base toner>
(Preparation of base toner (1))
Binder resin: Styrene / n-butyl acrylate (monomer mass ratio = 82/18) resin (Mw = 140,000, Tg = 59 ° C.) 46.5% by mass
・ Magnetite (trade name: MTH009F, manufactured by Toda Kogyo Co., Ltd.) ... 50% by mass
・ Polypropylene wax: 2.5% by mass
(Product name: Viscol 550-P, manufactured by Sanyo Chemical Industries)
・ Negative charge control agent (Fe-containing azo dye) ・ ・ ・ 1.0% by mass
(Product name: T-77, manufactured by Hodogaya Chemical Co., Ltd.)

The above composition was powder-mixed with a Henschel mixer and heat-kneaded with an extruder with a set temperature of 150 ° C. to obtain a kneaded product (1). After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a volume average particle diameter D _50v of 5.7 μm.
Further, this pulverized product was classified and subjected to spheronization using a Nobilta manufactured by Hosokawa Micron Co., Ltd., and a toner having D _50v : 6.1 μm, D _84v / D _50v : 1.25, D _50p / D _16p : 1.27. Mother particles (1) were obtained. The average toner shape factor of this toner was 128.

(Preparation of base toner (2))
A kneaded product (2) was prepared in the same manner as the base toner (1), and after cooling, coarsely pulverized and finely pulverized to obtain a pulverized product having a volume average particle diameter D _50v of 5.2 μm. Further, this pulverized product was classified and subjected to spheronization using Nobilta manufactured by Hosokawa Micron Co., Ltd., and D _50v : 5.6 _μm , D _84v / D _50v : 1.24, and D _50p / D _16p : 1.24 toner. Mother particles (2) were obtained. The average toner shape factor of this toner was 124.

(Preparation of base toner (3))
Binder resin: Styrene / n-butyl acrylate (monomer mass ratio = 82/18) resin (Mw = 140,000, Tg = 59 ° C.) 52.5% by mass
・ Magnetite (trade name: MTH009F, manufactured by Toda Kogyo Co., Ltd.) ・ ・ ・ 45% by mass
・ Polyethylene wax: 1.5% by mass
(Product name: Polywax 2000, manufactured by Toyo Petrolite)
・ Negative charge control agent (Fe-containing azo dye) ・ ・ ・ 1.0% by mass
(Product name: T-77, manufactured by Hodogaya Chemical Co., Ltd.)

The above composition was powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder at a preset temperature of 150 ° C. to obtain a kneaded product (3). After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a volume average particle diameter D _50v of 7.3 μm.
Further, the pulverized product was classified and spheronized using a Nobilta manufactured by Hosokawa Micron Co., Ltd., and a toner having D _50v : 7.8 μm, D _84v / D _50v : 1.25, and D _50p / D _16p : 1.29. Mother particles (1) were obtained. The average toner shape factor of this toner was 130.

(Preparation of external additive toner (1))
-Base toner particles (1) ······ 100 parts by weight · Silica oil-treated silica ···· 1.5 parts by weight (Primary particle size 7 nm, trade name RY300, manufactured by Nippon Aerosil Co., Ltd.) )
・ HMDS-treated silica: 2.3 parts by weight (primary particle size: 40 nm, trade name: H05TM, manufactured by Wacker Chemie)

The above composition was mixed with a Henschel mixer to obtain an externally added toner (1). Silicone oil-treated silica was added after HMDS-treated silica was added.
The total amount of energy of the obtained externally added toner ((1)) was measured using a powder rheometer FT4 (manufactured by freeman technology) by the method described above.

[Examples 2-6 and Comparative Examples 1-2]
In the preparation of the externally added toner (1) of Example 1, the externally added toners (2) to (2) to (2) to (2) are similarly obtained except that the amounts of the base toner and the silica added as the external additive are changed as shown in Table 1. 6) and comparative external toners (1) to (2) were prepared. Table 1 shows the total energy amounts of the obtained externally added toners (2) to (6) and comparative externally added toners (1) to (2).

[Comparative Example 3]
The toner of Example 1 of JP-A-11-143115 was produced by the method described in the publication to obtain a comparative external additive toner (3). Table 1 shows the total energy amount of the comparative external additive toner (3) obtained.

[Example 7]
(Preparation of external additive toner (7))
-Base toner particles (3) ... 100 parts by weight-Silica oil-treated silica ... 1.1 parts by weight (Primary particle size: 12 nm, trade name: RY200, Nippon Aerosil) (Made by company)
HMDS-treated silica: 1.8 parts by weight (primary particle size: 40 nm, trade name: H05TM, manufactured by Wacker Chemie)
The above composition was mixed with a Henschel mixer to obtain an externally added toner (7). Silicone oil-treated silica was added after HMDS-treated silica was added.
The total amount of energy of the externally added toner (7) obtained was measured using a powder rheometer FT4 (manufactured by freeman technology) by the method described above.

[Examples 8 to 9, Comparative Examples 4 to 5]
In the production of the external additive toner (7) of Example 7, the external toners (8) to (8) to (8) to ( 9) and comparative external additive toners (4) to (5) were prepared. Table 1 shows the total energy amounts of the obtained externally added toners (8) to (9) and comparative externally added toners (4) to (5).

<Evaluation>
Fuji Xerox Printing Systems modified so that the rotation speed Va of the stirring member and the rotation speed Vs of the developer carrying member can be independently controlled using the obtained externally added toners of Examples 1 to 9 and Comparative Examples 1 to 5. The following tests were performed using DocuPrint 305 manufactured by the company under the following conditions.
・ Rotation speed of stirring member: 30 rpm
・ Rotation speed of developer carrier: 150 rpm

(Measurement of initial image density)
In a 30 ° C./80% RH environment, a solid image of 3 cm × 3 cm was printed, and the image density of the obtained image portion was measured with a reflection densitometer X-rite 404 manufactured by X-rite.

(Evaluation of changes in image density after high image density continuous output)
In a 30 ° C./80% RH environment, 200 images having an image density of 50% are continuously printed, and the image after the 200th image is a solid portion of the image obtained by printing the image used for measuring the initial image density. The image density was measured with a reflection densitometer X-rite 404 manufactured by X-rite. The absolute value (ΔD) of the difference between the obtained image density and the initial image density was calculated and evaluated according to the following criteria.

◎: ΔD is less than 0.05 ○: ΔD is 0.05 or more and less than 0.10 Δ: ΔD is 0.10 or more and less than 0.20 x: ΔD is 0.20 or more

(Exposure of developer from developing device)
The inside of the apparatus was visually confirmed after printing 10,000 sheets to see if the developer was ejected from the developing apparatus.
○: No ejection △: Slight ejection, but no practical problem ×: ejection

  As shown in Table 1, in the case of a magnetic one-component developer having a total energy amount of 10 to 100 mJ in measurement with a powder rheometer under the above conditions, image density corresponding to output at various image densities is shown. Reduction was suppressed and high-quality images were output stably. When the total energy amount is less than 10 mJ, the image forming apparatus is contaminated by the ejection from the developing device.

  In the case of a combination of the rotation speed of the stirring member: 7.5 rpm and the rotation speed of the developer carrier: 150 rpm (Va / Vs = 0.05), or the rotation speed of the stirring member: 160 rpm, the developer support Even in the case of the combination with the number of rotations of the body: 80 rpm (Va / Vs = 2.0), when the toners of Examples 1 to 9 are used, the change in the image density after the continuous output of the high image density is observed. There was little jetting from the developing device.

It is a schematic block diagram which shows an example of the image development apparatus used for the image development method of this invention. It is a figure for demonstrating the measuring method of the total energy amount with a powder rheometer. It is a figure which shows the relationship between the vertical load and energy gradient which were obtained with the powder rheometer. It is a figure for demonstrating the shape of the rotary blade used with a powder rheometer. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus used in an image forming method of the present invention.

Explanation of symbols

10 Developing means (developing device)
12 Electrostatic latent image carrier (photosensitive drum)
20 Developer carrier (developing roll)
26 Stirring member 40 Charging means 42 Latent image forming means 44 Transfer means 46 Fixing means

Claims (5)

  Magnetic single-component development characterized by a total energy amount of 10 mJ to 100 mJ when measured with a powder rheometer at a tip speed of the rotor blade of 100 mm / sec, an entrance angle of the rotor blade of -5 °, and an air flow rate of 20 ml / min. Agent. Including toner base particles containing at least a binder resin and magnetic powder, and an external additive externally added to the toner base particles,
The external additive includes at least inorganic fine particles having a small particle diameter of 5 to 20 nm and inorganic fine particles having a large particle diameter of 30 to 80 nm. Magnetic one-component developer.   3. The magnetic one-component developer according to claim 1, wherein the inorganic fine particles having a large particle diameter are prepared by externally adding the inorganic fine particles having a small particle diameter before the inorganic fine particles having a small particle diameter. The developer accommodated in the developer accommodating portion is agitated by an agitating member, a developer layer is formed on the developer bearing member, and an electrostatic field is applied via the developer layer by applying an electric field. A development method for developing a latent image on a body,
The ratio Va / Vs between the rotation speed Va of the stirring member and the rotation speed Vs of the developer carrying member is 0.05 to 2.
The developing method according to claim 1, wherein the developer is the magnetic one-component developer according to claim 1. A charging step for charging the electrostatic latent image carrier, a latent image forming step for forming an electrostatic latent image on the surface of the charged electrostatic latent image carrier, and developing the electrostatic latent image with a developer containing toner. A developing process for forming a toner image on the electrostatic latent image carrier, a transfer process for transferring the toner image onto a transfer material to form an unfixed transfer image, and the undetermined image transferred on the transfer material. A fixing step of fixing a transfer image of the wearing, and an image recording method comprising:
An image forming method using the developing method according to claim 4 in the developing step.

Images